The Author 

Everette D. Rast, research 

forest products technologist, received a B.S. degree in forestry from 

the University of Missouri in 1960 

and an M.S. degree in agricultural 

economics from Ohio State University in 1970. He joined the Forest 

Service in 1960 as a forester on the 

Mendocino National Forest and 

transferred to the Northeastern 

Forest Experiment Station, Delaware, Ohio, in 1966. 

Manuscript received for 

publication 4 February 1982 

Abstract 

To properly classify or grade 

logs or trees, one must be able to 

correctly identify defect indicators 

and assess the effect of the underlying defect on possible end products. This guide aids the individual 

in identifying the surface defect 

indicator and also shows the progressive stages of the defect 

throughout its development. it illustrates and describes eight types of 

external defect indicators and associated defects that are particularly 

difficult to evaluate. 

ODC 852.11.121.1 31.171.19-(084.121) 
Introduction 

Hardwood tree- and log-grading 

systems are used to predict the 

volume and value of specified end 

products to determine the most 

valuable end use. To use the system, a basic knowledge of thearelationships between exterior defect 

indicators and underlying defects is 

needed. 

Many publications have been 

written on hardwood defect indicators, associated interior defects, 

and their effect on end products. 

Some of the publications have excellent photographs and descriptions of the defect indicators, but 

most have only one photograph of 

the defect as it appears in the interior of the log. However, Marden 

and Staytsn (1970) and Frederick 

and co-workers (1973) working with 

sugar maple and black cherry, respectively, showed up to three 

views of the defects at various 

depths within the logs. 

By conducting this study at a 

veneer slicing plant, 1 was able to 

trace the effect of a defect from its 

origin (or the backing board) to its 

terminus (or to the initial slice of 

veneer). Also by working with 

veneer, I was able to photograph 

changes in the defect characteristics as close together as 1128 of an 

inch (one sheet of veneer), if desired. This study is the first in a 

series of pictorial guides by species 

or species groups. 

Procedure 

Twenty-five northern red oak 

logs exhibiting 46 selected defect 

indicators were selected from the 

log deck of a veneer plant in southwestern Pennsylvania. The following 

eight defect indicators appeared approximately five times each: adventitious buds; adventitious bud 

clusters; heavy, medium, and light 

distortions of knot overgrowths; 

overgrown wounds; bumps; and 

insect borer damage. These defects 

were selected because they are difficult to recognize on the surface of 

the log and their effect on the end 

product is difficult to evaluate. 

The study logs were placed on 

stringers and washed using a medium-pressure water jet so the defect 

indicators could be photographed 

clearly. Lines were painted on the 

log ends to show where the log 

would be sawed for half-round slicing. Each log half was numbered to 

identify it throughout the veneering 

process. Defect indicators located 

in the center one-third (across the 

face) of the half-log were selected, 

identified, and their dimensions and 

distance from each end of the log 

were recorded. Log diameter and 

bark thickness were measured 

where each defect indicator occurred. The logs were then debarked 

and sawed into two flitches (Fig. 1). 

Before putting the flitches into the 

steam vats, an outline of both ends 

of each flitch was traced on a 

sketch pad. These outlines were 

used to determine wood loss between the bark and the initial slices 

of veneer. The length of the spurredoff veneer was measured on both 

ends of the flitches as they were 

sliced to aid in relocating and 

identifying the correct defect in the 

veneer by distance from the log 

ends. 

Jacket Boards (slabs) 

Flitch T-- 

Backing Board 

Figure 1.-A 2-flitch log showing sawing method and components. 
After drying, black and white 

photographs of the defects were 

taken with a 2-If4 x 2-114-inch single 

lens reflex camera. The individual 

defects in the veneer were correlated with the surface defect indicators by using the flitch number 

and location on the face of the veneer. The sheets of veneer were 

placed on a section of dead roils to 

facilitate photographing several defects on a single sheet of veneer 

without moving the camera (Fig. 2). 

The first indication of the defect below the surface was photographed, 

and additional photographs were 

taken as the characteristics of the 

defect changed going down through 

the "book'of veneer. The photographs continued to the last sheet 

of veneer or until no indication of 

the defect remained. 

