LTBR"äRY

RECEIVED

SEP 41963

an Tç^VlLLE BRANCH,

GRADE

DEFECTS IN

HARDWOOD

TIMBER

AND LOGS

AGRICULTURE

HANDBOOK NO. 244

U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICE
GRADE DEFECTS IN

HARDWOOD TIMBER AND LOGS

By C. R. Lockard, forest products technologist; J. A. Putnam, hardwood specialist; and

R, D. Carpenter, forest products technologist.

Agriculture Handbook No. 244 August 1963

U.S. Department of Agriculture Forest Service

(Supersedes AH 4, Log Defects in Southern Hardwoods, June 1950)
CONTENTS

Introduction _. .

Page

1

Factors afl'ecting qi

Abnormalities and

Relation oí log

Classes of log :

Log' surface abnorn

lalit}'.

i'rade t

grade

bnorir

alities

lefects

defects to

alities

use._.

1

•>

O

O

*)

5

Bulge ,)

Bumps

Burls

--- - -

(j

Butt scar 7

Butt swell___ S

Canker _ . 9

Conk 9

Epicormic branches

bud clusters

Flanops

\nd adven titious

in

1(1

Flutes _ . 11

Fork 11

Gum lesions. _ 11

Large lióles \'>

Medium holes _

Small holes- -.

12

10

Log knots _ _. 15

Limbs 17

Overgrowths 17

Seams 'M

Split.. _ _ 24

Surface rise 2.5

Wounds_ 25

Log end abnonnalities

Double pit 1]

Grease spots

Grub channels

(lum spots

Loose heart

Alineral streak and slain

Pin worm holes

Ring shake._ _ __

Rotl ^"

Shot worm holes

Soak

Spidei' heart

Spot or Hag worm lióles _.

Wind shake

Evaluation of timber and logs

Log classes and log gi'inhs.

Defect evaluation in gj-admg

Log graihng systems

General appearances that warn of log

defects.

Signs in standing timber

Signs on end of log

Indications of deterioration in dead timber

or stored logs

Appendix

Basic specifications for standard hardwood lumber grades.

Common and scientific names of species mentioned

ni

Page

2«

27

27

27

28

28

28

29

29

M)

A2

:]4

34

34

34

35

35

36

37

38

38

38
Introduction

The appraisal of hardwood timber and <ïradiii«iof hardwood logs were for a long time held to be

a mysterious art, with most of the deep secrets

shared only by oldtime timbermen. Even they

were not infallible, however; when moving to a

new locality, many suffered financial revei-ses

through failure to judge timber quality accurately. Consequently, the idea developed that

there are invisible basic features in hardwood timber of the same species found in widely separated

tracts, and that without highly localized experience a good appraisal is no more than a lucky

guess. The truth is that although these regional

variations exist, quality determinants can be isolated, evaluated qualitatively, and systematically

described for universal application to both

standing timber and logs.

The need for complete undei-standing of all

factors affecting hardwood timber quality is great.

Many appraisal problems formerly unimportant

because of low stumpage values for generally

high-quality timber have recently become pressing

and fonnidable. The reality here is the acknowledged widespread decrease in average level and

increase in variability of hardwood timl^er quality. Perfect trees are rare; poor trees have become abundant. Volume per acre is lower and

the trees are smaller than in the past. Tree size

is markedly important because the factors that

reduce quality take a greater toll in small timber

than in large timber. For example, the same

number of overgrown log knots is obviously less

damaging when scattered through a log averaging

3 to 4 per thousand board feet than when contained in logs averaging from 6 to 10 per thousand

board feet.

Loggers especially are in dire need of a basic

understanding of hardwood timber quality. Log

making in liigli-])rired timber of variable quality

which fails to allow for and treat intelligently

those factors affecting quality often results m material losses. The determination of the lower limit

of log or tree niercliantability becomes one of the

most vital i)oints. Merchantability of hardwood

timber can no longer be judged simply on size,

straightness, superficial smoothness, and freedom

from rot and shake. It is known to be equally intluenced by type, location, and concentration of

log defects, including many which are so

inconspicuoiis as to be lilmost unnoticeable.

To utilize presently high-priced stumpage most

profitably, it is increasingly necessary to prepare

the har\est from a given hardwood stand for

several markets rather than for only a single use.

This means that the logging operation might produce veneer logs, factory lumber logs, logs for

structural items, logs for low-grade construction

lumber, stave bolts, dimension bolts, fence posts,

pulpwood, charcoal or chemical wood, and fuelwood. An understanding of hardwood timber

quality is essential for such multiproduct logging

operations.

Another important need for definition of hardwood timber quality arises from the current

widespread application of scientific forest management. A forester, marking timber under a

program designed not only to feed the proper raw

material to individual plants but also to maintain

and improve the forest growing stock, must have

a veiy thorough knowledge of the factors which

govern quality.

This pul^lication is especially intended to describe the least understood determinants of log

quality: those indicators, on the surfaces or ends

of the" logs, of quality-degrading blemishes in the

interior.

Factors Affecting Quality

To isolate and examine the basic determinants

of the quality of a log and thus of a tree, it is

necessary to set up a standard. A theoretical

standard would be a straight, cylindrical tree

trunk consisting entirely of absolutely perfect

wood. Such a phenomenon is never found in

nature, if only because every tree has taper and

'I pith center.

A more practical standard for quality comparison is a log with the following specifications :

, ! It is a butt log, round or only slightly oval

111 cross section.

2. It is 16 feet long and about 24 inches or more

in ciiameter atthetop end.

;5. It is straight, but with slight taper and butt

flare. . , _,,

4. The wood is straight grained. There is no

requirement as to other characteristics of the

wood, i.e., whether heart or sap, uniform or

variable in density or color.

.5. The log has a "heart center" within a central

cylinder of "Ciiameter not more than 40 percent of

the loo- diameter. This heart center contains limb

stubs "and pith center only; it is free from rot,

shake, stain, and similar imperfections.
U.S. DEPAKTMKNÏ OF AGRICULTURE HANDBO301Í!

6. Between the heiui center and llie sliih ¡s ii

qnulity zone in wliich (here ¡ire no iiiipoi'lVcl ions

such as knots, hoU's, liai'k porlu'ls, mineral slain,

or rot.

Standard producís ol" higli value will l)e ciil

from such a lo<>'. Any deviation from I hese specifications, except for a modérale one in size, will

reduce average value of i)otential producís. The

deviations thai are most im¡)orlaiit, occur mosi

frequently, and—for all })raclical purposes—determine quality are (1) change in posilion of log

in tree, (2) reduction in size of log, (.''>) crookedness, and (4) imperfections in eilhei" tlie heart

center lexce])t for kmils and pith) or in the outer

rim of wood.

Position affects quality because the fartlier u])

the tree the log is, the larger the lu-art center, and

the coarser the limb stul)S in it are likely to be.

Change in fiise, especially in dianu^ter, is very

important. A decrease in diameter will cause a

rapid increase in the [)ropoi'tion of products containing the coarse heart-center blemishes. If

made into standard factory lumber, the logs of the

larger diameters will yield wider and more valuable lioards: and the widei' the boards, the greater

the i)ossibility of raising values by primary ripping to eliminate or segregate blemishes. Similarly, large timbers, which obviously can be cut

oidy from large logs, are more valuable ¡¡er unit

than smaller ones. Changes in lengtli are not so

inu.)ortant in the indi\idual log, for the highest

grade of hmilier iiei'mits pieces of all lengtlis down

to 8 feet. Nevertheless, there ai'e definite limitations on the iiercentages of short lengths that can

be included in large shipments of a given grade,

and there is sometimes a ))remiuni on shipments

containing all long lengths (U feet and K) feet).

For logs of a given position and size, rroolednes.s is an important cause of reduced product

value. There are two valuations of this. One is

vreep. a gradual curvature from a straight line

drawn from one end (d" the log to the other. The

other is a sharp deviation within the log, called

rrool'. The innuediate effect of either is to l)ring

the low-grade center nearer the surface when tlie

log is sawed. Sweep and crook are sometimes

caused by a broken fork or heavy limb and, tluis,

may be related to abnormally coarse pi'oduct cliaractenstics. The effect of crookedness on quality is

complex, but in all kinds of logs it reduces "the

va ue of the product by causing an abnormal distnbution of core defects. Besides reducing the

value, sweep and crook inevitably reduce the recoverable volume of the product They also increase production costs, for crooked logs are hard

to nandle on rolhvays, are difficult to fit into loads,

and frequently reduce the rate of sawing.

Fuia] common deviations take the form of imperfecUons in the slah zone, quality zone, or the

lu'di't center. Such imperfections are broadly

called defects. Of all the factors affecting wood

([uality, they are unquestionably the most important. 'J'hey fall into two main categories: (1)

Those which reduce the volume of sound wood or

lower its durability, and (2) those which lower its

strength or otherwise limit its utility. The first

(;ategory comprises tlie so-called seahible defects

(chiefly rot, shake, and checks), and their productloss effect is allowed for in scaling. The second

comprises the gi'tide defeetn—e.g., knots, stains,

holes, and bark pockets, which are generally not

removed in primary manufacture. Grade defects

control the quality of the part of the log expected

to yield uiddemished wood, and are basic determinants of strength, durability, or fine appearance.

The term "defective timber" popularly connotes

rotten or ovennatui-e trees, even though these may

contain much usable material. The amount of

scalable defect, together with size limitation, is

often the main criterion limiting merchantability

of logs or trees in commercial practice. Actually,

timbei' from which unusable nniterial (scalable defect) will be removed in manufacture is not necessarily defective; there may be no serious blemishes (grade defects) in the remaining usable

wood.

On the other hand, perfectly sound trees (without scalable defect) may be worthless because of

the prevalence of grade defects which cannot be

eliminated in manufacture. Since a defect that

reduces volume (e.g., rot) is entirely different

from a defect that reduces utility (e.g., knot), the

terms "scalable defect"' and "grade defect" are

good ones to express this difference. The latter

should be applied only to those imperfections that

lower the quality of the product into which sound

wood in the tree or log will be converted.^ It is

from this viewpoint that grade defects are

discussed herein.

T^sage gives the term "grade defect" to abnornuilities or irregidarities on the log surface as well

as to imperfections in the wood. These outside

features are really indicators of imperfections in

the underlying wood and could be termed "grade

defect indicators." For example, a branch stub is

an indicator of a knot in the product to be sawed

from the log. Nevertheless, because timber appraisers deal with logs or tree stems as such, and

not as sawn products, this publication designates

these surface features as log grade defects or degraders. On the other hand, imperfections in the

wood are designated as prodnct grade defects.

" This distinction is not always clear cut ; scalable defects, when affecting only small areas may he left in the

product, where they impair strength or utility and thus

become grade defects.
GRADE DEF^TS IN ÜAKUWUUU TíMBJDK AJNU LOGS

Abnormalities and Grade Defects

Whetlier a log surface or end abnormality is a

log grade defect, and whether the indicated blemish in the wood is a product grade defect, are determined by the specifications for the proiluct into

which the log is to manufactured. Thus, log and

product grade defects can be defined and evaluated only in relation to product requirements.

For example, mineral streaks ^vould ruin the

utility of maple lumber for fine clear finish tabletops and, thus, would be considered product gi-ade

defects. They would not, however, affect the

strength of a piece to be used as a tie, and for this

use would not be regarded as degraders. An unsound knot, say 234 inches in diameter, in the middle of a floor joist -2 inches by S inches by 16 feet

v.ovild render the piece useless for the intended

purpose and, therefore, would be a serious product grade defect. The same knot in an otherwise

clear 16-foot board from which it was desired to

cut two 7-foot clear pieces for bedrails would be

a dégrader only if it prevented the cutting out of

the required clear pieces. Its degrading effect

would be equaled by a somid 14-inch knot that

would pass unnoticed in a floor joist. For the

bedrail use the piece would actually be of the

highest recognized grade.

RELATION OF LOG GRADE

DEFECTS TO USE

Thus, in examining the various degraders and

other factors that determine the quality of a

hiU'dwood log, the nature and expected use of the

end products must be given prime consideration.

Each use has its own technical requirements,

which are reflected in varying tolerances for type,

number, and distribution of imperfections permitted in the product. Over the years the sawmill trade has found that hardwood products

can be grouped according to basic use into one of

three broad classes. These are (1) standard factory lumber, (2) construction lumber, and (3)

miscellaneous low-grade or local-use products.

In this handbook the terms factory log, construction log, and local-use log refer to logs suitable

for the production of items falling into one of

these classes.

At first, this handbook may appear to give too

much attention to sawmill products and not

enough to veneer, cooperage, dimension and hanflle stock, or other specialities. Although these

may assume considerable local importance, they

are minor in the total utilization of hardwoods.

Irobably 80 percent of commercial hardwood

sawtimber is cut into products for the three gen-

«id uses described. Furthermore, the specifications for specialty products are closely related to

tiose for factory lumber in that relatively .short.

Clear pieces of almost perfect wood or" veneer

sheets witli few defects are desired. It is probable that studies in any locality will show that

the significance of grade defects of specialty

])r(Mluc(s can l)e judged on about the same basis

as t hose for factory lumber.

Fdctoi'y uxe is based upon producing lumber

that is to be reçut into i)ieces free or relatively

fi-ee from blemishes and imperfections. Figure 1

shows a log suitable for production of factoryclass lumber. The grade of sucli lumber is determined by specifications of the standard grading

rules of the National Hardwood Lumber Association.- Application of these specifications controls the yield of high-quality pieces that can

l)e cut from any board of a given grade. The

technical base for the grading is the clear-face

and sound cutting. High-grade boards are those

which will yield high percentages of clear-face

cuttings, with individual cuttings relatively large.

