Figure 10.~-Evaluation of bumps in hardwood fa

POINT OF
CHANGE

iN LOG
CONTOUR y,

MEDIUM BUMP-H uk

tory lumber logs.

Gooneace RISE -H:L = LESS THAN 1:12

{

LENGTH (L) {

| HIGH - STOP CUTTING AT CHANGE IN CONTOUR

) MEDIUM
1

~ ENTER BUMP 1/8 LENGTH)
ON EACH END

LOW ~ ENTER BUMP 1/4

Te
i

LENGTH ON EACH
END

fe

SURFACE RISE ~ NO DEFECT

>

Figure 11.—Evaluation of seams, frost cracks, splits, etc.,
in hardwood factory lumber logs.

SHALLOW sayy
NO DEFOE Gry

FEAR
CENTER
Re 208D

Aseam, frost crack, split, ete. is not a defect
unless it is deeper than 15 % of log diameter.

No clear cuttings can be taken on a log face

that includes a full-length straight seam or

a spiral seam. However, one straight seam

can be placed on the edge of one face and

ij mored, This fixes the location of all other
lefects.

17

DEEP SEAMS (rece

A deep seam entering a face but not running
full length may be overlaid with a clear cut-
ting for one-third of its length, starting at
the inner end.

When a deep seam is entirely within a log,
clear cuttings can be laid over it from each
end for a distance equal to one-fourth its
full length.


FOREST SERVICE STANDARD
GRADES FOR HARDWOOD
FACTORY-LUMBER LOGS

The factory-himber log class has been di-
vided into three grades. The specifications for
these grades (fig. 5) are closely correlated
with the specifications for standard hardwood
Jumber grades, the grade of the log depending
largely on the proportion of log length that is
obtainable in clear cuttings (table 2).

The major factors that affect the quality of
factory-lumber logs are: (1) position of log in
tree (butt or upper); (2) size of log, especially
diameter; (3) straightness; (4) amount and
distribution of scalable defects; and (5)

‘Table 2.—Minimum length of clear cuttings

by log length and proportion required

Loglentth 56 84 28
and inches

8 we eo" Ba”
9 Te 68" 60"
10 ga 76" 68"
W g 2" a3" 74"
12 or 90" 80"
13 or" 9g" BB
14 iV 8" 10° 6" a4"
Ww 12’ 6" 113" 10° 0"
16 13’ 4" 12'0" 10° 8"

Figure 5.—Forest Service standard grades for hardwood factory
lumber logs.*

1/2

Log grades

Grading Faciors rm Fi Po
Position in tree Barts Butise Buits & uppers
Scaling diameter, inches 13-15") 16-19] 20.) | 11-4 12+
Length without trim, feet 10+ 104+ | 8-9 | 10-11
Required Min. length, feet 7 15 3 3 3 3
clear cuttings* . _
of each of 3 Max. number 2 2 | 2 2 2 2
best faces* _
Min. proportion.
of log length 5/6 5/6 | 5/6 | 2/3 | 3/4] 2/3 | 2/8] 1/2
required in clear . °
cutting | i | |
Maximum For logs wit : |
sweep & crook less than 4 of | of os 50%
allowance end in sound | ae 30% 50%
defects
For logs with :
more than 44 o1 one, Bo
end in sound 10% 20% 35%
| defects
Maximum scaling deduction 40%! BOGE 50%

End defect:

See special instructions {p

ge 18)

«From USDA Forest Service Research Paper FPI-63 (73)
"Ash and basswood butts can be 12 inches if they other ;
«‘Pen-inch logs of all species can be #2 if they otherwise mect requirements for small # V's

“ Aclear cutting is a portion of a face, ext
“(A face is 4 of the surface of the log a:
' Otherwise #1 logs with 41-60% deductior

in be

«Otherwise #2 logs with 51-60% deductions can he # 3.

i

ise meet requirements for small 21's

ding the widih of the facc, that ts free of defects.

led feng thwise,
#2


tion of log defects, straightness, and soundness
of heart (table 1). Many logs that fall into this
class do not meet the requirements for the
factory-lumber class, bui are well suited for ties
and heavy structural timbers. Sound, straight,
small-knotted factory-lumber logs will also
meet these specifications. Examples of typical
structural-class logs are presented in figure 15.

For grading purp it is considered that the
log contains a square timber, the dimensions of
which are governed by the small end. Holes are
allowed if their depth does not exceed 5 inches
from the log surface. Table 3 shows allowable
knot size (one-quarter width of face) for the
largest squared timber obtainable by log diam-
eters; log knot size (one-third log diameter at
point of occurrence) for corresponding log;

maximum sweep allowed per § feet of length;
and the largest timbers obtainable from a given
log, including squared and other commonly
stocked dimension timbers.

Larger knots could he allowed where dimen-
sion timbers other than squares are to be made,
but knot diameter cannot exceed one-quarter
of the width of the face of the tie or timber on
which it occurs. Where it is definite that logs
are to be used for ties, knots up te one-half the
diameter of the log at point of occurrence are
allowable when they are within 12 inches of
either end of the log. This exception cannot be
applied to standing timber,

‘Table 8 will also be helpful in estimating the
products obtainable from construction logs, and
in relating log character to products.

Figure 15 Examples of hardwood construction lumber logs.

A 10-foot log 18 inches in diameter at the small end. The cuttings
on at least two of the four faces are not equal to the minimum re-
quired for factory grade 3. Although it has numerous knots, none
has a knot collar exceeding '4 of the log diameter at the point
where it occurs. The log contains no rot, shake, or splits, and it is
straight.

A 12-foot log, 22 inches in diameter at the small end. The cuttings

on at least. two of the four faces are not equal to the minimurn re-
quired for a factory grade 3. The numerous knots are small and,
although the log is sweepy, the actual sweep does not exceed 14
of the diameter of the small end of the log. There is no rot, shake,

or split.

21


Log Grades in General

OBJECTIVES OF LOG GRADING

\ major objective of log classification is to
arate from woods-run logs those that are
table for the manufacture of a given prod-

or class of products (veneer, standard
ther, ties, etc.) and, for each kind or class
separated, to determine the relative quali-
3 of products obtainable from grades of logs
h common surface characteristics. Other
ectives are to establish basic specifications
log merchantability. to guide manufactur-

processes and methods, to increase the
ciency of sampling for various forestry pur-
ses, and to provide the basis for tree gr:
3ome people judge usefulness of a log
stem by simplicity or ease of application.
is is not a sound approach. Whether log
des are suitable for a given objective
pends not upon how easy they are to use
t upon how well they meet stated perform-
ce standards, Im the task force report pre-
red for the Forest Service Log Grade Com-
ttee (10), the objectives and the applica-
n of standards are discussed in considerable
tail. For example, in the hardwood factory-
nber log grades, the Forest Service stand-
Is requive that the system must:

1. Separate from woods-run logs those that
e logically suited for sawing into standard
ctory lumber,

2. Segregate such logs into high-, medium-,
d low-quality groups (grades) determined
the lumber-grade yield pattern and gross
mber value they will produce when sawed
to lumber in an adequate mill by a sawyer
illed in the production of standard graded
rdwood lumber.

8. Provide a substantial differential in aver-
ce lumber value hetween the several log
ades, and minimize the overlapping of values
individual logs in the different grades (as

when a low-grade log cuts out better than a
log of equal size in a higher grade).

4. Perform on small numbers of logs (say 25
to 50 logs) as well as on larger numbers.

5. Use terms and methods sufficiently objec-
tive so that men with a reasonable amount of
training and experience can apply them in a
practical way to a wide range of activities
(limber appraisal, timher management, log
sale or purchase, production control, or
research).

POOREST LOG CONCEPT

Any system for grading raw material musi
provide a floor: a limit below which the mate-
rial is not acceptable for conversion, Thus, a
poorest log is specifically described even
though it is recognized that: its specifications
inay vary from time to time with changing
economic conditions. If material helow this
arbitrary minimum is utilized, it becomes
merely another group of bole segments,
usually of minor significance, which can be
evaluated separately. When the use does not
include everything down to the poorest log, as
defined, the minimum can be raised to the
next higher standard classification.

