STEEXGTH TESTS OF STRUCTURAL TIMBERS. 
13 
SPECIAL TESTS OX SMALL PIECES. 
Table 3 gives a condensed summary of the results of a special series 
of tests on small clear speciments (2 by 2 inches in section) of Douglas 
fir, longleaf pine, and shortleaf pine. The tests were made at 
the Forest Products Laboratory to study the effect of the various 
steps used in the treatment of the full-sized stringers. Eight sticks 
were subjected to each of the processes shown in Table 3. One-half 
of the sticks were tested shortly after treatment and one-half after 
they had been piled in the laboratory long enough (5 months) to reach 
a practically constant weight. 
All the processes caused a reduction in the strength values of the 
unseasoned material of the three species with, in most cases, a recov- 
ery after seasoning, except in the tension tests. In these the weaken- 
ing in the unseasoned material remained after seasoning in all processes 
but the creosote bath. 
Table 3.— Effect of various treatments on small clear sticks (results expressed 1 in per cent 
of strength of untreated material) . 
Steamed at 
20 pounds 
5 hours. 
Steamed at 
20 pounds 
5 hours; 
26-inch 
vacuum 
1 hour. 
Unsea- 
soned 
Steamed at 
20 pounds 
5 hours; 
26-inch 
vacuum 
1 hour; 
creosote, 
120 pounds 
pressure, 
4 J hours. 
Air Unsea- Air Unsea- 
dry. soned. dry. soned. 
Air 
dry. 
Creosote at 
atmospheric 
pressure, 
200° F., 
27 hours. 
Unsea- 
soned. 
Air 
drv. 
Creosote bath 
at atmos- 
pheric pres- 
sure, 200° F., 
27 hours; 
creosote at 
145 pounds 
pressure, 
180° F., 
If hours. 
Unsea- 
soned. 
Air 
dry. 
Bending: 
Modulus of rupture — 
Douglas fir 74 
Longleaf pine 83 
Shortleaf pine I 73 
Modulus of elasticity — 
Douglas fir 87 
Longleaf pine ! 94 
Shortleaf pine I 84 
Compression: 
Maximum crushing 
strength- 
Douglas fir..... 68 
Longleaf pine 79 
Shortleaf pine 70 
Shear with grain- 
Douglas fir [ 72 
Longleaf pine 
Shortleaf pine 
Tension perpendicular 
grain— 
D ouglas fir 
Longleaf pine 
Shortleaf pine 
Shrinkage 1 in cross section 
during treatment- 
Douglas fir 
Longleaf pine 
Shortleaf pine 
During treatment and sea- 
soning — 
Douglas fir 
Longleaf pine 
Shortleaf pine 
to 
102 
102 
101 
I 93 
118 
107 
78 
93 
92 
76 
74 
74 
.13 
.42 
.33 
83 
8.58 
10.64 
10.47 
3.34 
.08 
.92 
5.35 
105 
112 
S3 
95 
.73 
"2*25' 
6.18 
5.94 
93 
106 
108 
100 
112 
87 
109 
125 
115 
115 
117 
67 
13(1 
7.46 
'7.50 
11.31 
7.90 
5.73 
1 Shrinkage given in per cents of areas when first measured. Corresponding shrinkage of untreated mate- 
rial; Douglas fir, 6.40; longleaf pine, 8.48; shortleaf pine, 7.29. 
2 Increase in volume. 