Low-grade boards are those which yield low percentages of clear-face or sound cuttings, generally

only in the smaller sizes. Tabular statements of

basic specifications for factory lumber are found

in the appendix, page ?>8.

Construction use is that in which the pieces are

to be used intact for structural or weight-bearing

purposes. A log suitable for producing this class

of lumber is shown in figure 2. Specifications for

construction lumber are contained in the National

Hardwood Lumber Association's 1943 "Standard

Specifications for Structural Stress Grades of

Hardwoods and Cypress," in the tie specifications

of the American "Eailway Engineering AssociFiGURE I ^Factory lumher class log. This type of log is

relatively straight and will permit much center defect.

Blemishes pre.sent in outer rim (quality zone), however,

must be so spaced that certain minimum amounts 01

l.lemish-frec cuttings can be obtained. Distribution,

i-fither than size and character of log grade defects, is

the mcjst iuu)ortant quality factor.

'Rules for the measurement and inspection of hard-

^^ ood lumber, cypress veneers and thin lumber. National

Hardwood Lumber Association, Chicago, 111. Jan. 1962.
U.S. DEPARTMENT OF AGRICULTURE HANDBOOK iVU. 1^44

at ion and in the staiulard specifications of the

American Society for Testino- and Materials for

structural wood joists and plaidvs, beams and

stringers, and posts and timbers. Tlie.se specifications'^ in general control strength. Additional

products iu this class are conMnictioii- and vtiïlty

hoards as defined in the current rules of the National Hardwood Lumber Association.-

III construction use, knots and other blemishes

are limited to sizes that will keep impairment, of

piece strength within satisfactory limits, causing

log requirements to differ from those for factory

lumber use. Construction use specifications are

rigid on this point, compared with factory lumber

use tliat allows for progressively more product,

degraders from high to low grades. In factoiy

use, for e.xample, enougli boards can often be cut

from the outside of a log that has a rotten, shaky

interior and large but widely spaced individual

.surface abnormalities to obtain a high average

quality of product. Such a log might be worthless

as a source of construction material.

MificeVaneovs or local vse is that not generally

covered by any standard specifications (fig. 3

shows a good local use log). High strength, great

durability, clear yields, or possibility of use intact

is not required. The products are of low value and

are mostly .sold in local or restricted markets for

such purposes as material for secondary farm

buildings, crating, pallet stock, mine ties, industrial blocking, and miscellaneous construction.

Whereas the products for the first two classes are

usually sold over a wide area on generally accepted specifications through a variety of marketing channels, local-use materials are generally sold

direct to the user hy the producing mill on basis of

mutual understanding as to .specifications.

Any system of log classification represents a sort

of one-way street. That is, all loffs are allocated

to the highest cla.ss to which they are naturally

adapted, regardless of any suitabiíity for the purposes of a lower class. This high use may be for

factory lumber or for construction lumljer, deFrr T •> F-455e26

fw'ts ,^a„ |,e 't:''^ and „iternally sound. Grade de-

«attere nnrin'"' '^ "^^y ^""e »ot, bunched but are "erecl and small. Products are judged on strength.

F-45562T

FIGURE .3.—Local- or miscellaneous-use class log. This

type of log, because of .size, pLacement, and character of

degraders, scalable defects, or crookedness, will yield

only small percentages of defect-free wood from the

quality zone or of standard construction materiaJ. It

will yield a variety of low-quality items for which

strength or appearance is not important. The evident

"bump" indicates a high proportion of scalable defect.

pending upon local situations. The lowest class as

shown by average sale value is usually local-use.

Strictly speaking, no log suitable for local use is

also suitable for construction use. Neither can

logs suitable for construction material be economically manufactured into factory lumber. On the

other hand, higher class logs often are used for

production of lower-class products. It is common

to observe logs best adapted to factory lumber being cut into ties and, vice versa, to see mills producing standard lumber from logs best suited for

timbers. At both tie and lumber mills can be

found logs unsuited for either type of production.

The reasons for this are (juite complicated. One

reason is that operators lack knowledge of available research-based log class specifications that can

guide them in allocating these three tyi^es of logs

to the most appropriate use.

So far this discussion has dealt with log use

classes. The next step is to evaluate wood blemishes in relation to each log use class. In factory

lumber logs the most important wood blemishes

are those in the outer rim of wood (quality zone).'

Few, if any, of the surface indicators of blemishes

located in this zone can be disregarded; most are

degraders. This is true regardless of the size or

soundness of the abnonnality and the underlying

l)lemish. In construction logs the reverse may be

true. In one construction log, size of dégrader

may be the controlling factor; in another, the

critical degraders may be only those unsomid ones

in the heart center. In local-use logs the lowgrade nature and unexacting waste tolerances of

the products make log quality requirements unexacting. In these logs the main consideration is

' Defined generally as the area under the slab zone

and outside a heart center, which is itself defined as a

central core with a diameter 40 percent of average log

diameter (inside bark) at point of measurement.
'IIW!ÍB^Í''©ííFECTS E IN HARDWOOD TIMBER AND LOGS

excessive size of log defects or excessive amounts

of scalable defects which arbitrarily disqualify the

log for the class.

CLASSES OF LOG ABNORMALITIES

Log abnormalities can be divided into two general classes : those found on the surface of tlie log,

and those found on the ends. Bej'ond this there

can be no general classification. One reason is

that, although most of the important blemishes in

wood are associated with abnormal features visible

on the log surface or end, some visible irregularities do not reflect imperfections in the wood. Another reason has already been discussed : whether

or not the blemish is a product defect depends

upon the class of log in which it is found, for its

effect depends upon the specifications of the product to be made from the log.

It will be shown that certain abnormalities indicating wood blemishes may be disregarded as log

grade defects in any type of log under certain conditions, and that some may never be disregarded.

Certain kinds of abnormalities that may have been

included in the logs through operational error can

sometimes be disregarded.^ When evaluating

quality in standing timber, an abnormality may

be disregarded if it will not be included in the logs

that are to be cut out. Also, size and character of

the abnormality are important conditions, particularly in construction logs. Concentration, too,

is important in judging significance, particularly

of end degraders and especially in factorj' logs.

Position of dégrader within tlie log is another consideration, depending on log use class. In factory

logs the eliect of product defects and imperfections confined to the heart center is minimum; in

consti'uction logs it is maximum, particularly in

small and medium diameters. In local-use logs

there are fewer degrading or disqualifying defects

than in other classes. Tlie important items here

are unsound scalable defects which are taken into

account only in the aggregate to determine net

scale and wliich, if excessive, disqualify the log.

Other types of abnormalities are often superficial. This means that they are in the slab zone,

they extend into the log for a distance less than

one-tenth of the log diameter, and do not enter the

milling frustum or an inscribed square timber

deeply. In such cases they can be disregarded.

Since the conditions which make a surface abnormality a log grade defect in one case and not

in another vary so much, there can be no general

classification covering all abnormalities and all log

types. Tlierefore, the following discussions of individual log abnormalities cover not only the

description of the abnormalities but also their significance as degraders judged in relation to use

classes or other variables. No mention is made of

the degree of degradation caused by log and wood

abnormalities classed as defects. . Within a given

class of log some defects are more damaging than

others, but tlie effect may be conditioned by such

other factors as log diameter and straightness, or

position relative to other log grade defects. The

degree of effect is discussed under the heading

"Evaluation of Timber and Logs," p. 34.

Log Surface Abnormalities

Log surface abnormalities are unquestionably

more important than end abnormalities. There is

a better chance of observing indicators of wood

blemishes on the surface than of seeing the blemishes themselves on the log end. Moreover, the

distribution and frequency of product grade defects can be judged best from the surface indicators. All of the following discussions of surface

indicators of log grade defects are complete and

inclusive; an overgrown product blemish associated with a log surface defect is not di.scussed

again as a log grade end defect.

BULGE

Définition.—A bulge is a general enlargement

of the stem of a tree or log, in the nature of a

'In judging logs in standing timber the appraiser has

a certain latitude concerning the inclusion of grade defects. He can assume that cutters will use reasonable

judgment and eliminate a rotten section, bad crook, or

fork. When the log has been cut, however, it must be

judged "as is." The authors have foUowed this principle

m their judgments on log grade defects, except in the case

of features which are obviously included through operational error and the actual elimination of which is still

677366 o—62 2

"barreling" effect, often without an obvious cause

such as knot or callus formation. It may be near

a wound, rotten knot, knothole, or other point of

entry for rot. It generally indicates a cull section

with the extent of the rot shown by the extreme

limits of the deformation. There are two types of

btilges, butt bulge and stem bulge (figs, -i and 5).

Butt bulge is nearly always accompanied by

hollow butt. Rot generally extends beyond the

hollow, and the upper tapered-off limit of the

bulge usually indicates the approximate upper

limit of serious rot. Butt bulge has no special

relation to species, although it is most frequently

conspicuous in tlie oaks.= In species like sweetgum, elms, and ashes, even consideral)le butt rot

may not cause a clearly defined butt bulge. In

practical. It may be argued that any dégrader that can

be removed from the log or product without undue chopping of cutting could be disregarded, provided a loss in

scale were taken. Although there is merit to this argument, the nature of log grade defects cannot be adequately

discussed unless it is understood that they will not normally be removed from the log or product.

=^ A list of common and scientific names of species

mentioned is provided iu tlie appendix, p. 88.
U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

FIGURE 4.—Butt bulge.

these species the bark over even a slight bulge

often becomes smoother and darker and scales oiï

faster than in a sound stem. This is especially

true in sweetgum.

Stem bulge is not as common as butt bulge, but

may be found in any species.

Sig7iificance.—As indicated above, bulges are

evidence of internal rot and under good operating

practice are not included in logs. Butt bulges can

generally be so treated. If a stem bulge occurs in

the middle of a log, where it cannot be cut out,

then that section involved must be scaled out and

thus is a dégrader in factory hmiber logs. A

stem bulge will disqualify a log otherwise suited

tor Gonstruction material. In local-use logs the

bulges can be overlooked, provided the accompanymg rot does not exceed the scaling deduction

hmits set for the class. The identification and

evaluation of bulges is most important in dealing

with standing timber.

BUMPS

Definition.—A. bump is a protuberance on the

og which IS overgrown with bark (fig. 6). It

may be abrupt or it may be a smooth undulation

Which gradually tapers back in all directions to

FiGUEE 5.—^Stem bulge.

the normal contour of the log. A minimum bump

is arbitrarily defined as a swell on the surface with

a taper steeper than 1 to 6, i.e., it is a bump if the

distance from the center to the edge is less than

six times the height from the normal contour to

the top. If it has a taper flatter than 1 to 6, it is

cl assed as a surface rise ( p. 25 ). Low bumps have

tapers from 1 to 6 to 1 to 3 ; high bumps have a

taper sharper than 1 to 3. Abrupt bumps taper

less than 1 to 11/2.

Occurrence.—Bnuvps are likely to occur on aiiy

species. Low bumps are particularly noticeable

in hard and soft, maple, túpelo, soft elm, birch, and

the ashes, magnolias, and white oaks. High

bumps are conspicuously frequent in cedar elm

and white oaks on poor sites.

Sigyiißcance.—About nine-tenths of all bumps

indicate projecting sound or rotten limb stubs, a

cluster of adventitious buds, or an excessive folding or ingrowing of the bark over a scar.

In factory logs low bumps can be disregarded

in soft maple, túpelo, soft elm, birch, and the

ashes, magnolias, and more valuable white oaks;

but high bumps in these species are degraders. In

other species all bumps are degraders, for even

low ones cover blemishes that are usually in tne

quality zone where they limit clear cuttings.
BW7\L/I:J TrIKFECTS IN HARDWOOD TIMBER AND LOGS

FIGURE 6.—Bump.

In construction logs the effect will depend upon

the size of the underlying blemish. If the diameter of a high bump is less than one-third of

the diameter of the log at the point where the

bump occurs, or if the diameter of the feature underlying the bump is estimated to be less than

one-fourth of the width of a face of the largest

included timber (judged from the small end of

the log), then the abnormality can be disregarded

as a grading defect. If the underlying feature is

larger, it is a dégrader. In the case of a low bump

it is difficult to estimate the size of the underlying

blemish. Generally, however, the blemish will be

so large that a low bump must be considered a log

grade defect in overcup, chestnut, pin, scarlet, and

black oak, and in the water oaks and cedar elm.

In construction logs of other species low bumps

can be disregarded.

In local-use logs bumbs of both kinds are degraders if their diameter exceeds one-half of the

diameter of the log at point of occurrence ; otherwise they can be disregarded.

BURLS

Definition.—A burl is a sound, hard, woody protuberance on the bole, more or less rounded or

horizontally ridged in form, with no protruding

limbs, twigs, stubs, or indications thereof (fig. 7).

¿t is sometimes related to aborted adventitious

buds.

FIGURE 7.—^Burl.

Occurrence.—Burls, while uncommon, are most

often found on hard maple, cow oak, walnut, the

magnolias, and occasionally yellow-poplar, northern red oak, and yellow birch.

¡Significance.—A true burl is a surface indication that the grain in the wood is distorted into a

wavy, curly, or bird's-eye effect. Other similar

apparently sound abnormalities such as incipient

cankers, popularly classed as burls, may contain

considerable amounts of bark, rot, twig knots, and

even insect channels. In factory logs the true

burl, if it can be identified, technically is not a

dégrader. Nevertheless, because of the difficulty

of identifying true burls, all features popularly

considered as burls are classed as grading defects

in factory lumber logs. Since burls would unquestionably weaken construction material, they

must be considered degraders in these logs. In

local-use logs, however, they can be disregarded

unless they extend half way across the circumference of" the log at point of occurrence.