Discussion of Defects 

The defect indicators examined 

in this study are the most difficult 

to evaluate in terms of effect on end 

product quality. Graders normally 

have no difficulty recognizing the 

obvious grading defects such as 

bulges, burls, butt scars, forks, 

holes, seams, limbs, and so on. 

They do have difficulty with the 

eight types of defect indicators pictured in this guide. 

Distortions of knot overgrowths 

are particularly difficult to assess 

and their correct identification is important since the amount of clear 

wood between the bark surface and 

the end of the overgrown dead limb 

stub directly affects the number of 

sheets of clear veneer that can be 

produced from a flitch. 

Although this study involved 25 

logs exhibiting 46 defect indicators, 

only one of each of the eight defect 

indicators and the underlying defects are pictured. Each of the defect indicators shown is representative of that type. 

Descriptions below the surface 

indicators include defect size, 

which is the length (along the 

grain), width (across the grain), and 

height (above the normal bark surFigure 2.-Photography setup show~ng camera, dead rolls for rnovlng 

veneer, and square used to outlrne and show aefect size. Magnetrc 

numbers were placed on square to correlate log and defect to each 

photograph. 

face) of the indicator; log diameter 

at the defect, which is diameter rnside the bark; flitch thickness at the 

defect, which is the radial distance 

from the bark side of the flitch to 

the interior side of the backing 

board (Fig. 1); and log position. 

Depth below interior defects indicates distance below initial sheet of 

veneer. Accumulative veneer thickness is the distance from the inrt~ai 

slice of usable veneer to the top sf 

the backing hoard. 

Adventitious Buds 

Figure 3 shows how the bud 

trace can persist for an indefinite 

number of years, yet not produce an 

epicormic branch even though the 

bud trace starts at a depth of more 

than 7 inches below the surface of 

the log. A bud trace in art hardwood 

species has a pith, though the pith 

may be very hard, if not impossible, 

to see with the naked eye (Esau 

1960). In the wood surface, it normally appears as a grain distortion. 

Padventili~us Bud GIusters 

and Btbergrr?anrn epic or mi^ Knots 

Adventitious bud clusters and 

overgrown epicormic knots frequently are found together. When 

one epicarmic branch forms, more 

adventitious buds lend to develop 

and Corm a clus"rer of short-lived fine 

limbs or twigs. Bark pockets commonly are associated with these defects. 

Figure 4 shows an adventitious 

bard that developed and sprouted into an epicormic branch. The branch 

died and a bark pocket formed. 

Other adventitious buds are afso 

evident in figure 4. 
Figure 3.- Adventitious bud and assocrated internal defects 

Defect size . . . . . . . . . . . 112 x 112 x 1/2 inch 

Log diameter at defect . . . . . . . 20.0 inches 

Flitch thickness at defect . . . . . 8.9 inches 

Log position . . . . . . . . . . . . . . . . . butt log 

Depth-0.3 inch 

Depth-2.8 inches Depth---4.3 inches 

Accumulative veneer 

thickness---5.6 inches 
Figure 4.-Adventitious bud clusters, overgrown epicormic 

associated internal defects. 

knot, and 

Defect size ............ 2 x 3 x 314 inches 

Log diameter at defect ....... 16.9 inches 

Flitch thickness at defect ..... 7.9 inches 

Log position ................. upper log 

Depth-0.0 inch 

Depth-1.0 inch 

4 

Depth-2.0 inches 
Depth-3.0 inches Depth-3.5 inches 

Depth-4.0 inches Depth-4.5 inches 
Depth----5.2 inches Depth---5 7 inches 

Accumliialrve 

veneer thrcKness--5 7 inches 

Knot Overgrowths bark pattern shows only slight variance from normal. ~escause-the de- Knot overgrowths--those with fect is deeply buried, the irregular no height measurements-are sub- bark patterns are almost inconspicu- divided into three categories: heavy, ous and can be easiiy overlooked. medium, and light distortions. A 

heavy distortion (Fig. 5) will cause 

the most degrade or volume loss rn 

the end product. It is identified by 

the characteristic pattern of concentric circles encompassing the 

defect indicator. Medium distortions 

(Fig. 6) show signs sf the concentric 

circles, but the circles are broken in 

several areas by the normal bark 

pattern starting to reform. The light 

distortions (Fig. 7'1 show only a 

slight amount sf curvature in the 

surrounding bark piates, and the 

All the knot avergrowths will resuit in some product degrade, but 

the amount sf degrade decreases as 

the depth of "Ie initial defect below 

the log surface increases. This is 

substantiated by the examples. Because the three distortions (Fig. 5, 

6, 3) are on logs of similar size, 

actuai comparisons can be made, 

The number of slices @f veneer before the actual defect appears is: 