A practical definition for a standard mini-
mum hardwood log is: Any piece of a tree
stern 8 inches or more in diameter and 8 feet
or more in length, with sweep not exceeding
one-half the diameter of the small end; with
not more than two-thirds the gross volume in
scalable defect; and with any number of
knots. holes, rotten areas, etc.—provided the
diameter of none exceeds one-half the diame-
ter of the log at point of occurrence. A log is
separated from a bolt by a length specifica-
tion: bole segments 8 feet or more in length
are called logs: those under 8 feet are generally
called bolts, The potentially usable material in
a hardwood tree is illustrated in figure 1.



&. Spiral seams, frost cracks, and splits, ex-

tending inte inner quality zone: stop clear

cutting where defect enters face being

led.

ird peck. Individual pecks are not counted:

length of pecked ai s measured. A pecked

area is one containing four or more pecks

within } square foot.

a. Lightly pecked area (fewer than four
pecks per square foot): disregard.

bh, In grade 1 and 2 logs with four or more
pecks per square foot:
(1) Tf pecks are open, disregard.
(2) If pecks are partially or completely
occluded, the pecked area is a defect.
(Note: age of peck does not matter; test
is whether callus tissue is formed in the
peck-holes.)

c. In grade 3 logs: disregard all pecked
areas.

End Features

1, Definitions

Heart center. Heart center is considered
to be a core in the center of the log with
a radius cqual to one-fifth of diameter
(fig. 12).

. Quality zone. The portion of the log out-

side the heart center (fig. 12).

(1) Inner quality zone—inside half of
quality zone.

(2) Outer quality zone~outside half of
quality zone,

». Affected area. This is defined as the area

in which there are blemishes within 3
inches of each other. The total affected
area, and not the area of the individual
blemishes, is what determines the de-
grading effect.

Figure 12.—Location of end features in hardwood factory lumber logs.

HEART CENTER
R- 20% D

INNER QUALITY
ZONE.
R-15%

OUTER QUALITY
ZONE
R-15% D

QUALITY ZONE
(inner plus outer)
R = 30% D



GENERAL
GRADING PROCEDURES

Scaling

Sealing a log is the first step in grading. Tt
not only gives an estimate of the content (table
4), but also gives some of the data needed to
apply grade spec ions. Sealing should be
done carefully, according to standard practices
that conform to those used in developing the
grading rules. For hardwood sawlogs these are:

Diameter measurement: Average small end,

inside bark.

Length measurement: Longest included full

foot.

Scaling deductions:

1. Interior deductions.—the revised scaling
practice developed by Grosenbaugh (4) at the
Southern Forest Experiment Station works as
follows (rule 5, fig. 18 and Appendix II):

Enclose defect in circle or ellipse (say, 7
inches x 9 inches on a 20-inch log).
Measure short and long axis of circle or
ellipse in inches and add 1 inch to each
measurement (8 inches x 10 inches).

Determine, for each augmented axis, what
percentage it is of log diameter in inches
minus {, and round off to nearest 10 per-
cent (8/19 . 40 percent, 10/19 = 50 per-
cent).

Determine length of defect as percentage
of log length (say, 4 or 25 percent).
Multiply long axis percentage, short axis
percentage, and length percentage to-
gether; the result is the percentage deduc-
tion (40 x 50 x 25 = 5 percent).

(4)

()

2. Other deductions.—Grosenbaugh’s rules
(rules 1-4, fig. 18) cover these. In determining
sweep the number subtracted from actual

Table 4.—International 1 /4-inch log rule*

Diameter
Gnches)

Volume (board fect) according to length, in fect:

400 555
590

35 450 625

* Values as published by HLH. Chapman, extended by formula: V >

section. Taper allowance: \4 inch per 4 feet lineal.

24

TID) x .905 for 4-foot

(0.221%


three or more quarters on
one end, or two or more
quarters on both ends: de-
grade one grade.

(b) In grade 3 logs: disregard.

(4) Stain. This is considered on the
sealing end only; disregard if on the
Jarge end only. The affected area in
this case is the total area involved,
including the heart center. When
stain occurs in several solid areas
that are not joined, the extent is the
sum of the individual areas.

‘Treat as follows:

(a) In grade 1 and 2 logs:

(i) Uf diameter on scaling end
is less than half the scaling
log diameter, disregard.

(ii) If diameter on scaling end
is more, drop one grade.

(6) For grade 3 logs: disregard.

CONSTRUCTION-LOG CLASS
(Ties and Heavy Timbers)

This class has not been divided into grades
(fig. 14). The major factors that aflect the
quality of this class of logs are size and condi-

Figure 14.—Forest Service standard specifications
for hardwood construction logs.*

ition in tree Butt & upper
Min. diameter, small end Sinches +
8 feet —_

Min. length, without trim

Clear cuttings

No requirements.

Sweep allowance, absolute

14 diameter small end for each 8 feet of
length.

|
Single knots

Any number, if no one knot has an aver-
age diameter above the callus in excess
of % of log diameter at point of occur-
rence.

Any number if sum of knot diameters
above the callus does not exceed 1 of
log diameter at point of occurrence,

Sound |
surface |Whorled knots
defects

[Holes

LL H

Any number provided none has a diam-
eter over 14 of log diameter at point of
occurrence, and none extends over 3
inches into included ti r?

Unsound surface defects

und

oo

No requirements.

Same requirements as x sound defects
if they extend into included timber.”
No limit if they do not.

End

defects ‘Unsound

H

None allowed; log must be sound in-
ternally, but will admit 1 shake not to
exceed '4 the scaling diameter and a
longitudinal split not extending over 5
inches into the contained timber.

« These specifications are minimam for the class. If, from a group of logs, factory logs are
selected first, thus leaving only non-factory logs fram which to select construction logs,

then the qual

subdivide the class into grades,

range of the construction logs d
ade. If selection for construction legs is given first priority, then it may be

0 selected is limited, and the class may be

"Inclined timber is always square, and dimension is judged from small end,

20


Figure 9._Examples of hardwood factory grade 3 logs.

Position

Size...

Straightnes:

Soundness .

Cuttings .................One-half of its grading-face length is clear in
two sections, each 2 feet long

Upper log
Length 12’, diameter 14” at small end

Straight,
.15 percent rot deduction (less than 50 percent.
maximurn permitted)

Size .....
Straightness
Soundness

Cuttings More than 4 of its grading-face length is clear in
two sections, 4 and 3 feet long
Comments ................ Interior rot outside the vot zone limits cuttings
3°

a 2

Upper log

Position
Length 14’, diameter 22” at small end

Size...

Straightness . 12 percent deduction for 6” x 3’ of crook on both
ends of log

Soundness ................15 percent rot deduction (crook and rot less than
50 percent maximum deduction)

Cuttings ... wu. More than % of its grading-face length is clear

in three sections, 3, 3, and 2 feet long

Upper log

Length 16’, diameter 22” at small end

traight

Sound

More than % of its grading-face length is clear
in two sections, 5 and 4 feet long

15

Position
Size...
Straightness
Soundness

Cuttings



them all merely suh-grade logs: or he sorts out
the logs that will make the next most valuable
class, construction lumber. Any further resi-
due then falls into the local-use class—pro-
vided, of course, that they meet the minimum
specifications.

This method of grading is a one way street.
for logs not suitable for the first classification
may be suitable for a lower class.

OTHER PRODUCTS

So far, we have heen concerned primarily
with veneer, lumber. and timbers, and it may
seem that inadequate attention has been given
to other products such as cooperage, dimen-
sion stock, handle stock and specialties. How-
ever, multi-product logging has already recog-
nized the need for sorting out the numerous
products, inclucing pulp. These items do
assume considerable importance locally, and
account for about 25 percent of total hard-
wood utilization. Specialty product specifica-
tions are related closely to those for factory
lumber because relatively short, clear pieces of
practically defect-free wood are required. Lim-
ited studies of specialty products have shown
that log quality for specialty products can be
gaged closely by the hardwood factory-lumber
log grading system or modifications thereof.