BUTT SCAR

Defnition.—K butt scar is a generally triangular or wigwam-shaped opening at the base of the

bole, from a few inches to several feet high (fig.

8). 'it may show weathered or stained sapwood,

rotten heartwood, or may be the opening into a

rotten hollow butt. When associated with advanced rot or hollow, it may be accompanied by a
8

U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

butt biiloe (]). 5). It. is ciuised by unytliino- that

"skins" the base of the tree. Fire is tlie most

common cause; other causes are loo-g-in<i and

cattle. Pill- :IIKI sliol-woriii daiiiaiie (|)|). 2!) and

;;i), wliicli are defects in factory lofi's, are

closely associated with butt scars.

Occurrence.—Butt scars may be found on all

species.

Signífímnce.—Since severe rot is generally

associated Avith butt scars, the log is usually

started above the butt swell. Sometimes, however, a butt scar of recent origin with a limited

amount of rotten or stained wood is left on the

log. In factory logs the area involved is a grading defeat even though scale deduction is made

for it. In conf<tructio7i loga a butt scar may be

disregarded if it and tlie associated rotten wood

are superficial and do not enter the included tie or

timber. In standing trees butt scar and associated

rot may be disregarded if the logs can be cut so

as to meet the minimum requirements of the log

class. Otherwise a butt scar is a dégrader. Butt

scar is not a dégrader in local-use logs.

BUTT SWELL |

Definition.—A butt swell is an enlargement of

the bottom end of the tree trunk, over and beyond

the normal stump flare generally found in all

species (tig. 9). It is a normal development, apparently related to wetness of site, but not to

injuries. Trees with butt swell are sometimes

called "churn-butted" or "bottle-butted."

In standing timber butt swell may be confused

with butt bulge. Butt swell is related to site

and confined to species list«d below. Butt bulge,

which is due to injury and internal rot, is found

in other species (especially oak) ancl is distributed

more widely. Sounding the butt with an ax or

carefully searching for wounds or butt scars will

aid in identification. In the log there will be no

question, for the wood in the butt swell will be

sound, whereas it is likely to be very rotten in a

butt bulge.

Occurrence.—Butt swell is found in túpelo,

swamp blackgum, red maple, and green ash.

Within the species the degree of butt swell varies i

FIGURE 8—Butt scar.

FIGURE 9.—Butt swell.

P—165679
f ^ aayjajiB^CTS £&:• IN HARDWOOD TIMBER AND LOGS 9

FIGURE 10.—Canker.

according to depth,

occurrence of water.

duration, and seasonal

Significance.—Butt swell is not a reflection of

and is not related to recognized imperfections in

the underlying wood. It does not lower lumber

grade and thus is not a log grade defect in factory

logs. Nevertheless, the wood in the swell is often

soft enough to limit the use to which the lumber

can be put. For instance, green ash lumber cut

from swelled butts, although graded by standard

rules, is classed in the trade as "cabinet ash" and

does not command the high price obtainable for

"firm or better" taken from farther up the same

tree. For construction and local-use logs the

túpelos are the only species to consider, and in

them the swelled section may be so soft as to be

worthless for any purpose at all. The species is

"^ally cut above the butt swell.

CANKER

Definition.—A canker is a definite, relatively

localized necrotic lesion, primarily of bark and

cambium (lig. 10). It is usually an entrance

for decay fungi and, wlicn conks are present, is

evidence of serious lioart rot.

Occurrence.—It is most common on the red and

water oaks, hickories, the ashes, and Ijlack cherry.

Siç/iiip'eiiiiee.—In good operating practice a

canker is nol inchided in the log. Should it be

included, it is a definite dégrader in a factory

log. It is a grading defect which will disqualify

a log otherwise suitable for construction material.

An included cankei' can in itself be disregarded

in a 1ocal-u.se log unless it contributes to scaling

deduction beyond the limit allowed for the class.

CONK

Definition.—A conk is a fibrous but sometimes

fieshy excrescence of definite form and structure

on the l)ole (fig. 11). It is the fruiting body of a

wood-rotting fungus contained in the tree.

Occurrence.—Conks may occur on all species.

Significance.—A conk generally indicates an

amount of rot, usually close to or in excess of the

perce.i:itage of gross log volume allowed in a merchantable log of any type. If the log ciualifies as

a factory Jog, the conk, together with the a'ssociated rotten area, becomes a grading defect. It

will limit cuttings outside of the heart center even

though scale deduction is made. In a log otherwise suitable for construction material conk is a

definite dégrader, for it is evidence of rot in the

log interior which will disqualify the log. In a

local-use log the conk can be disregarded, provided the rot with which it is associated does not

exceed the scaling deduction limit for the log

class.

F-465699

FIGURE 11.—Conk.
U s. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

F-455584

FIGURE 12.—Epicormic branch and adventitious bud

cluster.

EPICORMIC BRANCHES AND

ADVENTITIOUS BUD CLUSTERS

Definition.—Epicormic l)uds (fig. 12) are abnormal buds found at points on tbe stem unrelated

to the crown. They arise from latent or dormant

buds originatini«- in the leaf axil and thus may

persist within the cortical-cambial zcme indefinitely and can be activated at any time in response

to various stimuli.

Adventitious bud clusters, similar but independent in origin, may arise at any time during

the life of a tree. They often originate in the callus tissue resulting from wounding or bruising the

cambnuu layer, but may dexelop independent of

any such inerjiauical action. Very often they develop nito clusters of fine twigs of short life", and

ui thm case they are connuonly accompanied by

small bark pockets. They are not necessarily repi"-

titinus and are less conniion on most species than

fpicornuc branches.

(hTNrrnirr.--Th^y are found most frerpieutly

IJi 1 species of elm, oak, and maple, and on

eetiquu. ^

FIGURE 13.—Flanges.

scar are very small knots, small bark pockets, or

])Oth. The twig or branch stub that is apparent

on the surface may not extend very far into the

wf)od. However, a succession of others of similar

origin often appears dee])er -within the log. Wood

blemishes caused by either epicormic branch or

adventitious branches or bud clusters stop clear

cuttings and are log grade defects in factory logs.

The knots and bark pockets that the bud clusters

indicate do i\ot constitute degraders in construction logs and in local-use logs.^

FLANGES

Dt'fliiition.—Flanges are buttress- or wing-like

formations at the base of the tree (fig. 13). They

are exaggerated projections or convolutions of the

normal stump flare and usually extend up the bole

beyond normal stump height, sometimes for 4 or

.-) feet from the ground. They appear to be related to wetness and softness of ground.

ou

SW

'^'"''""'^'''""^•''-l^nderlying the epicormic branch

" Epicormic branches and adventitious bud clusters are

treated toRether because the blemishes and defects which

they reflect are very similar. Often they occur together,

witli the adventitious buds surrounding the epicormic

branch as shown in figure 12.
""" GKADë DEFECTS IN HARDWOOD TIMBER AND LOGS

Occurrence.—Flanges are common in elms,

water oaks, and soft maple.

Significance.~Th.& wood in flanges is, by definition, outside the milling frustum or included

timber. Furthermore, flanges have no relation to

blemishes or imperfections in the underlyingwood. Therefore, flanges are not log grade defects in any type of log.

FLUTES

Definition.—Flutes are folds or convolutions of

the surface of the trunk running up and down and

generally confined to the base (fig. 14), but occasionally extending up into tlie second log. They

generally include ingrown bark. Tliey appear to

be of normal origin, related to softness of site,

much as flanges are.

Occurrence.—They are commonly found in soft

and cedar elm, soft maple, and occasionally in

water oaks, pecan, and magnolias. The most exaggerated flutes are found in the elms.

Significance.—Flutes usually do not extend

deeply into the log at the small end. ^y]\e]] they

do not, they may be disregarded i}i all classes of

logs. In local-use logs they may be disregarded in

any case.

FORK

Definition.—A fork is a crotch between double

tops (fig. 15). It is sometimes included when logs

are bucked to arbitrary lengths.

11

Sig,nfi.carice.~~K hidden effect of a fork is double pith and, generally, a bark pocket. In the

tork portion grade outturn and volume yield are

both lowered significantly. Including a fork on

a log IS an oi)eratu)na] error, in construction logs

a scaling deduction for a section sliould be made

back to a i^omt beliind the separation. In factory

log.^ the seam and any enclosed bark should be

scaled out following the standard practice for deducting tor interior scaling defect ; but if the portion s(-ak.,l <»ut IS Ko large that it precludes cuttings then the fork is a log grading defect. In

standing timber, however, a fork is not a dégrader

It logs that fulfill the minimum requirements for

the log class can be cut. Forks can be disregarded

ni. local-use logs except for a scaling deduction.

GUM LESIONS

Defnltio».~Çh\\\\ lesions are groups of abnormal small wounds on the main stem that exude

gum. In black cherry they are the result of the

work ot at least two species of cambium mining

insects.' Tliey heal over each year, and new ones

appear m the same general area year after year.

In sweetgum a fungus {Botyryosphaeria rihis)

kills and dissolves strips of cambium tissue, and

black liquid storax oozes out of the bark fissures.

Healing resuhs in coarse vertical folds of in-

' A sum lesion which has a definite structure should

not be confused with "gumosis," a condition not evidenced

by such a characteristic.

FIGURE 14.—Flutes. FIGURE 15.—Fork.
U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

F-502323-24

FIGURE 16.—A. Healed bark lesion in sweetguni of the lower Coastal Plains showing prominent rib of abnormal wood

and folded bark projecting above .surface of log. The.se rilis become buried and hidden in large trees and result

in encased bark pockets—serious defects when the trees are cut into veneer and factory lumber. B, Older healed

bark lesions in Coastal sweetgum partially buried in the trunk. These indicate areas of abnormal wood, ingrown

bark and black-stained wood which seriously degrade veneer and factory lumber. Much more dense concentrations and/or coarser lesions wcasionally f)ccur which make short sections of bole unfit for construction logs and,

sometimes, even for pulpwood.

grown bark. "Gum spots" in sweetsjuni wood, in

contrast, are probably basically similar in origin

and nature to those in cherry, but much less frequent and less distinct. Also, they are -selflom

related to ¡ngroion lark.

Oreurrenre.—Cywm lesions are found most frequently on sweetpum at the souther)! extremity of

its range, and on black cherry. Ashes, persimmon, and túpelo gums are also occasionally

aflfected.

'S'/r/íii/icffíífí'.—Underlying the giunmy surface

are many small bark pockets and giun streaks in

the wood. Figure 16 shoAvs the distinctive nature

ot hark lesion of sweetgum. Wood blemishes

caused by all of these lesions stop clear cuttings

iUKl are grade defects m factory logs in sweetgum.

llie highest grades of black cherry lumber, however admit gum in the "clear face!" cuttings, and

the lumber is graded "sap and gum-no defect."

ineieiore, gum lesions are not degraders in black

n^eir.v factory lumber logs. They may be disre- garded

species. "' ^''nxfnirtion and loral-u.^e logs of both

LARGE HOLES

Definifio7i.~J

ings over -"irge holes are unoccluded openone-half inch in diameter (fig. 17).

Among their causes are rotten knots, woodpeckers'

removing insect larvae or excavating rotten spots,

and mechanical damage.

Orriirrence.—Large holes may be found in all

.species.

''Significance.—In factory logs all large holes are

log grade defects. In constimction logs they are

degraders if their size is over one-third the diameter of the log at the point of occurrence, or if,

regardless of size, they extend more than 3 inches

into the included timber. If they are smaller or

shallower than this, they may be disregarded, provided they are surrounded by sound wood. Otherwise, they are grading defects. In local-use logs

large holes may be disregarded unless their size is

over one-half the diameter of the log at the point

where the hole occurs.

MEDIUM HOLES

Defnilion.—Medium holes are unoccluded openings, %6 to 1/2 inch in diameter, through the bark

which may or may not continue into the wood.

They include entrance and emergence holes of

grubs, bark scarrer holes, tap and increment borer

holes, and openings made by sapsuckers.

It is not clifficult to determine the origin of the

holes. Grub holes are caused by roundheaded
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 13

F—465595

FiGtjBE 17.—Large hole.

borers and carpenter worms. The grub galleries

arecleancut and usually stained; they are always!

more than 1 inch deep in the wood, are irregularly spaced, and ramify upward through the

wood. If these holes have remained open, there

has been subsequent activity by other insects, usually carpenter ants. In such cases decay fungi

enter, and the ants excavate the rotten wood, increasing the size of the galleries to make their nest

cavities. Associated with these will be ingrown

bark and callus tissue (fig. 18).

Recent or fresh bark scarrer attacks appear as

open holes about one-fourth inch or less in diameter. They can be identified by their round, irregular outline and by their not entering the wood.

The work of bark scarrers and grubs results in

frothy exudation on the bark which turns a dirty

brown.

Increment borer holes are of the same general

character as grub holes but do not ramify. Sapsucker holes are usually found in rows or bands,

although occasionally the entire log may be

677366 O—63 3

freckled with them. The individual holes usually

extend slightly, if at all, into the wood.

Occurrence.—Medium holes are found on trees

of any species. Sapsucker work, which results in

the faniiliar bird peck, is most often found in the

hickories, elms, sweetgum, yellow-poplar, and

water oaks, ))ut occasionally in the other oaks, and

in maples and birch. Insect work is more prevalent in the oaks. Tap holes will be found only in

sugar ma])le butt logs.