heavy distortion-0, medium elislorlion-1 12, and light distortion-"182, 

Text continued on page 12 
Figure 5.-Knot svergrs&"r {ileatvy drstcrr~on; and 

associated internal defects 

Defe@"islze 2 412 x 3 inches 

Leg dsarneter at defect 26 3 inches 

Flitch thickness atdeer'ec: 9 "inches 

Log psss~ron dpper tog 

Destk-0.0 inch 
Depth-2.0 inches Depth-3.0 inches 

Depth-3.5 inches Depth-4.0 inches 

Accumulative veneer 

thickness-6.3 inches 

Depth.-5.5 inches Depth-6-5 inches 

Depth---T,B inches 

Accumulative veneer 

thickness-7.8 inches 
F~gure 7.- Knot overgrowth flight drslortton) and 

associated internal defects. 

Defect size ............ .2 112 x 2 inches 

Log diameter at defect. ...... 22.5 inches 

Flitch thickness at defect .... 10.1 inches 

Log position ................. upper log 

Depth-6.5 inches 

Depth-6.7 inches Dep"r-7,0 inches 
Depth-7.5 inches Depth-7.7 inches 

Accumulative veneer 

thickness-7.7 inches 

Overgrown Wounds 

Two types of wounds that 

cause little or no grade defects are: 

new wounds (1 year old or less) that 

are slabbed off, and old, deeply 

buried wounds that healed over 

completely before deterioration began and are now located in the 

heart center. Figure 8 shows an old, 

overgrown sound wound with some 

ingrown bark. This defect is located 

in the heart center, which is defined 

as the central portion of the log 

with a radius equal to 20 percent of 

the total log diameter (Rast et al 

1973). In figure 8, the diameter c 

the log at the defect is 17.0 inct.4- 

therefore, the radius of the heart 

center is 3.4 inches. The backing 

board is 1.5 inches thick, and the 

distance to the last trace of the defect is 1.9 inches; therefore, the 

product defect is well within the defined heart center. Although there 

are 28 sheets of veneer containing 

this defect, the grade of these final 

sheets before the backing board 

normally is very low. 
jeuia~ut ap 'si=tag 

j -33 umoifj~an~ purio~ pue palerDosse 
Depth-5.2 inches Depth---5.4 inches 

Acclamkilative veneer 

thickness-5.4 inches 

Bumps 

Almost 130 percent of all bumps 

cover limb stubs, adventitious bud 

clusters, ingrown bark: or a combination of these and therefore, cause 

a produc"reefecl. Sumps are classified as high, medium, or low bumps 

according to their height to length 

ratio (Rast et ai. 4973). The bump in 

figure 9 is a low bump. As seen in 

this figure, even Taw bumps contain 

defects veq close to the: 109 surface?, with vev lit"rle, if any, clear 

wood over it. Bumps are distinguished from overgrown knots by 

the absence sf concentric circles 

and the relative smooth and regular 

bark pattern over the defect. 
Figure 9.--- Blimp ([OW) and associared internal defects. 

Defect size. ........... 4 x 4 x 112 inches 

Log diameter at detect. ...... 23.6 inches 

Flitch thickness at defect .... 10.1 inches 

tog position ................. upper Isg 

Depth----0.0 inch 
Depth-3.0 inches Depth-4.5 inches 

Depth-5.5 inches Depth-7.0 inches 
Depth-7.3 inches 

Accurnutat ive veneer 

thickness-7.3 inches 

Figure 10.-Borer damage and associated internal defects. 

Insect Borer Damage 

Insect borers cause considerable product damage depending on 

the severity, location, and timing of 

their attack. New, or relatively new, 

successful attacks (Fig. 10) are very 

damaging in face veneer. Older attacks confined to the heart center 

or a limited number of attacks in 

products where plugging is allowed 

are less damaging. Although the 

hole extends only 1.4 inches into 

the actual veneer in the example, it 

is very damaging because highquality veneer is recovered near the 

outside of the log. 