GRADE DEFECTS
AND SCALABLE DEFECTS

The Society of American Foresters in its
Forestry Terminology defines the term defect
very broadly as “any irregularity or imperfec-
tion in a tree, log, piece product, or Jumber
that reduces the volume of sound wood or
Jowers its durability, strength, or utility
values.”

Defects fall into two main categories: (1)
those that reduce the volume of sound wood
or lower its durability; and (2) those that
lower its strength, take away from its appear-
ance, or otherwise limit its utility. The first
are scalable defects (rot, shake, etc.). The
second are grading defects (knots, stain, etc.).

The term defective timber popularly con-

notes rotten or over-mature trees, but such
trees may contain much usable material. The
amount of sealable defect, together with size
limitations, is often the main criterion of mer-
chantability of logs or trees. Actually, logs

from which unusable material (scalable
defect) will be removed in manufacture are
not on rily defective in grading terms, for

there may be no grade defects in the remain-
ing usable wood.

On the other hand, perfectly sound trees
(without scalable defect) may be worthless
because of grade defects that cannot he elimi-

ated in manufacture. The distinction between
scalable defects and grade defects is not always
clear-cut. Small volumes of scalable defect may
be left in the product, affecting strength or
utility or lowering product grade by detracting
its appearance; they then become grade de-
fects.

Usage gives the term “grade defect” to
abnormalities or irregularities on the log sur-
face 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 product grade
defects. Further discussion of this can be
found in U. S. Department of Agriculture
Handbook No. 244, Grade Defects in Hard-
wood Timber and Logs (7).

The importance of use class in grading
becomes apparent when log grade defects are
considered. In one use class a certain irregu-
larity or imperfection in the wood is a product.
grade defect, so the defect indicator on the log
surface is a log grade defect. In another use
class, the same irregularity or imperfection
does not degrade the product, so the defect
indicator on the log surface is not a log grade
defect. An example of this is a 14-inch sound
knot. In factory lumber this is a product grade
defect; in construction logs it is not (table 1).


Table 6.—Scaling diameter: defect length factors

qealng Percent of log length in cull section
inches 10 420. «+30 +~«40~«50~SOG—=~«TS*«DS*C‘<«‘“SC
8 12 24 3.5 47 5g Ti 8.2 94 106 118
9 ® 18 27 36 45 54 63 72 81 90
10 7 14 21 98 36 43 50 59 6A 74
u 6 1) 17 28 29 84 40 46 52 58
2 5 10 14 19 24 29 33 88 43 48
B 4 8 12 16 280 24 28 32 36 40
4 3 7 0 4 17 20 24 27 B1 384
15 3 6 9 2 TH 8 21 24 26 29
16 3 5 8 10 18 15 18 20 28 26
VW 3 A 7 9 11 4 1.6 18 2.3
18 2 4 6 8 10 12 4 15 20
19 2 4 5 7 "9 41 12 V4 18
20 2 8 5 6 8 to 11 13 16
21 2 8 4 6 47 9 0 12 14
22 ee ne a 2) 13
28 1 2 %4 5 6 OT) ROO 12
oy 1 2 3 4 5 6 »8 39 VW
25 1 2 38 4 5 6 7 & 10

Note: Do not take off an inch in measuring diameter.

Table 7.—Interior defect cross-section factors

Short Lon:
axis,
inches 2 3 4 5 6 7 Wu 12 «#13
2 2 2 3 3 4 4 6 7 7
3 _ 3 3 4 5 5 8 9 10
4 -— = 4 5 6 7 1 WW 12
5 - - = 6 7 8 12 4 15
6 —- -—- — 8 w 15 16 (17
7 —- -—- | -—-- W718 19
8 -— —- eee 19 20 22
9 eee 21 23d
10 ~ -— ee 93°35 7
i — —- - - —-—- —~ — 8 7 w
12 eae eae 8D
13 _ —-— - - -- - - — — 84
14 Ke ee eee ee eK
15 —~ ee ee ee ee ee
16 -_ = —-— Fr rr
17 SF ra
18 - SF OT OT

Note: Do not add a collar allowance in measuring axes.

‘STU.S. GOVERNMENT PRINTING OFFICE: 1995/650-136/20012 31


Hardwood Tree Grades
for Factory Lumber

The U.S. Forest Service Hardwood Tree
Grades for Factory Lumber were developed
for use on standing sawtimber (4a). The tree
grade specifications are accompanied by dry
lumber grade yields for 11 species: yellow
birch, paper birch, red maple, sugar maple,
yellow-poplar, black cherry, basswood, north-
ern red oak, black oak, white oak, and chest-
nut oak. Lumber grade yields are also avail-
able for graded aspen trees (4b).

By applying these tree grades to a stand of
timber, you can divide the trees into three
groups, each with its own set of lumber grade
vields. You ean then predict the volume and
value of lumber that can he sawed from the
graded trees.

A tree's grade is related to the grade of the
butt log. The sections of this guide that per-
tain to evaluating the surface features of fac-
tory logs should be consulted when grading
trees,

Selected References

Engineering Association.
UAL FOR RAILWAY ENGL
s. Chicago, Il. 42 p.

1. American Railw:
i970, AREA,
inG, Chap,
Carpenter, R. D.

G67. MAJOR DEFECTS IN SOUTHERN HARDWOOD

LOS AND BOLTS. South, Lumberman 214

2668): 18.

3. Flick, Frances &.,

Sigler.

1961, GRADING OF LOGS AND TREES FOR QUALITY:
BIBLIOGRAPHIES COMPILED FOR THE Forest -
vick Log Grating Commirrer. USDA For. $
Washington, D.C. 50 p.

4. Grosenbaugh, L. R.

1952, SHORTCUTS FOR CRUISERS AND SCATERS.

ISDA For. Serv. South, For. Exp. Stn. Ovcas.
Pap. 126. 24 p,

4A. Lanks, Leland F.

1976, HARDWOOD TREE GRADES FOR PACTORY LUM-

ner. USDA For. Serv. Pap, NE-333. 81 p.

Hanks, Leland F., and Robert 1. Brisbin.

1978. LUMBER GRADE YIELDS FOR GRADED

LOGS AND TREES. USDA For. Serv. Res.

NE-423. 13 p.

5. Harrar, E. S.. and R. A. Campbell.

1966. THE MAJOR DEFECTS IN SOUTHERN HARD-

p

Nellie G. Larson, and Marcia

4E

ASPEN
Pap

WOOD VENEER LOGS AND BOLTS. USDA For. Serv
Res, Pap, SE-19. 23 p.

6. Henley, J. W.
1961, OVERRUN ESTIMATES OF THE ScRIRNER

Decimal C LOG RULE AND THE INTERNATIONAL
14INCH LOG RULE For HarDWOOD Los, USDA

10. Newport,

11, Putnam,

For, Serv, For. Prod. Lab. Rep. 2214. 4 p. + 68
tables

7. Lockard,
Carpenter.
63. Grape DAPECTS 1, TARDWOOD, TIMER, AND

eR, FA, Putnam, and R. D.

US. Dep. Agric., Agric. Handb, 244. 89 p.
8 Lockard, C. BR. J. iN “Putnam, and R. D. Car-
penter.
1950. LOG DEFECTS IN SOUTHERN

US. Dep, Anric, Agric. Handb. 4.

9 National Hardwood Lumber Asso
1971. ROLES FOR THE MEASUREMENT AND IN,
SPECTION OF HARDWOOD ESS LUMBER.
al

azo, IU. 116 p.
Carl A, ©. R. Lockard, and C. L.