F-502325-26

Figure 18 —Carpenter ant work within grub gallery : A,

Old carpenter worm scar on Nuttall oak with exit hole

kept open hy carpenter ants ; B, interior of Nuttall oak

under scar in A. Ants kept hole open for 30 years after

grub adult left tree. Arrow shows location of bark at

time of grub attack. Dark heartwood at right is rotted

and was being removed by ants for a nest cavity.
14 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

FIGURE 19.—Grub hole.

B'-465939

Significance.—Except for extreme concentrations of grub holes or associated carpenter ant

work, medium lióles can be disregarded in construction and local-use Jogs. In factory logs they

may be extremely important defects, but significance varies with origin, age, or concentration.

Grub holes (fio;. 19), increment borer holes, and

tap holes are definitely grading defects in factory

logs, for the hole or channel in the lumber limits

the length of cuttings. Carpenter ant work sometimes enlarges these openings and this increases

the degrading effect.

Both increment borer and tap holes are generally accompanied by severe stain. In addition,

tap holes so often contain forgotten dangerous

metal spouts that butts are usually "jumped"

when a metal detector is not used at the mill.

Bark scarrer holes (fig. 20), if definitely identifiable, may be disregarded in all three classes of

logs because the holes are inherently superficial,

and often actually not in the wood at all. Fresh

holes show exudations and stained bark. Caution

is necessary here because where holes are present

earlier attacks are vei-y likely to have occurred.

Further treatment will take place under the

discussion of insect-caused overgrowths.

Significance of sapsucker holes depends primarily upon age and concentration. Fresh or

light bird peck (fig. 21) may be disregarded in

all types of logs. Test for freshness is lack of

associated similar holes that are occluded (filled

with callus tissue) after injury to the cambium.

Measure of lightness is four pecks per square foot.

There are tw^o cautions in connection with light

and fresh bird peck. One is that trees so damaged

have generally been subject to previous and often

repeated attack, and in such cases will have

occluded holes ( Overgi-owths, p. 17). A second

caution relates to the hickories; here even light

bird peck often results in circular columns of

purple stain running for considerable distances

down the tree. This stain is not a defect on lumber, but does constitute a deg'rading influence on

handle stock. The degree of bird peck is not the

test for degradation. The test is occlusion.

Heavy bird peck (fig. 22) may be older and

usually is accompanied by occlusions. The effects

extencl into the wood in the form of bark flecks

or callus pockets. Thus, the chances are good that

in most species heavy bird peck is a log grade

FIGURE 20—Bari- s:^,

inner bark ^^a.s destroyed but no penetrati.;n of the wood occurred

F-502328-29

B, stained wood surface

( Scar is 1 by 11/2 inches.)
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 15

r^c

FIGURE 21.^Light bird peck.

defect in factory logs (fig. 23), but not in construction and local-use logs. In yellow-poplar,

however, especially on good sites, bird peck is

often not a dégrader even though occluded. A

test to determine this must be made locally.

SMALL HOLES

Definition.—Small holes are unoccluded openings less than three-sixteenths inch in diameter

leading into the wood (fig. 24). They are often

associated with rot or wounds and confined to the

immediate • vicinity thereof. They are made by

several genera of beetles, including ambrosia, and

larvae of the shot worm beetle.

Occurrence.—There appears to be no significant

relation to species. Ambrosia beetle damage occurs more often and is generally heavier in the

softer and "sappier" species such as sweetgum,

out is also found to a damaging degree in the

harder species. Shot worm holes are most prevalent in red oaks, ashes, and sweetgimi and,

generally, in the heartwood.

Significance.—Small holes on the surface are

often accompanied by other features, such as

^vounds or rot which may or may not be log grade

FIGURE 22.—Heavy bird peck.

defects. In factory Jogs the usual effect of small

holes is to increase the already defective area containing the wound or rot. Nevertheless, even if

not otherwise defective, the area in which the insects work is definitely a degraded area. Small

holes may be disregarded in construction logs and

in local-use logs.

LOG KNOTS

Definition.—Log knots are cut or brokeri-off

limbs or sprout branches, green or dead, protruding, flush, or depressed, but with exposed sound

or I'otten wood (figs. 25 and 26). If the exposed

wood is sound, the log knot is "sound"; if rotten,

it is "unsound."

Occurrence.—Log knots are common to all

species, but tlie frequency depends upon the habit

of the species. In eottonwood, túpelo, yellowpoplai', and the ashes and basswoods, for example, occurrence is conspicuously limited. Pin oak,

scarlet oak, and (on poor sites) black oak are

conspicuously knotty.

Significance.—A log knot on the surface of the

log or a branch on a tree represents a knot in the

underlying wood.
16 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

Mh. W\

FIGURE 23.—End view of hickory log showing stain caused

hy bird pedí.

In factor}' lumber the degradino' effects are determined by the distribution (which affects the

yield of clear cuttings) ratlier tlian from size,

character, and condition of the individual knots.

Obviously, large knots will limit cuttings more

than small knots. But a knot in lumber, no matter

how small, will limit a cutting under standard

hardwood lumber grades. Thus, any log knot is

a dégrader in factory logs. Even "surface" log

knots, arising from epicormic or sprout limbs,

cannot be discounted. Although a particular log

knot of this origin may taper out at a shallow

depth, it generally indicates successive layers of

?^^L

FIGURE 24.—Small holes

lumber knots for an indefinite depth into the

wood.

In construction logs the degrading effect of a log

knot depends upon an entirely different set of circumstances. If the underlying lumber knot is

larger than one-fourth of the face of the largest

included timber (measured on the small end ai the

log), or if it is ver}' rotten, it is definitely a defect

because it will affect the strength of the piece,

( ruides to the breaking point between the two conditions are as follows : A sound log knot is a defect

in a construction log if the diameter of the log

knot collar at the jîoint of occurrence is greater

FIGURE 2r,,_Sound log knot.

FIGURE 26.—Unsound log knot.

F-4555t>7
GRSSBTTBTECTS IN HARDWOOD TIMBER AND LOGS 17

than one-third the diameter of the log at that

point. For log knots from epicormic branches

which can be absolutely identified as such, this

limitation can be increased to one-half the diameter at the point of occurrence. This is because of

the extremely rapid taper which takes place between the log surface and the point of origin.

Lo^ knots smaller than one-third to one-lialf of

tlie diameter can be disregarded as degraders if

they do not occur in whorls equaling the effect of

the larger log knot, and provided they are sound.

If they are m whorls, then the com'bined effect

must be considered, and a whorl of small log knots

the sum of whose collars exceeds the limit for the

single large one is a log grade defect.

Unsound log knots are judged by the same rule

as sound ones, so far as size is concerned, but the

rot cannot extend more than 3 inches into the included timber. In practice this means that an unsound log knot of acceptable size is a dégrader if

the rot extends into the log for a distance exceeding one-fifth of the log diameter.

Jn local-use logs the only limitation on lumber

knots is that they must not extend across individual pieces of lumber. A good rule is that a log

knot is a grading defect if the collar diameter exceeds one-half the diameter of the log at point

of occurrence or if the aggregate of a whorl of

smaller log knots is of equal effect. Other log

knots, even if unsound, maj^ be disregarded.

LIMBS

Definition.—A limb is a branch or subdivision

of the stem or an outgrowth from the stem (fig.

27). It may have been one of the original

branches, starting at the pith of the main stem, or

it may have started later from dormant buds at

varying distances from the pith. These epicormic

limbs may be identified by their tendency to grow

almost vertically parallel to the main tree stem,

and often by an abrupt increase in diameter at the

base. They retain a smooth or juvenile appearance of the bark to a much larger size than a

primary limb.

Occurrence.—lÁmhm^^ varies with growth or

development habit of each species. It also varies

with conditions of growth such as spacing and site,

age and size, competitive position, and health or

vigor. Species generally most free from limbs are

cottonwood, túpelo, yellow-poplar, and the ashes

and basswoods. Oaks—particularly black oak on

poor sites, scarlet oak, pin oak, and sometimes the

water oaks—are very limby.

Significance.—lAmh^ will be reflected in generally sound knots in the sawed product. Since

tftey degrade factory lumber regardless of size,

condition, and character, they are log grade delects 271 factory logs. In construction logs and in

l^^aUise logs the same rules apply that relate to

og knots; namely, there is a size limitation. If

tne limbs are above the size limitation or if smaller

and arranged m whorls, they are defects which

FIGURE 27.—Limbs.

may prevent a log otherwise qualified from being

put in one of these two classes. Otherwise, they

may be disregarded.

OVERGROWTHS

Many log surface abnormalities appear to be

only breaks in the normal bark pattern of the tree.

Log knots (resulting from broken or cut

branches), mechanical wounds (as from ax blaze

or logging), and discrete holes such as those made

by sapsuckers or insects are common causes of this

type of abnormality. As the tree develops, they

are covered over by callus tissue and finally engulfed in the wood. As the years pass, the bark

reforms over larger ones and the presence of a

blemish in tlie wood is shown only by a deformation of the general normal surface contour. A

Inimp ( \). (i ) is an extreme example of this.

Deeply buried smaller features may leave no external evidence. For many years, however, most

features—until they become so deeply buried in

the heart as to lose significance as product defects

in the quality zone—leave on the surface of the

tree or log either a definite structure of callus, or

an identifiable break in the normal bark pattern.

'S'í¿c/í features are classed a.s overgrowths. They

actually are phases of other log abnormalities described elsewhere. Yet, because many of them
18 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

FIGURE "JS n • r-465564-75

pveigrowtÏÏrwateî'ïrcnifs'pVÎ^^^^^^^^ importance in judging the quality of hardwood timber: A and B,

to deeply buried W knot P Í^-\r n^ ^°°^ ^"'* ' ^"^""^' '^"'•^«1 = ^ «nd Ö, overgrowth in blackgum due

overgrown epicortnic buds' surroundT^^Tn I^'""'""'' ."°'^' °" '^'^'^^ ^^"^ l^^<ii"& *" I'^^^ber knots; G and ^,

^^ and ¿, large grub^ated^vrSt^^^^ '^'•^"'^^ ' ' -^ ./, bird peck in forked-leaf white oak;
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 19

FIGURE 29.—Overgrowths caused by knots.

F-465628-30

are inconspicuous and easily overlooked, and because they are the least understood of all the

hardwood log surface abnormalities, they are considered together for emphasis.

A recently overgrown log knot is an example of

a very conspicuous and easy-to-recognize feature

in this class. Less easily recognized are evidences

of old insect work. Such damage may be so

hidden that the only indication of its presence is

a general appearance of the bark, which to the

trained eye signifies a need for close search for individual overgrowths. The importance of overgrowths in the evaluations of hardwood factory

lumber logs in particular cannot be overemphasized. Appraisal on the ba^is of all other log

grade defects would, in most situations, be fallacious if overgrowths were not consistently recognized and given full weight as product defect

indicators (fig. 28).

Overgrowths may be grouped into four relatively distinct classes, three reflecting origin

(knots and associated bark pockets, insect work,

sapsucker damage), and a fourth (bark distortions) of uncertain origin.

Overgrowths Related to Knots and

Associated Bark Pockets

Definition.—The most obvious overgrowths are

those indicating overgrown or buried log knots

and associated ingrown bark (fig. 29). Where

single log knots are involved, tlie overgrowth in

the early stages of development takes the form of

the underlying log grade defect. Wliether the log

knot is covered over with callus tissue or there is

a circular excrescence of callus tissue around it,

there still is a separation between this tissue and

the normal bark. The log knot is gradually engulfed as time goes on, but for many years definite swirls or lines form on the bark, making a

characteristic pattern of rouglily concentric circles most distinct at the base.

These patterns, which are so definite that there

can be no mistaking their cause, persist until the

log knot becomes a lumber knot so deeply buried

that it will not be found in the quality zone.

From tliis stage on the characteristic bark signs

gradually disappear, and the deeply buried lumber knot is evidenced by a bark distortion which

may be merely a faint break in the normal bark

pattern. When clusters of small log knots (generally from sprout growth) with associated bark

pockets are involved, a small rise or slight bump

may be formed during the early stages of overgrowth. The bump or rise resembles that covering a large single log knot. These small bumps

sometimes run together to form a sort of rosette.

The final stages are similar to those of the single

log knot, except that the bark distortion is apt to

be wider and more irregular.

Occurence.—There is no relation between such

overgrown log knots and species except that some

species are limbier than others. This class of defect is often overlooked in well-stocked stands of

rapidly developing, well-cleaned second growth

and especially in upper logs. Recognizing overgrowths in sucli stands is particularly important

because, although general appearance may be one

of clearness of bole, the underlying knot is just

beneath the slab.

Signißcnncc.—Each log knot-c a u s e d overgrowtli indicates an imperfection (knot) in the

quality zone of the underlying wood. In factory

logs each is a log grade defect. In construction

logs the overgrowths can be disregarded except

when they are of abnormally large size or, if

sniftll, when wliorled. Overgrowtlis of

class can be disregarded in local-use logs.

this
20

U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

;iiiiiiiiiiiiBi|nnnnnnnniillliniinil]

F-503350-51

FIGURE 30.—Overgrowths caii.sed by borer.'! : A. Rouiidheaded borer exits : B, carpenter worm entrance and exit or borer

entrance.

Overgrowths Related to Insect Attack

Large Borer and Bark Scarrer Work

Definition.—Common ixncl extremely importiiiit

distinctive bark irregularities are those coverin<r

holes caused by the work of such insects as wood

borers (fig. 30) and bark scarrers (fig. ?>1). The

hotter results in irregularly puckered scars covering the entrance hole and surrounding area of

bark destroyed by the feeding larvae. The size of

overgrowth varies from 2 inches to ;! by 5 inches

in dimension. Roundheaded borer exit holes will

be covered by a sharp pucker consisting of a pitted

core with callus tissue and distorted bark extending over an area % to -2 inches in diameter, (xenerally, borer-caused overgrowths in the bottom

lands involve carpenter worm work, while in the

uplands they involve roundheaded borer work.