Defect size . . . . . . . . . . . . . . . 112 x ti2 inch 

Log diameter at defect . . . . . . . 21.4 inches 

Flitch thickness at defect . . . . . 9.8 inches 

Log position . . . . . . . . . . . . . . . . . . butt log 

Depth-1.0 inch Depth-1.4 inches 

Depth-1.4 inches 

Accumulative veneer 

thickness-5.8 inches 
Selected References 

Esau, Katherine Anatomy of seed 

plants. New Vork: John Wiley & 

Sons, lnc.; 1960. 376 p. 

Frederick, Douglas J.; Koch, 

Christian B.; Carveil, Kenneth L. 

The relationship between certain 

external characteristics and internal defect in black cherry. Morgantown, WV: West Virginia University Agricultural and Forestry 

Experiment Station; 1973; Bull. 

615. 15 p. 

Harrar, E. S. Defects in hardwood 

veneer logs: their frequency and 

importance. 1954; USDA For. Serv. 

Res. Pap. SE-39. 45 p. 

Harrar, E. S.; Campbell, R. A. The 

major defects in southern hardwood veneer logs and bolts. 1966; 

USDA For. Serv. Res. Pap. SE-19. 

23 p. 

Lockard, C. R.; Putnam, J. A.; Carpenter, R. D. Grade defects in 

hardwood timber and logs. U.S. 

Dep. Agric.; 1963; Agric. Handbk. 

No. 244. 39 p. 

Lutz, John F. Wood and log characteristics affecting veneer production. 1971; USDA For. Serv. Res. 

Pap. FPL-150. 31 p. 

Marden, Richard M; Stayton, Charles 

L. Defect indicators in sugar maple-a photographic guide. 1970; 

USDA For. Serv. Res. Pap. PIC-37. 

29 p. 

Rast, Everette D.; Sonderman, David 

L.; Gammon, Glenn L. A guide to 

hardwood log grading. 1973; 

USDA For. Serv. Gen. Tech. Rep. 

PIE-1. 32 p. 

Stayton, Charles L.; Marden, Richard 

M.; Buchman, Roland G. Exterior 

defect indicators and their associated interior defect in sugar maple. For. Prod. J. 20(2):55-58; 1970. 

*U. S . GOVERNMENT PRINTING OFFICE : 2000-650- 336 / 20009 
Rast. Everette D. Photographic guide of selected external 

defect indicators and associated internal defects in 

northern red oak. Broomall, PA: Northeast. For. Exp. Stn.; 

1982; USDA For. Serv. Res. Pap. NE-511. 20 p. 

To properly classify or grade logs or trees, one must be able 

to correctly identify defect indicators and assess the effect of 

the underlying defect on possible end products. This guide 

aids the individual in identifying the surface defect indicator 

and also shows the progressive stages of the defect 

throughout its development. It illustrates and describes eight 

types of external defect indicators and associated defects 

that are particularly difficult to evaluate. 

Keywords: Defect identification; photo guide; northern red 

oak; quality assessment. 

ODC 852.11.121.131.1 71.19-(084.121) 
Headquarters of the Northeastern Forest Experiment Station are in 

Brmmalll, Pa. Field laboratories are maintained at: 

@ Amherst, Massachusetts, in cooperation with the University of 

Massachusetts. 

@ krea, Kentucky, in cooperation with Berea College. 

@ Burlington, Vermont, in cooperation with the University of 

Vermont. 

@ Delaware, OGa. 

@ Durham, New Nmpshire, in cooperation with the University of 

New Hmpkit-gt. 

@ Harmden, Gonn~ticut, in cooperation with Yale University. 

@ Morgmtown, West Virginia, in cooperation with West Virginia 

University, Morgmtown. 

@ Orono, Maine, in cooperation with the University of Maine, 

Orono. 

@ Paamns, West Virginia. 

@ Rhceton, West Virginia. 

@ Syrracw, New York, in cooperation with the State University of 

New York College of Environmental Sciences and Forestry at 

Sy sacuse Univemity , Syracw . @ University Park, Pennsylvania, in coopration with the 

Pennsylvania Slate University. 

@ Warren, knnsylvmia.