Vaughan

59. LOG AND TREE GRADING AS A MEANS OF

; quatity. Natl Log Grade Comm.,
USDA For, Serv, Washington, D.C, 31 p.

GM. Furnival, and J. S

McKnight.
1960, MaNAcrMe:
ERN Harpwoons. U,
181. 102 p.

U.S. Forest Service.

1964, CHANGES IN MILL, RUN ITARDWOOD SAWLOG
LUMBER GI WHEN VENEER LOGS ARE
witHprawN, USDA For. Serv. Res. Pap. FPL-
13, 134 p.

AND INVENTORY OF
Dep. Agtic., Agri

SOUTH:
Handh,

18. US. Forest Service.

1966, HARDWOOD LOG GRADES FOR STANDARD LUM-
ner. USDA For. Serv. Res. Pap. FPL-63. 52 p.

27


HARDWOOD LOG USE CLASSES

The many factors that influence log quality
an be isolated and their effect gaged only if
se is taken into consideration. Not all hard-
ood logs that exceed the minimum speci
ions are equally suilable for all
yen though the quality requirement
imilar. However, four log-
nough to cover current hardwood utilization
ractices. They are as follows:

1. Veneer Class.—This class includes the
ery high value logs as well as some relatively
yw value logs. Many logs that qualify for fac-
ory-lumber grades 1, 2, and 3 can also he uti-
zed as veneer logs.

Interim specifications for northern hard-
rood veneer logs (birch, heech, maple, and
herry) were approved by the Chief of the
‘orest Service in March 1964 for use in timber
ppraisals in Region 9 and that part of Region

that is in the southern Appalachian Moun-
ains.

2. Factory Class.-This type of log is
dapted to the production of boards that later
an be remanufactured so as to remove all
efects and obtain the best yields of clear face
nd sound cuttings.

The grade of lumber cut from such logs is
etermined by specifications of the National
lardwood Lumber Association grading rules
w standard lumber (fig. 2) (9). These grades
vecify the minimum yield of defect-free mate-
al from boards in each grade. High-grade
yards are those that will yield high percen-
of clear face cuttings in relatively large
Low-grade boards are those that yield
nall percentages of clear face and sound cut-
ngs.

Re

3. Construction Class.—This class includes
gs suitable for sawing into ties, timbers, and
her items to be used in one piece for struc-
wal purposes. Grade specifications are con-
ined in the construction-lumber section of
te National Hardwood Lumber Association
les; the tie specifications of the American
ailway Association (1); and the standard
vecifications for structural wood joists and
anks, beams and stringers, and posts and
mbers of the American Society for Testing
laterials,

In general, these specifications are desig
to insure the strength of the piece. In the
usual run of logs suitable for this use, position
and condition of the heart center are espe-
cially important. Knots and other defects that
would impair the strength of the product are
limited to si that hold the impairment.
within acceptable limits.

Although factory-lumber grades allow more
defects in the lower grades, construction
lumber specifications prohibit weakening
imperfections equally in all grades. This
results in log requirements different from
those for factory-lumber use. For example, a
factory log with a rotten, shaky interior, and
having large but widely spaced surface defects
may produce enough high-grade boards to
yield a high average quality. Yet such a log
would be practically worthless as a construc-
tion log (see figure 8, fourth illustration).

4, Local-use Class.—In general, local-use logs
are those that are suitable for products not
usually covered by standard specifications.
High strength, great durability, or fine appear-
ance are not required for the following types
of products: crating, pallet parts, mine tim-
bers, industrial blocking, secondary farm
buildings, etc. Whereas the other three classes
are usually sold over a wide area and through
a variety of marketing channels, local-use
materials are generally sold directly to the
user by the producer. This often makes local-
use logs rather profitable.

Within the veneer, construction, and local
use classes we may need further separation by
grades. The grade specifications are designed
to separate logs into value groups based on
product requirements. There is no implied
price relationship between any grade in one
class and any grade in another class. There
may be no basic price distinction between
classes. The value of the products in the var-
ious classes, and of the grades from which
they can be made, depend upon the processing
equipment and operating methods of the oper-
ator. For example, a mill that converts con-
struction-class logs has an entirely different
value basis from a mill processing factory-lum-
ber logs. The local-use class usually has the
least value, but this does not mean that logs in
this class are unprofitable.


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rade 1 logs will generally range [rom 65 per-
ent upward: for factory grade 2 logs, from 40
» 64 percent; and for factory grade 3 logs,
rom 13 te 39 percent. Detailed grade-yield
vformation is available in U.S. Forest Service
esearch Paper FPL-63 (13).

SPECIAL INSTRUCTIONS
FOR FACTORY Locs'

iueface Features

Evaluation of defects.--A surface abnormal-
ty, if determined to extend into the log for a
jepth more than 15 percent of the diameter
ut the point of occurrence, is a log grade defect.
Dtherwise, it should be disregarded. All defect
indicators judged to indicate log grade detects
are counted as equal, with the following exeep-
tions in factory logs only:

1. Epicormic branches:

a. Large (limbs more than % inch diameter
at origin or bark surface): full defect on
logs of all sizes, grades, and species.

b. Small (limbs 4% inch diameter or less) :
(1) Hard hardwoods? (except black

cherry, where they are not counted
as defects): All grades: On logs less
than 14 inches: full defect. On logs
14 inches and more: one-half defect;
i.e, skip every other one.

(2) Soft hardwoods: Grades 1 and 2:
full defect on logs less than 14
inches; one-half defect. on logs more
than 14 inches. Grade 3: no defect.

2. Grab holes and grub-caused overgrowths:
a. Progressive on face.

(1) On logs 8-15 inches: each is a full
detect.

(2) On logs 16-19 inches: disregard
every sixth one.

(3) On logs 20-23 inches: disregard
every fifth one.

(4) On logs 24-27 inches: disregard
every fourth one.

don USDA Agricultural Handbook #4 (8).
“Includes such species as sugae maple. beech, vel-
tow, hirgh. sycamore, hackberry, all oaks and ashes,
and hi

“Includes such species ag soft maples, basswood,
vellow-poplar, yam, magnolia, willow, cottonwood,
and elm.

16

elm, birch,
cow, and swamp chestnut)

(5) On logs 28 inches or more: disregard
every third one.

ve aligned across face.

va or more of these defects
are for ina hand not more than
6 inches wide across the width of
the face they may be considered as
one.

b, Non-progy
(1) When ¢

3. Bamps: High and medium bumps must be

idered on all logs, although in some

ss! low humps can sometimes be disre-

garded. Measurement of clear cuttings (fig.

10) is affected as follows:

a. High bump (length less than three times
height: example—6 inches long and 4
inches high): Stop clear cutting at.
change in contour. Do not enter bump
with clear cuttings.

b. Medium bump (length three to six times
height: example—12 inches long and 2
to 4 inches high): Let clear cutting enter
bump one-eighth of the length on each
end.

c. Low bump (length 6 to 12 times height:
example--12 inches long and 1 to 2 inches
high): Let clear cutting enter bump one-
fourth of the length on each end.

d. Surface rise (length more than 12 times
height): disregard.

. Straight seams, frost cracks, splits (fig. 11),

extending into inner quality zone.

a. Straight seams extending all or part of
the length of the log that can be consid-
ered as a line dividing two grading faces
can be disregarded.

. Straight seams not confinable to lines di-
viding grading faces.

(1) When full length of log: a full de-
fect.

(2) When extending from one end of log
towards middle: Include one-third
of the seam length on interior end
in the clear cutting.

(3) When completely in log: extend cut-
tings one-fourth of seam length from
each end.

ach species as soft maple, tupelo, soft
ashes, magnolias, and white oaks (white,



Figure 3.—Range of product values for major use class

Estimated range of gross value of products from hardwood logs | Estimated
by quality groups within use classes (in dollars per M board feet) percentage
coe — ~ ; of total log
50100 150-200-250 300350400450 production
+ non
1S 10%
}
° Factory lumber | |
) 55%
High quality
|
Medium quality |
Low quality H
|
% | Construction lumber 20%
| | |
|
=e
Local use lumber 15%
sea ic
Note: He

Use

High-Quality : 7
Class LORS ass

Vencer logs 1B.