The covering of bark scarrer work usually

shows as a vertical slit from % to :) inches long

mm '^ff "'. Y'" "'' '^"^^^ ^'^^^«- The total max"

3Jr{f T' i' ^•^'1^''^'^">' '-^'^«^^^ -^/2 inches

vellmP t fi'' ^''"-' THe most extreme deledeiTi '^ *'"' ^-^'P^ "*'f<^'^ l«oks like a small

SCUP. nï"'' '"TY^- I" ^-^'^^ ^^=iii^s projecting

nî V l,?i 'T''^ ^^="'1^ ^^ «•" snrrounding area^

bárL tV'^'T- ^\''^^"'-^'«'>^- These ccm^cealing bark scales, jiarticularly in mature trees, may con"

tain holes Vs to 14 in<^l^ in diameter, or exhibit

numerous transverse breaks, cracks, or ridges

which indicate that overgrowths are present (fig.

5(1, p. 3t)).

Another type of bark scarrer overgrowth (fig.

3"2) closely resembles the overgrowth of the

roundheaded borer exit hole, making a precise

distinction between the two difficult. Moreover,

in some situations this general type of scarrer injury causes numerous breaks in the cambium,

many of which are little larger than coarse bird

peck and which result in finely puckered overgrowths that are hardly as conspicuous as individual coarse bird pecks. Nevertheless, the usual

overgro\\-th of this sort is slightly larger than that

associated with rounclheaded bore exit holes and

is generally less regular and clean cut with more

radiating lines in the pucker.

Occurrence.—This general class of insectcaused overgrowths is definitely related to species,

aiul within species to site and history. Although

widespread over the entire East, it is most prevalent in the South, especially in the valleys of the

lower Mississippi River system and the lower

Coastal Plains. Occurrence is closely related to

sites, being affected not only by the sharp differences between the alluvial and upland situations,

but also by the widely varying growth conditions

in the lowlands.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 21

I^iCH^s. i

I

^

F-503352-53

FiGUEE 31.—Overgrowths caused by bark scarrers : A, Surface : ß, interior ; bark pocket l)ut no hole.

The oaks and some of the hickories are the

species most susceptible to attack. Of the hickories, sweet pecan is an exception and is almost

entirely free. Within the other hickories occurrence is likely to be most important on poor, dry

sites, whether lowland or upland.

In the oaks three groupings can be made. In the

first group are those usually free from this type of

overgrowth. They include cow, Delta post, northem red, Shumard, swamp white, and cherrybark

oak. (Damage to cherrybark and cow oak is

mainly confined to bark scarrer work, which is

occasionally serious in overmature trees or on poor

sites.) In the second group are those rather generally infested—laurel, scarlet, overcup, blackjack,

chinkapin, and chestnut oak.'

■■ For discussions of these relationships see Putnam,

.lohn A., Furnival, George M., and McKnight, J. S. Management and inventory of Southern hardwoods. U.S.

Dept. Agr.. Agr. Handbk. 181. 1960.

WïïPl '|||||||TITI'I'I'I'ITI'

'21 '3

F-502321-22

FIGURE 32.—Another type of bark scarrer overgrowth, easily confused with borer exits: A, Healed scar (1 by 1%

inches) ; B, surface of wood beneath scar shows ingrown bark but no penetration of wood.
22

r.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

The third group includes those m whicli the decree of dam'ige is dependent upon the specific

nature of the sfte. The group may be divided into

wo subgroups. The first includes those often

found both ¿n better drained low ands (principally terraces and second bottoms) and on rich

Spla^nd sites. It includes forked-leaf white,

black, southern red, post, and shingle oak. Insectcaused overgrowths in this subgroup are most

likely to be found in timber from dry, poor sites,

such as exposed high slopes, ridge tops, ami most

Coastal Plain pine sites. On normally good hardwood sites insect damage is usually slight or

absent in these species. White oak is especially

free on true hardwood sites, but on pme sites of

the lower Coastal Plain it is usually badly

damaged.

Occurrence of these overgrowths in the second

subgroup (Nuttall, bur, willow, pin, and water

oak—typical flood plain species) usually varies

more widely than in the terrace and upland

species. The timber is likely to be very bad when

the trees are growing in hardpan flats on terraces,

in back-water areas where there is prolonged inundation and tight clay soils, and on dry upland

sites away from alluvial soils. Site variations in

general and soil variation in particular, together

with degree of freedom from .fire injury, may

drastically reduce or increase occurrence in these

species. These species are likely to be relatively

free from such defects on good flood plain sites,

but only on such sites.

In this third group are many other hardwood

species in which insect-caused overgrowths may be

found, particularly in trees on unfavorable sites.

However, the definite relationships or the plain indicators found in the oaks are not present, except

that green ash in poor, deep swamp sites may

show serious borer infestation over wide areas.

Insect-caused overgrowths are also likely to be important in extra large, overmature, and decadent

sycamore and cottonwood on poor dry sites. Table

1 o-ives a general summary of these complicated

I'elations.

Signtßcnnce.—Grub- or borer-caused overgrowths mean channels in the wood and generally

bark pockets at the points of entrance, emergence,

or both. The boles indicated by this type of overo-rowth are rarely under i/4 inch in diameter and

are often associated with rot and stain. In factory

lumber each channel or hole in a board is a product defect, and m factory logs, therefore, each

overgrowth is a log grade defect. In construction

logs, unless the holes are very numerous (in which

case there are usually accompanying defects of

other nature, such as loose heart, shake, and rot),

the holes and channels are not considered in grading the product and therefore can be disregarded.

They can also be disregarded in local-use logs.

Bark scarrer-caused overgrowths, on the other

hand, indicate bark pockets which degrade factory

lumber. The uncertain feature is the plane in

which the imperfection lies. Although the particular bark pocket indicated by the overgrowth

may affect only one or two boards (the result of

cambium excavation), the presence of any such

abnormalities indicates the strong probability of

additional similar lumber defects in different

planes. Bark scarrer-caused overgrowths, therefore, are log grade defects in factory logs but may

be disregarded in construction logs and local-use

logs. It should be noted, however, that heavy

bark scarrer work is commonly associated with

check, shake, and incipient rot. The combination

TABLE 1.—Probability of insect damage in the southern oaks

Species practically

Species generally damaged. Degree of damage dependent upon^—

free from damage

General site quality, fire history, or age Specific nature of site '

Cow 2 Laurel Chestnut White Nuttall Delta post Overcup Scarlet Black Bur Cherrybark 2

Northern red

Shumard

Swamp white

Chinkapin Southern red Willow

Blackjack Post

Shingle

Pin

Water

Damage slight on Damage medium on Damage slight on Damage slight on

good sites and good sites and terraces or second well-drained alluvial

heavy on poor heavy on poor bottoms and good soils and good upones, if burned. ones, if burned. upland sites; heavy land sites; heavy on

if overmature. if overmature. on dry or sterile upland sites.hardpan flats, backwater areas with

tight soils and prolonged inundation

and dry upland

sites.

than allwiLT'''** according to natural site distribution of each species; that is, Nuttall oak is never found on sites other

sites. *^"^ ^^^ ^'^^ ^°"' 03.^' if overmature or damaged, may be badly infested with bark scarrer on poorly drained
i

GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 23

often makes the log worthless for any purpose,

just as in the case of grub damage.

Horizontal Bark Scarrer

Definition.—Another boring insect defect produces a channel i/g to Y^ inch in diameter that

generally follows a horizontal direction across

one-fourth of the tree circumference. The overgrowth is typically a narrow band of callus tissue

from 3 to 10 inches long.

Occurrence.—This insect-caused overgrowth is

found universally in white oak in the southern

Coastal Plains, except on the best hardwood sites,

and sporadically in overcup oak (fig. 33).

Signi-flca'nce.—It is a dégrader in factory htmler logs and can be disregarded in the other

classes.

Overgrowths Related to Sapsucker

Work

Definition.—Overgrowths that cover the peck

holes of sapsuckers (not the usual woodpeckers)

may be recognized by the conspicuous, horizontal

row or belt pattern of occluded holes about onefourth inch in diameter (ñg. 34). Occasionally

the entire log is freckled with such bird peck.

Where the holes are continuous, a horizontal crack

often forms.

Occurrence.—Species most susceptible to attack

by sapsuckers are hickories, elms, sweetgmu, yellow-poplar, and water oaks. The other oaks,

maples, and birches are damaged moderately.

Significance.—Overdowths from sapsuckers indicate imperfections m the wood consisting of

small holes or groups of holes filled with callus

tissue. One attack would cause imperfections

m only one plane and would thus affect only a few

boards in factory logs. However, most trees exhiliiting such features liave been damaged repeatedly over a number of years. The vai-ious degrees

of occlusion and occurrence of horizontal cracks

indicate liow long ago the injury occurred. The

variability of damage makes it clifficult to predict

tlie exact e.xteut. Nevertheless, except for very

large butt logs, it is safe to assume that damage

extends far into tlie tree and atïects a large part of

tlie volume. Thus, these overgrowths must be

considered as log grade defects in factory logs.

Usually the damage does not weaken large pieces

of wood and, therefore, this type of overgrowth

can be disregarded Í7i construction logs and localust' logs.

Overgrowths of Uncertain Origin

Definition.—Overgrowths of uncertain origin

are called bark distortions. These are faint or indistinct but still discernible breaks in the normal

pattern of the bark (fig. 35). As opposed to other

types of overgrowths, they exhibit no characteristic formation which will enable the cause to be

established definitely from bark appearance alone.

They are the result of the burying of any of the

log grade defects already discussed. They may

cover insect damage, woimds, bird peck, or—most

commonly—knots.

Occxirrence.—Bark distortions (as defects)

have the same relationship to species as do their

causes. A smooth-bark tree, such as beech, carries

the evidence of these deeply buried defects on the

bole much more clearly than does a rough-bark

tree like soft elm. Bark distortions are relatively

prominent on young sweetgum. j-ellow-poplar,

cottonwood, and second-growth red and water

oaks.

!^ignificance.—Bark distortions reveal the presence of deeply buried blemishes. It is important

«•-502330-31

FIGURE 33.—Effect of unknown trunk-boring Insect in overcup oak : A, Horizontal bark scar ; B, typical gallery. A

similar defect in white oak is distinctly finer, being only i/g inch or less in width. This defect seriously degrades

most of the white oak in the Coastal Plains piney woods and is the principal cause of prevalent low quality in that area.
U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

FiGUEE 34.-

F-466689

-Overgrowths caused by sapsucker work.

F—455637-38

FIGURE 35.—Bark distortions.

to direct especial attention to them because they

are inconspicuous in their later stages and, consequently, easily overlooked by untrained eyes.

In all stages they can be disregarded as defects m

construction and local-use logs^ but must be regarded as degraders in factory logs under 15

inches in diameter. Significance in larger logs is

another matter. In about half of the logs over 15

inches in diameter the underlying defects are

buried in the heart center. In the other half the

wood blemishes are in a degrading position in the

quality zone. The significance varies with species

also. It is greatest in beech, for example, and

least in hard maple. Altogether, ¡n large factory

logs bark distortions are of such variable degrading eiïect that they can be disregarded.

SEAMS

Definition.—Sëa.m.s are longitudinal radial separations of the fibers in a log or tree, either open

or overgrown with callus tissue (fig. 36). If the

seam is overgrown, bark is usually encased,

tseams are generally caused by wind, lightning,

or trost. They are likely to be found in trees with

cross or spiral grain, or which are buttressed or

leamng, or mternally stressed from other special

causes. ^

. Occurrence-Semis may be found in any speS f^ common in the oaks, ashes, maples,

elms, poplar, birch, beech, and honeylocust.

Jimficance.~The signiñcance of seams depends upon their depth. Often a rot is associated

not o^1v?"ii '^' consideration must be given

/n CLw '' '^"^ ^''^ *^ ^^^ ^'^t^"t of thf rot.

iatid ro7p r'i* ^ ''^"' *^S'*'^^^ ^"th any assofift of tL lí"í "''" "^^ ^«g i«^ i^^^ tl^^^^ «nea degrider ^^.^f"^^^er it can be disregarded as

is reduced to .1 ^T t^P'^' ^^^^ ^^^^^^^ scale eauced to allow for loss of lumber, it is still

a dégrader in that it stops cuttings, in constmction logs it can be disregarded if it enters the largest included timber (as measured on the small end

of the log) only slightly, say one-half inch. If a

sound or unsound seam enters the timber deeply,

however, it must be classed as a log grade defect

which will eliminate the log from or degrade it

for this class of use. hi local-use logs most seams

can be disregarded.

SPLIT

Definition.—A split is a longitudinal separation

of fibers extending deeply into the milling frustum of a factory log or into the included tie or

timber of a log designated for construction use

(fig. 37). A split is generally caused by operational accident or carelessness. Sometimes it results from the release of internal stresses when

the tree is felled; such splits are usually called

"checks."

Occurrence.—The pecans, especially bitter pecan, and the hickories are likely to split at any

time because of release of internal stresses after

cutting; cottonwood, willow, ash, and overcup oak

often split badly at the peak of the growing season. Accidental splits can, of course, occur in a

log of any species, but most trouble is encountered

in the pecans, the ashes, the hickories, and the red

oak s:roup.

