United States 

Department of 

Agriculture 

Forest Service 

Northeastern 

Forest Experiment

Station 

Research Paper NE-617 

 

Everette D. Rast 

John A. Beaton 

David L. Sonderman 

Photographic Guide to Selected 

External Defect Indicators and 

Associated Internal Defects in 

Black Walnut 
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 for black walnut. It illustrates and describes 

10 types of external defect indicators and associated defects that are particularly difficult to 

evaluate. 

The Authors 

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 and to Princeton, West Virginia, in 1987. 

JOHN A. BEATON, forestry technician, received his certificate as a forest technician from

Lake City Junior College and Forest Ranger School, Lake City, Florida, in 1964. He joined

the Forest Service in October 1964 as a forestry aid at the 

Forest Insect and Disease Laboratory, Delaware, Ohio. In November 1976, he transferred 

to Project 1351, Northeastern Forest Experiment Station, Delaware, Ohio, as a forestry

technician. 

DAVID L. SONDERMAN, research forest products technologist, joined the Northeastern 

Forest Experiment Station in 1962 and was on the staff of the Eastern Softwood Timber 

Quality project until 1972. From 1972 to 1987 he was located at Delaware, Ohio, with the 

Northeastern Station's project on management and utilization alternatives for nonindustrial 

private forests. He is currently with the Station's Forestry Sciences Laboratory at Princeton, 

West Virginia. 

Manuscript received for publication 27 October 1987. 

Northeastern Forest Experiment Station 

370 Reed Road, Broomall, PA 19008 

May 1988 
Introduction 

This photographic guide on black walnut is the third in a 

series to aid in the understanding of the relationship between 

exterior defect indicators and the underlying defect. This study,

unlike the two previous studies - northern red oak (Rast 1982) and 

black cherry (Rast and Beaton 1985)-was conducted at the Forest 

Products Laboratory in Madison, Wisconsin. Also in this publication

we provide a stereo pair of photographs of the defect indicator to 

give the user a more realistic view. 

counted and those necessary for photographing were saved. Once 

the veneer started coming off in a continuous sheet, it was clipped 

at the notch in the small end and stacked by bolts. The bolt number

was put on the first and last sheet of veneer of each bolt. Only 10 to

15 bolts were sliced at a time so the defects could be photographed 

the same day to prevent stain or discoloration. Then the veneer was 

put in cold storage before drying. 

Discussion of Defects

Procedure 

Thirteen black walnut trees located on Tar Hollow State 

Forest in south-central Ohio were selected, felled, and bucked into 

thirty 4-foot bolts containing the defects selected to be studied. 

Many of the bolts contained two or more defects. The bolts were 

carefully transported to a warehouse to be photographed. This 

controlled environment enabled us to take quality defect indicator 

photographs and provided a good storage area for the bolts until the 

initial film was developed and checked. 

The defect indicators reported in this publication are suppressed 

bud; suppressed bud cluster; open and occluded bird peck; light, 

medium, and heavy distortions; sound wound; hole (woodpecker); 

and gun shot wound (slug). We feel that these are often difficult to 

identify and evaluate in terms of their effect on end-product quality.

Graders normally have little difficulty recognizing and evaluating the 

obvious grading defects such as limbs, forks, bumps, or butt scars. 

The photo format utilized in this publication for each evaluated defect

is a pair of stereo photographs of the defect indicator on the log 

surface and next an enlarged set of prints, first of the defect indicator 

then a series of prints of the actual defect as it appears at different 

depths below the log surface. Below the photo of the defect indicator 

(Fig. 1) is a list that describes the size of the defect in terms of length 

(along the grain), width (across the grain), and height (above the 

normal bark contour); log diameter, inside-the-bark at the defect; 

round-up thickness; core diameter; and distance of defect above the 

stump. The information listed below the interior defect (Fig. 1) 

indicates distance below the log surface (inside the bark-ib) as well 

as the distance from the first slice of veneer to that particular 

photographed defect. The last photograph in each defect series also 

lists total veneer thickness, which is the distance from the initial slice 

of usable veneer to the veneer core. 

The ends of the bolts were marked off in quadrants using the 

geometric center as the midpoint. The quadrants were aligned to 

keep all the defects in quadrant 1 or 2 if possible. A 1-inch groove 

was routed along the 3-4 quadrant line, providing an identification 

mark in the rotary-cut veneer for clipping. By clipping at this point, 

each sheet of veneer was one complete revolution of the log. This 

provided a method for identifying the correct defect corresponding to

the surface defect indicator that was photographed. 

Prior to slicing, the bolts were heated in water and then debarked by

hand. The bolt was then chucked and rotary sliced into 1/10-inchthick veneer. Before getting a continuous sheet of veneer, the roundup pieces of veneer were 

1
Suppressed Buds 

Epicormic branches develop from two types of buds: sup 

pressed or dormant buds and adventitious buds (Kormanik and 

Brown 1969 and Shigo 1986). Suppressed buds (Fig. 1) can persist 

for many years just as a bud trace or can sprout suddenly after some

stimulus such as thinning or damage 

to the tree. Adventitious buds, on the other hand, form anew from the 

cambium usually following some injury to the tree. The defect 

indicator is normally associated with a slight break in the bark pattern

with a small protuberance in the center. 

Figure 1.-Suppressed bud and associated internal defects. 

Stereo view of defect indicator 

Defect size ................................................................

Log diameter at defect (ib) ..................................

Round-up thickness ..............................................

Core diameter ..........................................................

Defect distance above stump ..................................... 