Bactory bumiber

Construction Jumber 2
Loeal Use lumber 95. 110

are log values; all others

9-110

‘alues for veneor

ave lumber values.

6


Relationship of log diameter to maximum timber sizes

Table 3- ter tom
and allowable knot size, in inches

Average diameter of Largest timber obtainable (rough, gr
Lange inmost knot allowed — Maximum oe ne trough -
dibs fon fog surface sweep or
sinall o> rook per - com ; / ;
end Largest & foot To Common dimension
Inches) — squared fabsolute! nearest nearest

timber 14 inch inch

2

2-4

212

2-3/4

3

B14

31/2

3-3/4 a -

4 &xtd 10x12

4/4 8x15 9xi4

412 12xid —

4-3/4 x16

5

Sa1/2 14x16 -

6 16x18 _

6-1/2 16x20 _
4a 7 —

add “1/2 =
fie.
“Tass 1 eross tie, “Cl
“hy 2 evermatie
€ is herenss ti rc

Fatinch variation allowed for mismanufacture: 15x 15 ar 16 x 16,

Figure 16.—Suggested specifications for hardwood
local-use logs.

os Butt and upper
Min. diameter, small end 8 inches +-
Min. length, without trim 8 feet +

» allowance, absolute 4 diameter of small end

scale deduction allowed %
Clear cuttings No requirements
Sound or unsound Only requirement is that diam-
surface defect limitations eter of knots, holes, rot, ete.

shall not exceed Y% diameter of

ne log at point of occurrence.
Sound end defects No requirements _

22,


a guide to
HARDWOOD
LOG GRADING

(Revised)

by Everette BD. Rast
David L. Sonderman
Gienn EL. Gammon

U.S.D.A, FOREST SERVICE GENERAL TECHNICAL REPORT NE-!
1973 .

Forest Service, U.S. Department of Agriculture
Northeastern Forest Experiment Station
370 Reed Road, Broomail, PA. 19008


Definition and Application of Specifications
fer Hardwood Log Classes and Grades

HARDWOOD VENEER-LOG CLASS

The term veneer includes not only fancy or
face veneer but also veneer suitable for the
backs and cores of plywood panels and veneer
for containers.

It has been commonly assumed that veneer
logs must be of exceptionally high quality and
that only a small proportion of factory grade
sawlogs will qualify as veneer logs. Compari-
son of the Forest Service factory-lumber log
grade specifications with the veneer-log speci-
fications of the Northern Hardwood and Pine
Association indicates that this assumption is
incorrect, U.S. Forest Products Laboratory
Research Paper FPL-13, Changes in Mill Run
Hardwood Sawlog Lumber Grade Yields
When Veneer Logs Are Withdrawn (12),
shows that a varying proportion of both grade
1 and grade 2 factory lumber logs will qualify
as veneer logs. The material for hacks and
cores of plywood panels and veneer for con-
tainers definitely allows the small sound
defects generally permitted in the cuttings of
the lower common grades of factory lumber.
Logs suitable for these lower classes of veneer
are often found among grade 3 factory-lumber
logs.

At present there is no standard system for
grading veneer logs that is based on research.
However, there are numerous local grade spec-
ifications, such as those published by the
Northern Hardwood and Pine Manufacturers’
Association and the American Walnut Manu-
facturers’ Association. Because they are gener-
ally based on limited information about the
factors influencing veneer-log quality, these
systems could be improved. Studies made hy
the Forest Products Laboratory have provided
the vencer grades necessary to develop such
specifications for logs. These are contained in

Forest Products Laboratory Research Paper
FPL-9, Recommended Veneer Grades for the
Development of Hardwood Veneer Log Grades
and Forest Products Laboratory Note 025,
Using the FPL Hardwood Veneer Grades,

Late in 1963, the leader of the Hardwood
Log Grade Project was author by the
Washington Office, Division of Timber Man-
agement, to develop veneer-log specifications
to be used in Forest Service timber sale
appraisals. In cooperation with the regions
involved, the project leader developed a set of
interim specifications for northern hardwood
veneer logs (fig. 4), recommended mainly for
the northern hardwood species: beech, birch,
maple, ash, and cherry. These were approved
hy the Chief of the Forest Service in March
1964 for use in timber appraisals in Region 9
and that part of Region 8 that is in the south-
ern Appalachian Mountains.

These specifications are based on limited
information about the factors that influence
veneer-log quality, but they are definite and
explicit enough to be applied directly. They
should not be considered final, but merely a
bridge between the present and the time when
additional studies supply the data for develop-
ing standard veneer-log grades and accompa-
nying veneer-grade yield tables.

The interim specifications clarify specific
grading factors, and are quite similar to the
Northern Hardwood and Pine Association
specifications. Adventitious bud clusters and
small branches (less than 44 inch) are disre-
garded because they will normally disappear

in “rounding up” the log.

The specifications define use classes, They
provide a sound basis for separating poten-
tially fancy or face veneer quality material
from factory-lumber logs, and they are applic-
able to both cut logs and standing trees.



Table 1.—Classification of log surface abnormalities

—_ ‘Use
Logs

Pactory Construction Loca
Logs Lo

Abnormal

Tog surfac

Tulges:
Butt Defect No defect
Stem Defect No defect,
Bumps:
High (s) (3)
Medium (3) (3)
Low (3) (3)
Burl Defect (3)
Butt scar (3) No defect
Rutt swell 3) (3)
Canker Defect No defect
efect Defect No defect
(2) No defect. No defect
Epicormic branches (2) No defect. No defect.
Flang No defect. No defect No defect
8 (3) (3) No defect
Defect Defoet No defect
Gum lesions (3) No defect No defect
Holes
Large Defect (3) (3)
Medium:
Bark se No defect No defect. No defect
Bark se Defect No defect No defect.
Birds, light No defect. No defect No defect.
Birds, heavy Defect No defect No defect
Grub (2) No defect No defect.
Increment borer Defect No defect No defect
Tap Defect No defect No defect,
Small (3) No defect No defect
Log knots:
Sound Defect (3) (3)
Unsound Defect (3) 3)
Limbs Detect (3) (3)
Overgrowths:
Knots & bark pockets De (By No defect
Defect No defect No defect.
Defect No defect No defect
Defect No defect. No defect.
No defect No defect No defect
(2) (3) No defect
(3). (3) No defect
No defect No defect No defect
Wounds:
New No defect No defect No defect
Old (3) (3) No defect
Logend
Bird peck (2) No defect No defect
Bark pocket (crotch) Defect Defect No defect
Double pith No defect Defect No defect
Grease spots (2) No defect No defect
Grab channels (2) (3) No defect
Gum spots (2) No defect No defect.
Loose heart ab Defect No defect
(2) Defect. No defect
(2) No defect
(2) No defect
k (3) No defect
Spider heart (2) No defect
Stain. (2) No defect No defect
Worm holes:
Pin, flag & shot Defect No dofect No defect

(1) Defeot if not confined to heart conter & inner quality zone.

(2) Refer to Special Instructions far Factory Logs Qiaye 16)

13) Refer to Grade Defects in Hardwood ‘Timber and Lo;
pars

gt. Handbk. No.


Appendix Ti

TABLES FOR MAKING
INTERIOR SCALE DEDUCTIONS

These two working tables of factors for de-
termining scale deduction are based on Gro-
senbaugh’s Rule 5.

Table 6.~Factors given in this table express
the relation of scaling diameter minus 1 (in
inches, average d of small end) and length
of scaling defect section (as estimated to the
nearest 10 percent of log length). Use actual
diameter, do not take off an inch.

Table 7.—This table shows factors that eval-
uate the cro ction of the defect area. Actual
long and skort dimensions in inches are used;
do not add a collar allowance in measuring.