Significance.—By definition, superficial minor

splits can be disregarded, hi factory logs splits

extending more than one-fifth the diameter into

the log are degraders even though the portion of

the lumber ruined be scaled out. In construction

logs end splits which do not extend lengthwise

more than 5 inches beyond the trimming allowance can be disregarded. Other splits must be

considered as degraders. In local-use logs splits

can be disregarded.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 25

SURFACE RISE

Deßmtw7\.—A surface rise is a notable, smooth

undulation in the surface of the log or tree bole

which gradually tapers back in all directions to

the normal contour (fig. 38). Because of the nature of this abnormality there can be no minimum

height specification other than the ability of the

eye to notice it. One with the maximum lieight,

however, has a taper of 1 in 6. When the taper

is steeper, the abnormality is classed as a bump

(p. 6). A surface rise is usually the effect of a

small limb stub, a cluster of adventitious buds, or

a deeply buried knot or wound. Sometimes a rise

reflects an earlier crook in the stem.

Significance.—The underlying lumber defects

are so deeply buried that their degrading influence cannot be assessed with consistent accuracy.

Surface rises, therefore, can be disregarded as log

grade defects in logs of all types. It is important

to differentiate between a surface rise and a bump

because the latter is an important dégrader. This

is particularly hard to do when skidding has

rubbed off some of the bark.

WOUNDS

definition.—^^Vounds are openings in the bark

that expose sapwood and sometimes heartwood

FIGURE 36.—Seam. F-455600

FIGURE 37.—Split.

(figs. 39 and 40). Wounds may be either neio or

old. A new wound is essentially a surface injury

in which the exposed adjacent sapwood is apparently sound. Aä\ old wound is a similar injury

either completely open or only partially healed

over. It is generally recognized by unsound sapwood, local hollow, much callus tissue, insect damage, and often stained or actually rotten

heartwood.

Significance.—1\\ a new wound deterioration is

usually not serious, for any insect damage or stain

will be quite superficial. Therefore, under most

conditions and for all types of logs., new wounds

can be disregarded as log grade defects. However, with such species as cottonwood, sweetgum,

hickories, willow, hackberry, magnolias, and basswoods, early deterioration of wounds is apt to

occur ; if it does, this must be considered.

The seriousness of an old wound varies considerably with locality and with species. In some

species exposed heartwood may completely heal

over before serious injury occurs. Nevertheless,

since old wounds are usually associated with stain,

rot, and insect damage, the affected area is a grading defect in both factory logs and can.stniction

logs, except in the rare cases where it is superficial. In the factory logs, even if scale deduction

is made to cover the area involved in worthless

wood, the area will stop a cutting. Old wounds

can be disregarded in local-use logs.
U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

FIGURE 38.—Surface rise. FIGURE 39.—New wound.

Log End Abnormalities

The log abnormalities discussed heretofore have

been those visible on the surface. As has been

pointed out, these usually reflect imperfections in

the wood. Sometimes the cross sections of these

will show in the end of the log. For example, the

effects of bird peck, grub work, advanced rot,

knots, bark pockets, wounds, seams, flutes, and

many other surface abnormalities can often be

seen on the ends. These and similar blemishes for

which there are surface indications are not reconsidered in connection witji so-called "end abnormalities," with one exception. This exception is

made for grub channels, the cross or longitudinal

sections of wood-boring insect channels with definite and recognizable entrance and exit holes on

the surface.

The log end may also reveal imperfections

which normally have no surface indicators.

These are the so-called "hidden" defects that demand local experience for their appraisal in standing timber.

Many of these end features are somewhat different from other product defects in that they are

otten admitted to a certain degree in the products,

'UKl m that their degrading effect is often based

on concentration rather than presence alone.

Sometimes their effect is covered by special grades

mïillr"'* u' ^^^'"'^'^ ''' '^''' P^duct without

Snt 1?"' ^l'^ ''^'''^' '^i-'^^g '^ ^-e^^^ced product price. Also, their location is important. Some

which occur in the heart center only may be disregarded in one type of log; in another type of

log the same imperfection in the same position

will mean a drop in log class or require culling

the log.

F-455605

FIGURE 40.—Old wound.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 27

Many of these features are difficut to judge because they are found on one end of the log only,

and the observer must use considerable judgment

in determining how far into the log the blemish

extends. Many are in the class of the scalable

defects, and in judging their significance as a log

grade defect, the relation to the particular product for which the log is best suited must be carefully considered.

DOUBLE PITH

Definition.—"Wlien a tree bole forks and a log

is cut just at the base of tlie fork, the end of the

log will seem swollen ; the top will have two separate pith centers, often separated by a bark

pocket. This condition is called double pith (fig.

Significance.—Double pith leads to cross grain

in sawn products, together with a split or potential split from the bark pocket. The general

approximate effect is that of two large knots. In

factory logs double pith is not a dégrader ; nevertheless, the related seam and any enclosed bark

should be treated as in the case of fork (p. 11).

In construction logs double pith is a dégrader.

Double pith is not a dégrader in local-use logs.

In standing timber double pith may be disregarded if the section including it can be cut out

so as to leave logs of sufficient length to fulfill the

minimiun requirements of the log class.

GREASE SPOTS

Definition.—Grease spots are limited, shadowy

streaks with a dirty "greasy'' look. They are

sooty or brown in color and surround oval, frassfilled insect channels y^e inch in diameter (fig. 42).

Occurrence.—Grease spots occur principally in

overcup oak and locally in diestnut and white

oaks. They are generally found in overcup oak

in backwater flooded areas of the larger river bottoms and in the other species on poor, dr}' sites

with a bad fire history.

Significance.—In factory logs they are log grade

defects if in the quality zone ; in the other classes

can be disregarded.

GRUB CHANNELS

. Definition.—Grub channels are round holes or

irregular channels of varying length, from % to

1 mch in diameter (fig. 43). They are made by

wood-consuming grubs that hatch from eggs laid

m the bark of the living tree and work their way

mto the log and later back to the surface. The

Mies are cross or longitudinal sections of the

channels.

Occurrence.—K single hole or channel may

3how, or the end of the log may be literally ridtüed. Although grub channels may occur in any

species, they are found most often in the oaks,

particularly in overcup oak, chestnut oak, and the

Water oaks. As discussed under insect-caused

ff

FIGURE 41.—Double pith.

FIGURE 42.—Grease spot. Cross section of 28-inch overcup oak log with signs of "grease spot" damage. Dark

lines and spots indicated flatheaded borer galleries and

associated stained wood. All lumber from this lofc

graded "sound wormy" from grease spot defects.
28 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

overgrown abnormalities (p. 22), species-site rektionsliips are important clues to their probable

occurrence. , , i x i

i^¡an;f-canee.—V^hen gvnh channels :;re tew and

scattered or when a concentration is conhned to

the heart center, they may be disre^^arded m factoid logs. Careful search, including thorouo'li

examination of the log surface, should be made to

ensure that the coucentration is so conhned.

Wlien it is not, it is a grading defect. In extreme

cases and when found in conjunction with other

degraders, grub channels may cause the log to be

cufled. In comtruction logs concentrated grub

channels in any part of the log are a log grade

defect; scattered ones are not. Grub channels

can be ignored in local-use logsGUM SPOTS

Definition.—G-am spots are accumulations of

gum occurring as small patches, streaks, or pockets. They may be related to bird peck or other

injury to the growing wood or, as in sweetgum,

may be simply impregnations of the wood fibers,

related to presently unidentified pathological disturbances. In sweetgum they can seldom be identified except on the end of the log.

Occfurrence.—Gum spots are found chiefly in

black cherry and sweetgum. Probability of occurrence in sweetgum seems greatest on sites within the lower Coastal Plain.

Significance.—In sweetgum factory logs gum

spots are log grade defects when found in conspicuous concentration, for they reduce otherwise

higher grades of lumber. Gum spots in cherry

lumber are admitted to the "clearface" cuttings

without limit and are not a defect in factory logs

of this species. Gum .spots, since they do not affect strength, are not grading defects in construction, logs and local-use logs.

LOOSE HEART

Definition.—Loose heart is the tangential separation of fibers completely around a growth ring

within the heail center or core of the log, in an

area uvnerally not over 6 to 12 inches in diameter

(fig. 44).

Occurrence.—Loose heart is most likely to be

found in bitter pecan, the elms and honeylocust,

and in overcup, chestnut, scarlet, and the water

oaks.

Significance.—The area affected is well defined

and must be scaled out. When loose heart is confined to the heart center, it may be disregarde'^

in factory logs. Although the volume yield will

be greatly reduced, the loose heart will in such

cases ha\e a minimum etfect on average lumber

grade yield. Loose heart prevents taking a tie or

timber out of the center of the log and is a degrader in logs designed for this use. It may be

disregarded in loenxl-use logs if the scale deduction

is within limits. Loose heart is frequently derived

from the release of crooked, suppressed saplings

and follows the original stem form. Thus, it may

have a disastrous effect on small, crooked, or

sweepy logs, often necessitating culling the log.

MINERAL STREAK AND STAIN

Definition.—Mineral streak or stain is an abnormal discoloration—black, blue, brown, or olive

«?S^^^-!"'

tí

4,

FIGURES 43.-<3oneentration of grub chaun/ls* FIGURE 44.—Loose heart.

F-455610
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 29

FIGURE 45.—Mineral streak and stain.

green—usually in variegated or streaky patches

confined to the heartwood (fig. 45).

Occurrence.—It is very conspicuous in soft and

hard maple, yellow-poplar, willow, and the magnolias. It is found generally throughout the oaks,

especially the water oaks, and particularly on poor

sites.

Significance.—In fctctory logs it is a log grade

defect when conspicuously concentrated outside

FIGURE 46.—Pin worm holes. F-455612

the heui-t center. A small amount there may be

disregarded. In the maples, magnolias, and'yellow-poplar mineral stain itself is not a lumljer

defect. Heavy concentrations (mineral .streak),

however, are often a.ssociated with fine check and

sluike, which are piwluct defects. Mineral streak

and mineral stain can be disregarded /'/( con.^frucfion and local-wse logs.

PIN WORM HOLES

Definition.—These are small round holes made

by ambrosia beetles and always somewhat less than

one-sixteenth inch in diameter (fig. 46). Certain

types are exceedingly minute. Those found in

some species, notably overcup oak, are so small

that they would easily be overlooked if it were

not for accompanying faintly discolored threads

or spots.

Occurrence.—They are most prevalent in, but

not confined to, post oak, overcup and chestnut

oaks, ashes, and yellow birch. Black cherry,

elms, hickories, pecan, yellow-poplar, beech, sweetgum, túpelo, magnolias, cottonwood, and willow

are relatively free. When pin worm holes occur,

they are invariably numerous; practically all of

the wood in the log will be affected.

Significanre.—In furtory logs pin worm holes

are log grade defects, and special grades of lumber with lowered value are used for the species in

which occurrence is most common. Pin worm

holes may be disregarded in construction and

local-use logs.

RING SHAKE

Definition.—Ring shake is a tangential separation of the wood fibers along parts of the annual

rings (fig. 47). Sometimes it is confined to definite sections along the outer rim of wood, sometimes it is confined to the center, and sometimes it

is found all through the log. Important ring

shake is often so fine as to be invisible in green

wood, and shows up only when the wood is dry.

Occurrence.—Although ring shake is definitely

related to species, it is not found on all trees of

any species. On the other hand, it may be found

in some trees of every species. It seems especially

prevalent in overmature, leaning, toppy. sweepy

tin)l)er. Ring shake is most common in the butt

log and may result from a serious butt injury. As

good second-growth timber stands develop, the

occurrence of ring shake will be greatly reduced.

Today, however, much of the old-growth bitter

pecan is shaky. Ring shake is also serious in overmature sycamoie, túpelo, and elms, and in overcup

and chestnut oak from poor sites.

Significance.-—In jnctory logs ring shake confineci to the heart center or to definitely localized

areas in tlie periphery can be scaled out. Ring

shake confined to the heart center is not a grading

defect, but peripheral ring shake is a dégrader because it will stop cuttings. "\^lien ring shake is
U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

FIGURE 47.—Ring shake.

general throughout the log, it is a good reason to

cull the log. It is a grading defect in coiifttruetion

logft. Localized shake can be disregarded in localuse logs up to the point where the scale deduction

for it exceeds that permitted in the class.

ROT

Incipient Rot (Dote)

Deßnitio-n..—Incipient rot is an early stage of

decay. The wood is discolored and weakened, but

does not lose its structure (fig. 48).

Occurrence.~lT[\á\)\(ti\t rot can be present in all

species. In woods of low density such as the magnolias, túpelos, or sweetgum, the decay process advances rapidly.

. Significance.—In both scaling and mannfacturnig, incipient rot is less consistently recognized

and taken care of than is advanced rot (p.—).

incipient rot is generally scaled out, particularly

It extensive or outside the heart center. In fartoryJog, sueh rotten areas when contained in the

heart center or inner half of the quality zone may

be disregarded as a dégrader, whether scaled out

or not, whereas incipient rot in the outer half of

me quality zone is a grade defect. In conMrucT^y'- "i^'Pifht rot is a grade defect, regardless

d s eï;lT\'"^^''r ^'^" '«^- I'l^ipient, rot'may be

that a iÏÏ'; ^¥"^^i«'^ f<^i- i^ ^i«<^s "^t exceed tnat allowed for the class.

FIGURE 48.—Incipient rot.

F-4559W

Advanced Rot

Defniticm..—As opposed to the early or intermediate stages of decay, advanced rot is wood

characterized by a breakdown in the structure to

the point where it is useless (fig. 49).

Occurrence.—There is no particular relationship to species. Advanced rot generally occurs in

definite areas in the tree. A frequent location is

the center. Rot resulting from wounds or knots

is commonly found in the outer rim of wood.