1⁄2 x 1⁄2 inch 

14.3 inches 

0.1 inch 

6.3 inches 

4.0 feet 

Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.6 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 inches 

2
Depth below Depth below

Log surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. 2.0 inches Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.6 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .2.5 inches 

Depth below Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.1 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .3.0 inches Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.6 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. 3.5 inches 

3
Depth below Depth below 

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 inches 

Total Veneer Thickness. . . . . . . . . . . . . . . . . . . . . . . 4.5 inches 

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.1 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. 4.0 inches 

4
Suppressed Bud Cluster 

As the name implies, a suppressed bud cluster is a group of 

suppressed buds (3 to 20) tightly clustered in a small area, normally

less than 2x2 inches in size. Usually, but not always, there is 

evidence of concentric rings around the defect indicator. 

Figure 2 shows the faint lines of the concentric rings around the 

defect indicator and evidence of several individual buds. Also, the 

many adventitious knots are visible in the first defect photo. 

Figure 2.-Suppressed bud cluster and associated internal defects. 

Stereo view of defect indicator 

Defect size . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Log diameter at defect (ib) . . . . . . . . . . . . . . . . 

Round-up thickness . . . . . . . . . . . . . . . . . . . . . 

Core diameter. . . . . . . . . . . . . . . . . . . . . . . . . . 

Defect distance above stump. . . . . . . . . . . . . . 

1 1⁄2 x 2 x 1⁄2 inches 

13.7 inches 

0.5 inch 

6.2 inches 

8.0 feet 

Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.1 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. 1.6 inches 

5
Depth below Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.0 inches 

First sheet of veneer. . . . . . . . . . .. . . . . . . . . . . . . . . . 2.5 inches 

Log surface. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 inches 

Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.5 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. . 3.0 inches 

Total Veneer Thickness - 4.7 inches 

6
Bird Peck 

Bird peck is evaluated by determining vvhether callus tissue is 

formed in the peck holes (Rast et al. 1973). If the peck holes are 

open, the pecks did not reach the cambium layer and there will be no

damage; but, if the peck holes are closed, there will be damage to 

the tree. Sometimes bird pecks are called old or new. However, this

classification should not be used except to say that new bird pecks, 

whether or not they reach the cambium layer, can be disregarded in 

grading because if the tree is cut shortly afterwards, the peck defects 

will be removed during the initial stages of primary processing of

the log (debarking, slabbing, or round-up). 

Figure 3 shows a bird peck that is not occluded and, therefore, can 

be disregarded. No additional veneer photographs were taken 

because there were no indications of defects in the wood below. 

Figure 3. - Open bird peck. 

Stereo view of defect indicator 

Defect size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Log diameter at defect (ib). . . . . . . . . . . . . . . . . . . . . 

Round-up thickness. . . . . . . . . . . . . . . . . . . . . . . . . . 

Core diameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Defect distance above stump. . . . . . . . . . . . . . . . . . 

2 x 1⁄2 inches 

12.9 inches 

0.0 inch 

6.2 inches 

23 feet 

7
In contrast, Figure 4 shows very clearly the occluded callus material

that has formed in the pecked holes, and the 

defects are clearly visible in the underlying wood. 

Figure 4. - Occluded (closed) bird peck and associated internal defects. 

Stereo view of defect indicator 

Defect size. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Log diameter at defect (ib). . . . . . . . . . . . . . . . . . . . . 

Round-up thickness. . . . . . . . . . . . . . . . . . . . . . . . . . 

Core diameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Defect distance above stump. . . . . . . . . . . . . . . . . . 

1 x 10 inches Depth below

13.1 inches 

0.5 inch 

6.4 inches 

5.0 feet 

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 inches 

8
Depth below Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.5 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. . 2.0 inches 

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2.7 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 inches 

Depth below Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.2 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .2.7 inches 

Total Veneer Thickness - 3.3 inches 

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 inches 

9
Bark Distortions 

Bark distortions normally indicate, but not necessarily, an overgrown 

knot and are old enough that they exhibit no height measurement 

(flush with the normal contour of the bark). They are classified as 

light, medium, and heavy. A light bark distortion (Fig. 5) shows a 

slight amount of curvature in the surrounding bark plates, and the 

bark pattern varies only slightly from normal. Because of these 

features, light bark distortions are very inconspicuous and often over

looked. Medium bark distortions (Fig. 6) show more signs of the 

concentric circles, but they are broken in several areas by flat bark 

plates or the regular bark pattern. Also, there is usually a well-defined 

break in the bark pattern in the center of the defect indicator. Heavy 

bark distortions (Fig. 7) are normally identified by the characteristic 

pattern of concentric circles encompassing the defect indicator. 

Figure 5.-Light bark distortion and associated internal defects. 

Stereo view of defect indicator 

3 x 3 inches Depth below

13.6 inches 

0.5 inch 

6.3 inches 

14.0 feet 

Defect size. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Log diameter at defect (ib) . . . . . . . . . . . . . . . . . . . . . 

Round-up thickness. . . . . . . . . . . . . . . . . . . . . . . . . . . 

Core diameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Defect distance above stump . . . . . . . . . . . . . . . . . . . 

Log surface. . . . . . . . . . . . . . . . . . . . . . 3.5 inches 

First sheet of veneer. . . . . . . . . . . . . . . 3.0 inches 

10
Depth below Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.0 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .3.5 inches 

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.5 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . .. . 4.0 inches 

Depth below

Log surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 inches 

First sheet of veneer. . . . . . . . . . . . . . . . . . . . . . . . . . .4.5 inches 

Total Veneer Thickness - 4.5 inches 

11