To find scale deduction:

1. In Table 6, find factor for log scaling diam-
eter (inches) and length of scaling defect
section (percent of log length), ie., for an
18-inch log with a scaling defect section 30
percent of its length the factor is 0.6.

In Table 7, find factor for short and long
dimension of defect cross section (i.e, 5
inches x 7 inches =: factor 8).

3. Multiply the two factors to get scale deduc-
tion in percent of log scale: 8 x 0.6 = 48
percent. Round to nearest percent = 5 per-
cent.

If this procedure seems cumbersome, con-
sider the sequence. Log length, scaling diam-
eter, and scaling-defect section length can be
determined in one operation; cross-section di-
mensions in another. As the first two (length
and diameter) are recorded, the table 6 factor
for defect length can be observed and kept in
mind. Then, after the cross section is measured,
the appropriate factor can be located in table 7
and the two factors can be multiplied mentally.

For logs over 25 inches in scaling diameter,
use Grosenbaugh’s Rule 5, page 25.

Where cull area goes completely through the
log, use the average of dimensions measured on
both ends,

Where defect cross-section can be contained
ina rectangle instead of an oval, multiply chart
values by 5/4.

30


Appendix Z

HOW TO USE LOG-GRADE INFORMATION
TO ESTABLISH LOG VALUES

Factory-Lumber Loge

Log grades accompanied by lumber grade
yields provide the information needed for value
determination. U.S. Forest Service Research
Paper FPL-63 presents lumber grade yield in-
formation by log grade and diameter for several
hardwood species. Log overruns and lumber
thickness distributions are also covered in the
report. One method of obtaining log value is
outlined below.

I. To determine value per Mbf.

a. For each log grade-diameter class ap-
ply the percent yields to the lumber
tally as shown.

. Apportion the resulting lumber

grade volumes into the various thick-

ness classes using either the tabular

thickness distribution or one better

suited to the situation.

Apply current lumber prices, pub-

lished or local, to these lumber grade

thickness volumes, and obtain fotal

lumber value.

Divide this value by total lumber

tally; the result is value per Mbf

for the log grade-diameter class in

question.

To determine log volume.

a. Obtain net scale of a log.

bh. Estimate lumber volume hy applying
appropriate overrun to net log scale.

To determine log value.

a. Multiply the estimated lumber vol-
ume by the value per Mbf and divide
the product by 1,000.

G

Ti.

TL.

29

This method of value determination predicts
the value of lumber that can be sawed from a
log with good sawing practice in a well main-
tained mill. Differences between actual and
predicted values will be quite high for single
logs, hut will decrease as the number of logs
increases. We suggest that 20 logs is the mini-
mum number for which consistent results
should be expected.

The following sources of lumber price infor-
mation should be consulted:

NATIONAL HARDWOOD MAGAZINE, 2029 Pea-
bady Ave., Memphis, Tenn. Prices of southern
Applachian and northern hardwoods, f.0.b.
Chicago, are published each month.

Harpwoop MARKET REPORT, P. O. Box 4042,
28 N. Cleveland, Memphis, Tenn. Prices are
published weekly for southern hardwoods, f.0.b,
mills in Texas and Louisiana; for Appalachian
hardwoods, £.0.b. mills in the Johnson City,
Tenn., area; and for northern hardwoods, f.0.b.
mills in the Wausau, Wis., area.

COMMERCIAL BULLETIN, Curtis Guild & Co.,
88 Broad St.. Boston, Mass. New England hard-
wood and softwood prices are published weekly.

For construction and lceal-use logs, no
graded product information is available. Values
must be developed from individual mill experi-
ence. The National Hardwood Lumber Asso-
ciation’s Rules for the Measurement and In-
spection of Hardwood and Cypress Lumber
should he consulted for information about other
products.


Figure 2.—Basic grade specifications for hardwood lumber.*

Minimum Specifications
Yieldof | ;
Grade Length") width | fughtumber | Size | Cuttings!
(ieet) | (inches) cuttings cuttings (number)
J a
Firsts & 8 6 \ Lto4
seconds or
BU x7
Selects 6 4 Better face is seconds; reverse side of
cutting is sound, or reverse side of piece
is 1 Common.
1 Common 4 3 6635 4’ x2’ 1to5
or
9" x 3"
2 Common 4 3 50 87x Lto7
Sound Full log yield of 1 Common and better, with worm holes,
wormy knots, ete. not over 34 inch; stain admitted into cuttings.
3A Common 4 3 331% 37x 2" No limit
3B Common 4 3 25° 115 & con-
taining not | No limit
less than
L 6 sq.in,

* The basic grade specifications for hardwood lumber were adapted from the rule book of
the National Hardwood Lumber Association (Chicago, Jan. 1971-Jan, 1975) pp. 17-23.
” Percentage of short lengths is limited by grades: Tor example in First only 12 per-

cent can be 8 feet to 9 feet; in 2C, 10 percent can be 4 feet to 5 feet,

A. Clear face cuttin,
mitted) and the rever

defects:
stain

provided it will dress out.

‘ound cuttings: A cutting {ree from rot, pith,
sidered, It will admit sound knots, bird peeks, stai

‘A cutting having one clear face (ordinary season checks ad-
‘ide sound as defined in “sound cuttings,”
cutting shall be on the poor side of the board except when other

The clear face of the
ise specified. Admissible

ordinary season checks, unlimited sapwood, mineral streaks and spots, burls, and

ke, and wane, Texture is not con-
. Streaks or their equivalent, season

checks not materially impairing the strength of the cutting. pin, shot, and spot worm
ta

holes. Other holes 4” or

average diameter in each cutting of less than 12 uni

and on one side only of a cutting.

larger are admitted but shall he limited as follor

One 4” in

is; two 14" to each 12 units

"ar one 1,"

Number varies with surface measure of piece; for example. in 1C with surface measure
of 5 feet to 7 feet, two cuttings are allowed; in 1C with surface measure of 11 feet to 13 feet.

four cuttings are allowed.

° On basis of sound cuttings; lumber is suitable for low-grade crating and dunnage.

The comparative values, as illustrated in
figure 3, provide the log grader with the basic
information for choosing the best possible
grading system that reflects the business situa-
tion for which grading is to be the control.
The values for veneer are log values, whereas
those of the other three classes are lumber
values, because the prices of piece veneer
would be unrealistic in relation to lumber
prices.

For example, at a standard lumber mill first
grading choice is the factory-lumber class.
However, at many lumber mills the veneer
class logs will be withdrawn first for shipment
to a hardwood veneer and plywood plant.
After the grader has selected the logs that
meet the specifications for factory grades 1, 2,
and 3, (F1, F2, F3) he will, in all probability,
be left with a residue of lower quality logs.
Either he does not grade these, considering


2. Evaluation

a.

All abnormalities, regardless of type, can
be disregarded in grading when they are
confined to the 1eart center. However.
they may cause s-ale deductions.

». When an abnormality is not confined to

the heart center, divide the log end into

quarters conforming to the grading faces

and evaluate as follows:

(1) Rot, heart check and ring shake (fig.
13). If these enter the quality zone
in any quarter and are:

(a) Confined entirely within the
inner or outer quality zone,
make scale deductions as usual,
but disregard as a log defect.

(b) In both inner and outer quality
zones, make scale deductions as
usual but consider as a defect in
the quarter and face involved,
as follows:

(i) If it extends full length of
log, no clear cutting can
be taken,

Gi) If it extends only partially
through the log, allow cut-
tings to be measured back
toward the log end one-
third the length of the af-
fected area from the point.
where it is estimated that
the rot or shake tapers out.

(2) Spider heart. Defect if not confined

(3

)

to heart center.

Spot worm holes, shot worm holes,
pin worm holes, bird peck, bark
pockets, grub holes, gum spots,
grease spots. When enough of these
are found to constitute an affected
area in the quality zone and the
radial measurement of this affected
area is:

(a) In grade 1 and 2 logs:

(i) Less than half the radial
width of quality zone: dis-
regard.