Signißcan-ce.—The significance varies with use

and location. In factory logs advanced rot confined exclusively to the heart center can be overlooked as a log grade defect. The affected section

will, of course, be scaled out. Even though scale

deduction is made for rot, rotten areas in the

quality zone are log grade defects if they occupy

over one-half the cross-sectional areas in any quarter of the quality zone.

In constmction logs advanced rot in the center

is a log grade defect that, except in large diameters, probably will eliminate the log from the

class. Rot in the periphery is also a dégrader,

unless it is so superficial that it will extend into

the included tie or timber in only a few minor

spots not more than 3 inches deep. In local-use

logs advanced rot can be disregarded providing

the scale deduction does not exceed the limits for

the class.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 31

I

SHOT WORM HOLES

Definition.—Shot worm holes are clean-cut

round holes about one-eighth inch in diameter

(fig. 50). They are generally concentrated in

and about rotten heartwood, especially open butt

wounds and hollows.

Occurrence.—They are commonly found in

oaks, hickories, ashes, and occasionally in sweetgum heartwood.

Significance-—Since shot worm holes are generally associated with rotten wood, they are not a

dégrader m factory logs if confined to the already

degraded area. If they extend beyond the bad

section and increase the area damaged, they become log grade defects. They can be disregarded

in construction and local-use logs if the permitted

allowance for associated rot is adequate to cover

the deduction.

SOAK

Definition.—Soak is a moderately discolored

area, dirty mustard yellow, bleached brown, or

didl gray (fig. 51). The wood looks dull, dead,

rough, spongy, and often water soaked or weathered. Although it is considered by some as incipient decay, soak actually is not accompanied by

a softening of the fibers; in fact, they are sometimes embrittled.

Occurrence.—It is most common in overcup and

water oaks on poor sites.

Significance.—Ordinarily no scale deduction is

made for soak. In factory hvmher it is regarded

as equal in etïect to mineral stain or localized incipient rot. When heavy enough to be so considered, soak becomes a factorij log grade defect,

but can be disregarded in construction and localuse logs.

SPIDER HEART

Definition.—Spider heart, is a multiple radial

separation of the wood fibers starting at the pith

center and running out in at least three directions

(fig. 52).

Occurrence.—?)]i\à^T heart is related to species,

size, and degree of maturity. It is common in

scarlet, overcup, and water oaks and is likely to

be found in chestnut oak. It is most prevalent

in large, fully mature or overmature trees.

Significance.—Spider heart will ruin the products in which it occurs. If it is confined to the

heart center, it is not a log grade defect in faMory

logs and in local-use logs. When it extends beyond the heart center in factory logs., and when it

it- <

FIGURE 49.—Advanced rot.

F-465613 F-455617

FIGURE 50.—Shot worm holes and associated rot.
32 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

vvr

FIGURE 51.—Soak.

ir-466eo8

FIGURE 52.—Spider heart. F-466ei5

occurs to any degree in construction logs, it is a

dégrader.

SPOT OR FLAG WORM HOLES

Definition.—Spot or flag worm holes are cleancut lióles about I/32 ^^ Vie irich in diameter, typically occurring in pairs (fig. 53). They are

invariably surrounded by an oval or elongated

stained or (in oaks and elms) bleached area or

"flag."

Occurrence.—In red and silver maple, post oak,

and chestnut oak, spot worm will be found in almost every tree over certain extensive areas within

tlie range of the species, but intensity will vary

from tree to tree. In soft elm, beech, and white

oak occurrence is spotty and in most localities

absent. White oak over most of its range is free,

Ijut damage is likely to be found on sites that are

dry or lacking in lime.

Sign ifcanee.—In factory logs spot worm holes

with their accompanying flags are log grade defects except in heavily damaged oaks and soft

maple. In these species the lowered value of such

lumber is recognized by special grades, and the

holes need not be considered as log grade defects

when WHXD grades (Worm Holes No Defect)

are used. Spot worm can be disregarded in constriiction and local-use logs.

WIND SHAKE

Definition.—Wind shake is a single radial split

extending to both sides of the pith (fig. 54).

Sometimes it is confined to the heart center, but

often it will go to the perimeter of the heartwood,

well into the quality zone. Damage is usually

most serious in butt logs, but many times the split

extends the entire length of both the butt and

upper logs.

Occurrence.—Wind shake is most serious in

black oak, southern red oak, scarlet oak, and

northern red oak growing on upland sites in the

south central United States west of the Mississippi River. It is most prevalent on older trees

and possibly will occur much less often as site

conditions improve and good second-growth

stands develop. Wind shake is also found in

some of the white oaks, particularly chestnut oak,

on upland sites throughout the Appalachian region and the remainder of the South. It becomes

serious near the middle of slopes and is worst on

the ridgetops.

Significance.—In factory logs wind shake can

be scaled out, and that which is confined to the

heart center is not a dégrader. Wliere it extends

to the perimeter of the heartwood in logs with

a narrow sapwood band, it is a dégrader because

it will stop cuttings. Most wind shake is so serious that it disqualified the log for the construction

class. Wind shake may be disregarded in localuse logs unless it is severe enough to cause the log

to split open in handling.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 33

FIGURE 53.—Spot or flag worm holes. FIGURE 54.—Wind shake.

Table 2 sitmmarizes the log abnormalities, both stirfaee and end, by listing the effect of each

for each log class as defined in the previous discussion.

TABLE i^.—f'<u!nmf7ri/ classification of Jog abnor/nalities

LOG SURFACE ABNORMALITIES

Abnormalities

Bulges:

Butt

Stem

Bumps :

High

Low

Burl

Butt scar

Butt swell

Canker._ _

Conk

Epicormic branches

and adventitious

bud clusters.

Flanges

FlutesFork

Gum lesions

Holes :

Large

Medium :

Bark scarrer,

fresh.

Bark scarrer,

old.

Birds, light

Birds, heavy. .

Grub

Increment

borer.

Tap

Small

Knots:

Sound

Unsound

Factory

logs

(')-

(')-

Defect

(3)

Defect

0*)

No defect.

0)

Defect

(2^)

No defect.

Defect

No defect.

Defect

No defect.

Defect

--do

..do

(*)-

.do...

Defect.

--do-.

Construction logs

Local-use

logs

n

(')

Defect

0^)

No defect.

0)

Defect

No defect.

.do.

CONO defect.

(=)

No defect,

---do

.do-

-do.

-do.

.do.

.do-

.do.

«-

«-

No defect.

Do.

No defect.

Do.

w.

No defect.

Do.

Do.

Do.

Do.

Do.

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

«

«

LOG SURFACE ABNORMALITIES—Continued

Abnormalities Factory

logs

Construction logs

Local-use

logs

Limbs do (2)

«

No defect-

...do

...do

{*)

(^)

No defect-

...do

{')

(')

Overgrowths:

Knots and bark

pockets.

Insects

Bird peck

Bark distortions.

Seams

SpHts

Surface rise

Wounds:

New

Old

...do

---do

...do

...do

m

{*)

No defect.

...do

(*)

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

LOG END ABNORMALITIES

Double pith

Grease spots

Grub channels

Gum spots

Loose heart

Mineral streak and

stain.

Pin worm holes

Rot:

Incipient (dote)..

Advanced

Shake:

Ring

Wind

Shot worm holes—

Soak

Spider heart

Spot or flag worm

holes.

Q)-

Defect.

(«)-

(«)^

(«)

(')

Defect.

(')

(«)

Defect-

( )

No defect..

(')

No defect-.

Defect

No defect..

...do

Defect

.-_do

.-.do

..do

No defect

.-.do

Defect...

No defect.

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

' Defect if not cut off.

'Defect if large and deep.

2 Defect if large ^ Defect if certain species in\'oh'ed. * Defect if not superficial.

8 Defect if not confined to heart center. ' Defect if concentrated.
34

U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

Evaluation of Timber and Logs

LOG CLASSES AND LOG GRADES

The preceding discussion of lofï grade defects

can now b applied to timber and lo^r evaluation^

A log examiner evaluates a stand tree, or log

within his particular frame of reference. Log

ÄSn is the first step.. This is either a

screening or a grouping operation. In screemng

the obiective is to isolate the trees or logs (a class)

that are suitable for a single purpose. In grouping, the objective is to sort the trees or logs into

groups (classes), each of which is suitable for a

discrete purpose. . • . i i

In either case suitability refers to intended use.

In spite of the wide range of qualities m product

yields from individuals within each class, the log

classes outlined in the preceding discussions are

useftil in making broad sortings of timber and

logs. If nothing further is done, however, economic evaluation of either use classes or defects

can be little more than a guess.

Tlie next step is a grading system. It is a series

of specifications that, for each dmi^, place all included individuals in logical subgroups or grades.

Each of these represents a small range of economic

values (or indicators of these, such as product

grades), has an average value higher or lower

than that of any other grade, and contains individuals with values that are within a stipulated

range. Practically, the number of these grades

must be limited; and is so by the total value range

within the class. In hardwood timber three to

six grades will usually stratify the class to the

point where significantly ditïerent determinations

of probable average value of each grade can be

made. The grading specifications usually consist

of class specifications factors with aclditional

quantitative limitations.

DEFECT EVALUATION IN

GRADING

Grade defects are influential in most log or tree

grade specifications. Heretofore, in this publication each log grade defect was discussed independently of log grade consideration. The implication may have been that each defect bears

equa weight as a quality determinant ; that is, a

small log knot is equal to a large log knot ; a large

log knot IS equal to a seam; a seam is equal to a

burl; and a burl is equal to a concentration of

grub channels in the end. With local-use logs

this question is unimpoi'tant because there are so

few clegraders.

For con.struction logs the implication that one

grade defect is of equal weight with another will

also probably hold, for the major influence of log

grade defects appears to be either to admit or exclude the logs from the class. For example, the

efi^ect of an extremely large log knot or of loose

heart would be equal in that either would render

the log unsuitable for construction use.

In factory logs, hoAveA^er, the situation is less

simple. Here the major efi^ect of log grade defects

and associated lumber defects is to limit the area

of clear-face cuttings. The effect of not observing the cutting limit is to degrade boards which,

without the particular blemishes, would be of

higher grades. Eelation of degraders to log size

is important because" it is common practice to eliminate or segregate lumber defects in wide boards

by ripping. The effect of blemishes can be minimized in this way only if the resulting boards are

within the width limit for the grade specified in

the rules ( see appendix, p. 38).

In principle, a very tiny lumber knot is equal

in degrading effect to a large one. Nevertheless,

a run of factory logs may yield enough wide

boards from which small lumber knots can be eliminated, so that the mere presence of small log

knots may not actually mean low-grade boards.

Thus, it may be necessary in logs of large diameters to discount log grade defects that indicate

very small lumber knots, whereas full weight may

have to be given to large log knots on logs of all

sizes. Other grade defects in factory logs may

have the effect of degrading all of the lumber in

the log to a very low point. For example, if bird

peck is very heavy, the procedure might be to give

it the ultimate significance and consider that, even

in the absence of all other log grade defects, it

would relegate the log to the lowest factory grade,

if not to a lower class. The same would be true

for mineral stain.

Thus, evaluation of the degrading effect of log

surface abnormalities, that is, whether the effect

is partial or full, or whether the abnormalities are

considered individually or collectively, must be

based in a log grading system that will incorporate

not only individual log defects, but also their relation to distribution or size requirements of the

product specification and to the other major quality determinants such as size, crookedness, or position of the log in the tree.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 35

General Appearances That Warn of Log Defects

LOG GRADING SYSTEMS

Research-l)ased specifications for factory class

logs are contained in the Forest Products Laboratory publication D 1737 titled "Hardwood Lop

Grades for Standard Lumber." Copies (>f this and

references to other publications dealiiio- wirli

specifications and «grading systems for other log

classes and for trees can be obtained upon request

from any Forest Service forest experiment

station.

Sometimes a log or tree can be evaluated by

weneral appearances: certain conspicuous warning signs may herald the presence of specific log

grade defects.

SIGNS IN STANDING TIMBER

There is a definite relationship between timber

quality and site condition or histoiy of the stand.

Poor site, past fire damage, and overmaturity ai-e

often clues to the presence of such defects as insect

damage, shake, or stain.

General condition and appearance of individual

trees in any given locality serve either as specific

guides to lumber defects' that give no other external indication of their presence (shake or

mineral stain, for example) or as a warning to intensify search for important log grade defects

(such as bark distortions) which cannot be seen at

a glance. To appraise basic difi'erences in appearance of standing tiinl)er re(]uires training and

familiarity with eacli s[)ecies over a wide range

of conditions. liut keen ob.servation and practice

will enable one to detei-mine and recognize the

characteristics of sound healthy trees and, by comparison, those of trees likely to be defective.

Obvious clues to decadence are stagheadedness,

bad fire scars, and large open wounds. Less conspicuous but of the same nature are dry tops, dead

limbs, healed scar.s, and rotten knot holes, often

overgrown except for a gaping oozing center.

Such features indicate decadent timber that may

carry inconspicuous and unheralded defects like

bark pockets, stain, and spot worm holes. ^^Hien

.such obvious general features are present, degraders may be expected in great numbers. Evidence of these in the form of small overgrowths,

often partially hidden under extended but broken

bark scales, will generally be plentiful and easily

located upon close examination.

In addition to the obvious features indicating

decadence, less obvious genei'al appearances are

very important signs of probable log grade defects. Color, thickness, and configuration of bark,

particularly if coupled with evidence of lack of

vigor (dead limbs, thin top, and poor foliage), are

among these (fig. 55).