Gi) Greater than half the ra-
dius of the quality zone in

Figure 18.—Evaluation of rot and shake in hardwood factory lumber logs.

Rot is defect in all 4 quadrants

19

Rot no defect in quadrant 1 or 2
Shake no defect in quadrant 3
Shake is a defect in quadrant 4


Figure 18.—Methads of determining sealing deduction.

(Examples based on a 16-foal log with 20-inch scaling diameter)

Defies section jane ty

Pewent deduction

i

Defect section (rule 2)
(8); By

Percent ceiaetion (oa) (yy) A

Sweep (rule

Porent deductinn

Crook (rule 4)

W)/4) pipe
B) (gp) eave

Porcent deduction (

is

Interior defect (rae 5)

(8) 40), 4
Hye We
In pnetice ath elipse sis eam be elivided yy (200)
find ronal ter sproncet tenth faite

0

Pervent deduction ~ BAB

han &
Thins Ee

Band (41 (3

Prom: Grosenbaugh. LR. SHORTCUTS FOR eRENSENS AND ScaLIME, USDA Faves, Sere, South, Forest
Fxp. Sta., Orvas. Papier 195, 1952,

25


The Hardwood
Timber Resource

F THE 2 trillion board feet of merchant-
able timber standing on forest lands of
the United States, about one-fifth—400 billion
board feet—is hardwood. One hundred fifteen
commercial species produce sawed products;
74 of these same species also produce veneer.
These commercial hardwood species grow
on half of the nearly 483 million acres of com-
mercial forest land in the country and they
produce one-fourth of all the lumber cut. The
annual harvest of hardwood trees for lumber
and other wood products amounts to about
12.3 billion board feet.

Fabricating this raw material into finished
consumer goods is a complex business. Hard-
woods vary greatly in their intrinsic qualities,
both within and between species. Some, like
yellow birch, cherry, persimmon, and walnut,
have highly desirable qualities that put them
almost. in the class of precious woods. Others,
like beech, boxelder, and scarlet oak, have
qualities that make them much less desirable,
so that there is usually less demand for them.
The wide distribution and variety of species,
together with these great variations in attri-
butes in and between species and the intricacies
of utilization, create both technical and eco-
nomic problems in evaluating a species’ utility.


defects in the side the heart
center. Heart center is used in a restricted
sense; it is a cylinder in the center of the log
with a radius equal to one-fifth of the scaling
diameter,

The Forest Service Standard Grades for
Hardwood Factory Lamber Logs call for grad-
ing the three best. faces. After taking into
account the size and soundness of the log, the
gvader visually squares the log full length into
four faces so oriented as to give the largest
number of good faces. Each face is evaluated
the same way a board would be evaluated,
with the exception that rip and sound cuttings
are not allowed; all cuttings must be clear and
full width of face. The poorest face of the log
is eliminated. The grade of the log is then
determined by the poorest of the three
remaining grading faces (fig. 6). In practice it
is possible for a trained grader to pick out the
controlling or grading face by a quick inspec-
tion only, and make the necessary measure:
ments on this face.

The major problem in grading factor
ber logs is to locate clear cuttings
requires the proper evaluation of
cators of defects. Branch stub

This
surface indi-
and knot over-
growths are clearly evident, so they present. no
problem. But the grader usually needs some
training and experience to detect and evaluate

accurately other less obvious indicators.
Once the faces have heen graded, the log
ends must be

mined for grade defect indi-
eators (hat may not show on the log surface.
These are provided for by special instructions
for evaluating end defects (page 18) and by
the general restriction on the percentage of
sealing deduction allowed in each grade. Mini-
mum diameter, minimum length, maximum
allowable sweep, and position of the log in the
tree are also important grading factors. Exam-
ples of the three factory-lumber log grades are
shown in figures 7, 8, and 9.

Lumber grade yields will vary by species
and diameter within log grades. The yield of
No. 1 Common and Better lumber for factory

Figure 6.—Selecting the grading face.

Grade Determining Face

2


Figure 8.—Examples of hardwood factory grade 2 logs.

Upper loz

Siz - . Length 10’, diameter 11 atsmall end
Straightness ...........Straight

Soundness Sound

Cuttings More than * of its grading-face length is clear in

“twosections each 4 feet long

PP a
Length 9’, diameter 12” at small end

8 oe Straight
Soundness Sound
Cuttings... .More ihan “4 of its grading-face length is clear in

two sections and 3 feet long

_.Upperlog

Length 11’, diameter 18” atsmall end

eduction of 28 percent for 6% inches of abso-
Jute sweep (sweep less than 30 percent maxi-

Si
Straightness .

mum allowance)
Soundness Sound .
Cuttings More than % of its grading-face length is clear in
two sections 5 and 4 feet long
a a

Position _.Upperlog
..Length 16’, diameter 22” at small end.
percent deduction for 4 inches of absolute

sweep

Size .
Straightness .

Soundness ... ..20 percent deduction for rot (sweep and rot.
deductions less than 50 percent maximum
permitted)

Cuttings ................Rot limits cutting on grading face, but clear

cuttings of 4, 3, and 4 feet give more than the
required #4 of grading-face length

14


CONTENTS

THE HARDWOOD TIMBER RESOURCE

LOG GRADES IN GENERAL
Objectives of log grading
Poorest Log Concept
Hardwood log use classes
Other products
Grade defects and scalable det fee ts

DEFINITION AND APPLICATION OF
SPECIFICATIONS FOR HARD WOoD LOG
CLASSE ND GRADES .
Hardwood veneer-log class
Forest Service standard grades for larlvond
factory-lumber logs

Special instructions for factory: Togs

Surface features

End features
Construction-log lass (Ti
Hardwood local-use lng class
General grading prvedures

Scaling

Relation of scaling deductions {0 log

GRADES FOR FACTORY

land heavy limbers)

ling defects:

HARDWOOD TREE
LUMBER
SELECTED REFERENCES ...
APPENDIX
‘How to use los-grade inform ation is establish:
Jog values

Factory-lumbur lozs
TL Tables for muking interior

deductions

1
2
2
2
4
7

Reprinted with minor changes 1979,


HARDWOOD LOCAL-USE logs (fig. 16). Examples are presented in figure

LOG CLASS 17. Although this standard minimum log may

The standard minimum log as suggested by vary with species, locality, and economic con-

the Forest Serviee system is defined in the speci- ditions, its definition is essential to provide a
fications for miscellaneous ar Jocal-use class floor.

Figure 17.—Examples of local-use class logs.

se ANNI,
co

W

A 14-foot log 16 inches in diameter at the small end. It does not have
minimum cuttings required for a factory log. It is too crooked and
unsound to meet. construction specifications, Sweep and rot deduc-
tionsare lessthan 67 pereent,

A 12-foot log 18 inches in diameter at the small end. It does not have
the cuttings required for a factory log. It has no large knots and no
sweep, but it has an unsound heart for which scale deductions will be
less than 67 percent.

A 16-foot log 18 inches in diameter at the small end. It does not have
the cuttings required for a factory log, Although it is sound, several
knots aretoo large for the construction class.

A 16-foot log 20 inches in diameter at the small end, H does not have
the cuttings required for a factory grade 2 log because of the deep
spiral seams. It will not qualify as a construction log because of un-

sound heart.
23


Abstract

A GUIDE TO HARDWOOD LOG GRADING (Revised) was de-
veloped as a teaching aid and field reference in grading
hardwood logs. Outlines basic principles and gives de-
tailed practical applications, with illustrations, in grading
hardwood logs. Includes standards for various use classes,

The Authors

EVERETTE D, RAST received his bachelor of science de-
gree in forestry from the University of Missouri in 1960 and
his master of science degree in agricultural economics from
Ohio State University in 1970. He joincd the U.S. Forest
Service in 1960 as a forester on the Mendocino National
Forest and in 1966 transferred to the Northeastern Forest
Experiment Station, He has served since that time as a re-
search forest products technologist on the quality and grade
of hardwood timber project at Columbus, Ohio.

DAVID L, SONDERMAN, research forest produets technol-
ogist, received his bachelor of science degree in forestry from
West Virginia University in 1962. He joined the Northeastem
Forest Experiment Station in June 1962 and was formerly
on the staff of the eastern softwood timber quality project
until June 1972. He is presently with the Northeastern Sta-
tion’s project on quality and grade of hardwood timber at
Columbus, Ohio.

GLENN L. GAMMON, a research forest products technolo-
gist, received his bachelor’s degree in forestry from the Uni-
versity of Georgia, and his master’s degree in wood technology
from the University of New Hampshire. He joined the Central
States Forest Experiment Station in 1963, He is presently on
the staff of the Northeastern Station’s hardwood timber qual-
ity project at Columbus, Ohio.

MANUSCRIPT RECEIVED FOR PUBLICATION 20 AuGUST 1971.


THE FOREST SERVICE of the U. S. Depart-
cculture is dedicated to the principle of
ment of the Nation's forest re-
ed yields of wood, water, forage.

meat of £

ltiple use an

urces fur sustar

arch,

wildife, and recreation. Through forestry res
a y
with the States and forest

nal Porests

cooperati

owners, and management of the Natio
and National Grassiands, it strives — as directed
by Congress-.to provide increasingly greater

ice to a growing Nation


sweep depends on log length as follows:° 8 feet the grading rulcs does not upgrade the log,
thru 10 feet . 1, 11 feet thru 13 feet -- 144, even though in some cases it may appear that

and 14 feet thru 16 feet — 2. the existence of a rotten heart center, for which
- scaling deduction is made, would raise the aver-
Relation of Scaling Deductions age grade of usable lumber produced. Parts of

to Log-Grading Defects
In general, making a scaling deduction from
the scale of a log up to the limits indicated in

the portion for which deduction is made may
or may not affect clear cutting areas. If they
do, they are individual log grade defects.

3 See Table 8 for «duction percentag:

Table 5.—Sweep deduction from gross scale by length
and diameter (in percent; based on rule 3)

Absolute sweep Scaling diameter, average small end
in inches inside bark, in inches

10 14-15-16 5 2 0 22 2 5
totam: teat lows 8 10 2 14 16 18 20 22 2% 2% 28 30

= 3 44° «3
3 4 8 7 7
4 5 2 10
5 6 5 14 13
6 7 19 18 17
7 8 23 21 20
8 9 27 25 33
9 10 Bt 29 a7
10 u 35 8230
W 12 38 38688
w 3B 42 39 37
13 14 46 43 40
4 35 50 48 43
15 16 545047
16 7 5B 4 50
W 18 62 57 53
18 19 65 6157
19 20 — 64 60
20 a -_— 7-— = 8
21 22 a - ~— 6&7
11-12-13
foot logs
3 wo 1 2 1 9 8 8 7 6 6 5 5
4 3125 21 18 1 1 1 1 WW Ww 9 8
5 44 35 29 25 22 19 18 16 15 13 12 12
6 56 45 38 32 28 25 22 20 19 17 16 15
7 — 55 46 39 34 31 28 25 238 21 2 18
8 — 65 54 46 41 36 32 30 27 95 93 22
9 — — @ 54 47 42 38 34 81 29 27 5
10 — ~ — 61 538 47 42 39 35 33 30 28
ir — —- = — 59 53 48 43 40 37 34 32
2 — = = — 6 58 52 48 44 40 38 35
13 —~ — ~ —~ — 6 BB 52 48 44 41 38
4 —~ = = = ~~ ~— & 57 2 4B 45 42
1b —~ - = = -— = = BL BB 52 48 45
16 -- = - = ~ —~ 6 © 5% BB 48
wv ~~ SS  DOOD
18 — — ~ 63 5955
19 _ _ 7 62 BB
20 ~ 66 62

2 —

_Note: For odd lengths and half inches of sweep, deductions can be interpolated from the figures
given.

26


Figure 4.—Northern Hardwood Veneer Log Specifications.»

Grading Factors

Specifications

T. Length

8 feet and over plus 6 inches trim allowance.”

smail end.

inches d.i.b.

4 inch per foot of log length

1 admitted in logs of all lengths and diameters if
it can be contained in a 2-foot long scaling reduc-
tion from either end, or from within the log pro-
| vided that a cutting at least 52 inches long re-
mains on each side of the scaled out po

5. Spiral Grain (maximum)

Uy inch per foot of log length |

6. Crotch Crotch admitted in logs of all diameters provided
it can be cut off by deducting 1 foot of Jength in
sealing, -

7. Seam None admitted which enter the right cylinder in

8. Standard Defect (other than seam)

Knots, worm holes, dead or rotten
arcas, high humps (with height over

length ratio greater than 1 to 6),
heavy bark distortions and old bird
pecks (4 or more per sq, ft.)." Treat
any number as 1 standard defect
when located not more than 10
inches from an end or so located that
they can he included in a 1-foot re-
duct ion, in log length when the log
scaled,

. End Defes
A. Black heart and/or mineral stai

“RB. Hole, rot, ring shake, loos
spider heart, and heart checks

or

logs 12, 13, and 14 inches d.ib. Logs 15 inches
| dab. and larger admit one seam, entering the right
linder, provided that it diverges from a straight
line between the Jog ends no more than 1% inch
per foot of log length. Such a seam constitutes 1

andard defect.

One standard defect admitted in logs 8 through
10) feet long, 2 in logs 12 feet and, 3 in logs 14
through 16 feet.

‘Admitted in hard maple logs when not in excess
of £4 the scaling diameter.

dmitted when confined to a central core around
the geometric center of the log end and the last
2 feet of log length—subject to scaling reduction."
After scaling reduction: Logs 12, 13, and 14
inches d.i.b. can contain central core with long
axis no longer than 3 inches; logs 15 inches d.i.b.
can contain central core with long axis no longer
than 4 inches; and logs 16 inches and over d.i.b.
can contain central core with long axis no longer
than 6 inches.

. Knots, partial ring shake, worm
holes, bird peck: ain spots, in-
cipient rot areas, and bark pock-
ets

Admitted to all logs outside the central core (9B)
when confined to a 4 segment of one end. When
occurring on both log ends, must be confined to
same 14 segment in logs 12 through 15 inches
ditb., can be in different 14 segments in logs 16
inches d.i.b. and larger.

inly for northern
pied by most mil
1

* Recommended 1

unsound central core (9B) and sweep (3)
ous subject to 2 foot se
face defects over the 2 feet so treated (8)

ies of heech, birch, maple and cherry.

6 foot lengths are accepted by most mills for black walnut
14 inches and aver dh,

mast be free of all defect except for the allowable

ing reduction in length due to unsound central core (9B) permit unlimited sur-

10


Figure 7.—-Examples of hardwood factory grade 1 logs.

_ Butt log

Size “Length 16", diametor 13” at smallend
Straightness |. Straight

Soundness Sound

Cuttings More than 5/6 of its gvadins-face length is clear

in twosertions 7and & feet long

8 6"

Position

Straightness

Soundness

Cuttings More than 5/6 of its grading-face length is clear
in one section 8 feet 6 inches long

Position Upperlog
28 ome “Length 12, diameter 20” at small end
Straight
Sound
Cuttings 000 005/6 of its erading-tace length is clear in two sec-

tions8 and 3 feet long

Position wa Upper fog

Size _... Length 16’, diameter 20" at small end

Staightness 16 percent deduction for 4” of absolute sweep

Soundness 5 percent deduction tor center rot (sweep and
rat deductions less than 40 percent maximum
permitted )

Cuttings One cutting 16°

Comments ... _ Rot is confined to per ble vot zone and does

not affect clear grading face

18