In general, al^normally dark or abnormally

light bark is a bad sign. In hickories, cherrybark

F-45B618-20

FIGURE 55.—Good, medium, and poor conditions of three willow oak trees, as indicated by bark characteristics.
36 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

oak, and the water oaks, early stages of deteiioration are evidenced by a darkening of the bark,

usually accompanied by a thickening and

roughening. In extremely advanced stages ot deterioration the color trend in these species reverses, and the bark bleaches out to a dead, light

oray and scales off to some extent.

"^ In species with bark normally soft and corky,

such as yellow-poplar and sweetgum, the darkening is accompanied by a "plating" and smoothing

out of the bark. On the other hand, defective

white oak timber in all stages of deterioration is

indicated by a lightening of color and a thinning

and scaling off of bark.

In all species bark looks dry and lifeless when

vigor is lost. Wiere such conditions attract at- •

tention, close inspection is necessary if important

log grade defects are not to be overlooked. The

relation of timber condition to appearance is definite and sometimes so extreme and positive that

an experienced observer has no difficulty in appraising the degree of deterioration solely on this

basis.

Nevertheless, poor general appearance of bark

is not an absolute indication of degraders of any

specific kind. Yellow-poplar, sweetgimi, basswoods, and túpelos are rarely subject to insect attack (yellow-poplar in some localities is liable to

severe attack by ambrosia lieetles, the damage being referred to at times as spot worm, grease spots,

black hole, calico poplar). In these species poor

bark appearance generally indicates slow growth,

approaching maturity, or if localized, rot. In

fact, an area of poor l)ark in these species is as

good a sign of rot as is a butt or stem bulge.

On the other extreme are the oaks and the

hickories. Here poor appearance, altliough a sign

of lower vitality, does not reliably indicate specific location or extent of unusable material. It is,

however, an almost in\-ariable clue to hidden or

obscure bark distortions. Close inspection of the

bark of poor trees of these species will often reveal

scattered, medium-size, dry holes that penetrate

the bark scales but do not lead into the wood. It

niay also reveal that abnormal roughening is an

effect of numerous horizontal breaks or cracks in

the bark ridges or scales. In other cases bark

cracks and scales containing holes will generally

indicate msect-caused log grade defects (fig. .56)

In most cases other log grade defects will have

been noted before the examination has gone that

In other species such as sycamore and the ashes,

túpelos, and maples, the significance of bark appearance IS quite variable. In all species, howintenS?' 'I'T''''''^ ^^ppearance should lead to intensive search for degraders.

defervi'lr ^^P^'' ''* ^"^"^^ ^'"'^ discolorations

ice" Ju'r- ^"" '^ '^'^ so-called "tobacco

brown snW '"''"-f ''"''»"' "S^^^^"y ^^=»i^P t^=^i-k

"P and down the bole. It is unmistakable

F-455eZl-22

FIGURE .56.—In the oaks and hickories holes like this one

(left) call for careful search for the actual dégrader.

The hole was made by an emerging adult insect, and

beneath the scale (right) is the overgrown evidence of

its presence.

evidence of fresh insect damage and can be disregarded unless the splotches are very numerous,

underlain with holes extending into the wood, or

accompanied by bark distortions typical of longestablished infestations.

The other type of local discoloration is a large

patch or streak beginning at a broken top, or an

open wound or knot hole in the main stem and

running down the stem. When coming from a

broken or hollow top of the major stem, the discoloration is usually an overflow of rainwater.

When the discoloration begins elsewhere, it is

caused by water seeping from a pocket of rot.

However, the mere seeping or running usually

indicates that decay is not far advanced, or at

least that the affected section is not an extensive

hollow. Ordinarily the rot will not pass the next

lower fork or body node. When the discoloration

is found on the merchantable stem, however, it is

a log grade defect if not cut out.

SIGNS ON END OF LOG

The lumber defects underlying surface abnormalities sometimes show up in the end of the log.

This fact is particularly useful where logging

operations have scraped the log so that overgrowths, in particular, are hard to find. If previous inspection has found no surface indication

of the associated lumber defects, grub channels

and bark pockets in the end of the log call for a

recheck of the surface. The ends of very large

logs may give positive indication of heavy insect

infestation, the external signs of which have been

overgrown so long as to be obliterated. In such

cases, because the affected area in the quality zone

represents such a large source of the potential

high-grade lumber, the end features themselves

must be evaluated in appraising quality. Otherwise, they merely warn that a recheck should be

made.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS

Indications of Deterioration in Dead Timber

or Stored Logs

37

Since timbermen frequently are concerned with

dead trees, or with logs that have been left in the

woods or stored for a lengthy period, it is important to discuss briefly the indications of deterioration found in such material, so that they can be

distinguished from those found on live trees or

freshly cut logs.

Hardwood logs, particularly in the South, are

highly susceptible to deterioration from insects

and fungi. In summer logs left more than 2

weeks begin to deteriorate so rapidly in some areas

that even "hot logging" will not prevent damage

to some species. Operations for hickory, ash, and

persimmon for dimension specialties are frequently suspended in late spring and early summer because of borer activity. For all other

species hot logging is a necessity during this

period. In the deep South insects may cause

damage the year round.

Among the first to infest logs are the ambrosia

beetles. They start working almost at once in

exposed sapwood on the ends, or on spots where

the bark has been knocked otf. Later, they may

go through the bark and attack the remaining

sapwood and sometimes the heartwood. Their

holes are so very small that it is easier to spot a

pile of flourlike "frass" than to see the holes

themselves. Ambrosia beetles are particularly

bad in sweetgum, maples, oaks, and yellow-poplar.

Their work degrades the lumber. Like shake,

any indication of it ("wonns" in the trade) generally renders a shipment suspect in the eyes of

the buyer and puts the seller in an awkward

position.

Other insects, especially bad in the ashes and

hickories, pecan, and persimmon, are the roundheaded borers. The grubs of these insects cause

degrade by making medium-sized holes throughout the wood and often require culling the log.

Stain-causing fungi come simultaneously with,

and some are introduced by, the ambrosia beetles.

The first effect is a rather even, sooty blue-gray or

black discoloration of the wood. Later a felty

surface may develop. Stain proceeds under the

bark from the ends and through wounds. In very

early stages it does not degrade lumber, although

It affects its salability. In later stages stain definitely degrades lumber unless it is specifically

permitted by the grading rules.

After stain come "flowers." These are whitish,

yellowish, brownish, or grayish variegated mosaic

efflorescences, usually—though not necessarily

superimposed on the stain. They are often evioence of separate fungi which cause rot. Since

tney are commonly accompanied by light mustard-colored or gray bleached streaks in fhe wood

flowers are considered in the trade as incipient

rot and will not be admitted into cuttings. It is

general practice to trim 1 to 2 feet off the ends of

boards cut from logs that show flowers and yellow

streaks on the end- Although sweetgum and the

túpelos are most susceptible to stain and flowers,

sapwood of most species will be attacked. The

water oaks are also hit hard because of their open

pores.

On soft maple and on the hickories, elms, and

hackberries a fungus causing an inconspicuous internal rot starts quickly. This fungus gives no

surface evidence of its presence until it has caused

such advanced interior rot that the log is worthless. At this time the wood is weak, yellowish,

exhibits black, threadlike lines, and looks dry and

bleached out. The surfac« of the log may still

appear sound and merely weathered. Other fungi

betray their presence by fruiting bodies (toadstools and brackets). These generally indicate

advanced rot and a large scaling deduction, if indeed the log is usable at all (fig. 57). -

The ends of any logs left out in the weather will

check or split. Ashes, hickories, pecans, and overcup oak are prone to end-check throughout the

year; in other species degree of end-checking

F-455624

FIGURE 57.—Brackets are a sign that rot has made at

least the sapwood useless. The heartwood may remain sound for a considerable time, but very careful

examination is needed to determine the extent of the

rot.
38 U.S. DEPARTMENT OF AGRICULTURE HANDBOOK NO. 244

varies with the season. In good drying weather

end-checking in cottonwood, the pecans the hickories, and the oaks is particnlarly l>ad. denerally, end-checking is progressive, with tlie speed

and severity rehrted to rate of drying.

In most logs of most species end checks are not

serious, for they generally go less than 1 foot into

the log. On logs of susceptible species they may

extend well into the center and cause .serious damage. Such extreme checks are equal in effect to

splits. The importance of checks is also related

to log size. Small logs may be completely ruined

by checks which in larger logs would be

unimportant.

Appendix

BASIC SPECIFICATIONS FOR STANDARD HARDWOOD LUMBER GRADES

[Adapted from the rule book of tlie National Hardwood Lumber Assoc, Cliicago, January 19G2; published by permission

^ of the Association 1

Minimum -equirements

Grade

Length ' Width

Yield of

rough lumber

in clear-face

cuttings

Size of cuttings Cuttings 2

Firsts and seconds - -

Feel

8

6

4

4

Inches

6

4

3

3

Percent

8.3>'3 4"X5' or 3"X7',_

A''!; mber

1-4.

Selects ^

1 Common.- _ -_ __ _ _ 66%

50

4"X2' or 3"y3'__

3"X2' -

1-5.

2 OrtmmoTi 1-7.

Sound wormy ^

3A Common 4

4

3

3

33"3

= 25

3"X2'

li^."X (variable

length).

Xo limit.

3B Common To give 36 square

inches.

' Percentage of short lengths limited by grades; e.g., in

firsts and seconds, only 15 percent can be 8 feet to S) feet;

in 2C, 10 percent can be 4 feet to 5 feet.

^ Number varies with surface measure (s.m.) of piece;

e.g., IC with s.m. of 5 feet to 7 feet, 2 cuttings allowed;

in IC with s.m. of 11 feet to 14 feet, 4 cuttings allowed.

' Better face 91% percent clear, 1 cutting; reverse side

of cuttings sound for pieces 2 feet and 3 feet (s.m.).

Better face is seconds; re\'erse side of cuttings sound for

pieces 4 feet + (s.m.). Better face is seconds; reverse

side of board 10.

* Full log yield of IC and Better, with worm holes,

knots, etc., not over '4 inch and stain, admitted into

cuttings.

* Sound cuttings.

COMMON AND SCIENTIFIC NAMES' OF SPECIES MENTIONED

Lumber or local name Recognized common name

-^^^ Green ash

White ash _

Basswood; linden Basswood

Beech American beech .

Birch, yellow Yellow birch _ _

Backgum Black túpelo .

Blackgum, swamp Swamp túpelo

Chestnut Chestnut

Cherry____ Black cherry. .

Cot onwood Eastern cottonwood

Lottonwood, swamp Swamp cottonwood

fîb''Î American elm...

&'if Cedar elm

fer ^^' American elm Hackberry Hackberry :::_"::;

Sugarberry

Hickory. Hickory.

Agr.,'AgrAS.'S^'Î95^3*'* °^ ^^''''" ^'"^ Naturalized Trees of the'unUed

Scientific name

Fraximis pennsylvanica.

F. americaria.

Tilia spp.

Fagus grandijolia.

Betula aUeghaniensis.

Nyssa sylvatica.

N. sylvatica t^ar. biflora.

Castanea dentata,.

Prunus serótina..

Populus deltoides.

P. heterophylla.

Ulmus americana.

U. crassijolia.

U. americana.

Celtis occidentalis.

C. laevigata.

Carya spp.

States (Including Alaska)" U.S. Dept.
GRADE DEFECTS IN HARDWOOD TIMBER AND LOGS 39

Lumber or local name Recognized common name Scicntijic name

Honeylocust Honeylocust G/edifsia fnacanfho.s.

Magnolia. Maonolia Ma<jii<ilia spp.

Maple, soft Red maple Acer ruhrum.

Silver maple A. sacch<irinum.

Maple, hard Sugar maple ^4. xacchnrum.

Oak, black Black oak Qtiercus celutina.

Oak, blackjack Blackjack Q. marilundica.

Oak, bur Bur oak Q. macrocarpa.

Oak, cherrybark Cherrybark oak Q. fálcala mr. pagoilaejolia.

Oak, chestnut Chestnut oak Q. 'prim^-

Oak, chinkapin Chinkapin oak Q. muehlenherißi.

Oak, Delta post Delta post oak Q. nlellata var'. mississippieniiv.

Oak, laurel Laurel oak Q. laurifolia.

Oak, northern red Northern red oak Q. nibra.

Oak, Nuttall Nuttall oak Q. ¡^utlalln.

Oak, overcup Overcup oak Q. lyrata.

Oak, pin Pin oak Q. palmtris.

Oak, post Post oak Q. slellata.

Oak, scarlet Scarlet oak Q. coccínea.

Oak, shingle Shingle oak (/ imbiicaria.

Oak, Shumard Shuniard oak ^ Q. shumardii.

Oak, southern red Southern red oak Q. fálcala.

Oak, swamp chestnut or cow Swamp chestnut oak Q. michauxii.

Oak, swamp white Swamp white oak Q. bicolor.

Oak, water Water oak Q. niara.

Oak, white or forked leaf white_ _ White oak (J. alba.

Oak, willow Willow oak Q. phellos.

Pecan, sweet Pecan Carya illinoensis.

Pecan, bitter Water hickory C. aqualica.

Persimmon Persinnnon Diospyros L.

Redgum Sweetgum Liquidambar ntyraciflua.

Sapgum Sweetgum L. styraciflua.

Sycamore American sycamore Pialan «.s occideitlalis.

Tupelo Wat er t úpelo N'y.s.sa aqualica.

Walnut Black walnut Juylans n iyra.

Willow Black willow Salix n iyra.

Yellow-poplar Yellow-poplar Liriodendron tulipifera.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Wasliington. D.C.. 20402 - Pricf 3.5 cents

U.S. GOVERNMENT PRINTING OFFICE ; 1963 O—677-366