-
THE RELATIVE FUEL VALUE
of
OLD GROWTH SLAB AND SECOND GROWTH CORDWOOD
by
Lee Gable
A Thesis
Presented to the Faculty
JAN
e
of the
6
1958
School of Forestry
Oregon State College
In Partial Fulfillment
of the Requirements for the Degree
Bachelor of Science
June,
1959
Approved:
Professor of Forestry
THE RELATIVE FUEL VALUE
of
OLD GROWTH SLAB AID SECOND GROWTH CORDWOOD
by
Lee Gable
Introduction
The objective of this thesis is to determine the difference in the heat value of old growth slab and second
growth cordwood.
This question is one which has been wide-
ly discussed among fuel dealers
wood for fuel.
Although
niany
and those persons who burn
arguments have been given why
one wood Is superior to the other, very few of the arguments
have had more behind tern than mere opinion or prejudice and
actual facts have been noticeably absent.
been made herein to establish
s
An endeavor has
basis from which an impar-
tial decision on the fuel value of the two woods can be nade.
Importance of Problem
This question is of importance to fuel dealers,
saw-
mill operators, owners of timber and the consuming oublie.
The fuel dealers are interested because their sales would
naturally be larger in the wood that gives the most heat and
is the cheapest.
Because of the fact that slabwood is a
waste product and is manufactured chief ly by machinery, lt
2
has an advantage over the second growth wood which is not a
waste product and must be cut by hand.
Therefore,
second
growth wood must bring a higher price than the slab if it is
to be profitable to the producer.
Sawmill operators are greatly interested because selling
slabwood is the simplest way of getting rid of the waste from
the log at a profit.
Although they have the advantage in
being able to sell at a lower price,
there are certain charac-
teristics of slabwood which limit its sale.
Slabwood usual-
ly comes in odd lengths and is notorious for the fine slivers
left on the wood by the headsaw.
Add to these drawbacks the
fact that it has less fuel value than the second growth cord-
wood and the slabwood's sales would suffer considerably.
The sale of cordwood offers a source of income to the
owner of second growth timber which might well mean the dif-
ference between
hirn
delinquent taxes.
keeping the land or losing it through
If the timber owner is able to cut enough
wood during his thinning operations to pay his taxes and at
least partIally pay for the thinning, he will be more inclined
to keep his timber until it reaches maturity.
If the public
can be sold on the idea of using second growth cordwood so
much the better for the owner of second growth timber; therefore, he is vitally interested in whether the wood he can
produce is superior to slabwood.
The consumer stands to gain the most by knowing the
relative values of the two woods as
a
fuel.
He is free to
change from one to the other, so it makes little difference
3
to hirn which wood has the most fuel value as long as he finds
out which one it is so that he can buy that one.
Most people
favor old growth slabwood over second growth cordwood because
of Its heavy bark and the fact that it costs less.
Method of Procedure
All data here included is the result of tests and measurements made In an endeavor to set reliable standards from
which
a
fair comparison can be made.
The first step was to determine what percent of both
old growth slabwood and second growth cordwood was heartwood,
sapwood and bark.
This was done by taking a represen-
tative cord of slab wood and measuring the thickness of the
sapwood, heartwood and bark of each slab of wood.
These fig-
ures were recorded with the total thickness of each stick
also being recorded.
The average thickness of the slabs was
then figured and also the average thickness of the heartwood,
sapwood and bark.
The percent of the total that each formed
was then figured by dividing the thickness of each by the total thickness of the slab.
The same procedure was followed
for the second growth wood.
The next step was the collecting and drying of samples
of heartwood,
sapwood and bark for both the old growth slab-
wood and the second growth oordwood.
These samples were used
to determine the specific gravity or actual wood content of
the woods.
The samples were small, ranging in size from
one to two inches square.
They were placed in a small
4
electric oven to dry at a temperature of about 1040 C.
Each
day several of the samples were weighed and the weight recorded.
The same samples were weighed every
da.y
until the
weight ceased decreasing and remained the same for two days,
thus indicating that the samples were oven dry.
About a
week's time was necessary to get the samples down to oven
dry.
As soon as the samples were bone dry the specific gra-
vity of each was determined.
The equipment used for the
specific gravity determinations consisted of a set of scales
graduated to tenths of a gram, and a glass container for the
water in which the samples were weighed.
Each sam1e was
weighed three times and the scales balanced after each weighing.
Each. sample was
weighed dry, then dipped in paraffin
and weighed (the paraffin was to prevent the absorption of
water).
The final weighing was taken with the sample sub-
merged in water and held under by
a
long pin.
The specIfic
gravity was then found by the following method:
Weight of wood in water plus weight of paraffin
in water minus weight of paraffin in water equals
weight of wood in water.
Weight of wood in air Weight of wood in water
SpecIfic gravity
The slabwood samples used were picked at random from
slabwood piles at Hozeltine's Sawmill and the Corvallis
Lumber Company.
The specific gravity was determined on 150
samples in all, there being 25 each for the bark, sapwood
and heartwood of both the old growth and the second growth.
Samples which had not been dipped in paraffin were
then put in a ball machine and ground powder fine.
They
were later turned over to Mr. Thomas of the engineering
department who had B.T.U. tests run on them.
Summary
Findings:
Based on composite sample of 25 samples In mixture,
two tests on each B.T.U.
sample
OLD GROWTH SLAB
No. of
sample
Specific
gravity
% of
volume
per #
Heat
B.T.TJ.
Bark
25
.48
37
10,110
3740.7
Sap
25
.44
38
8,740
3321.2
Heart
25
.46
25
8,900
2224.0
9285.9
Total B.T.US per pound
Average specIfic gravity
.46
i
cord of wood contains 90 cu. ft. solid wood
i
cu.ft. water
=
.;3 x .37 :
X .38 :
.!
x .25 m
,1776
.1072
.lih
62.5 pounds
1J4O Avere pooitio gravity
62.5 z .1596 z 90 z 9286 a 21,O1O,1b7
3,T.1J.
per cord
SECOND GROWTH CORDWOOD
sample
SpecIfic
gravity
Bark
25
.43
6
10,150
609.0
Sap
25
.43
49
8,670
4248.3
Heart
25
.45
45
8,900
No. of
Heat
B.T.U.
per #
% of
volume
4005.0
8862.3
Total B.TITJ. per pound
Average specific gravity
:
.45
i
cord of wood contains 90 cu.ft. solid wood
i
cu.ft. water
62.5 pounds
£ot1 B..U. per poux4
.45 Z
e0(
z .149
.145Z.145.
836.3
CC
.2352
.2C
.Tö35
b2.5 z .Lô35 z 90 z
Average epeoifio gravity
&b2
- 23,078,692
,T.U. par oord
Conclusion
Relatively speaking the difference in the fuel value
of the two woods is slight.
The specific gravity of all
the samples tested was very close and the B.T.U. value was
also quite close except for the bark which was considerably
higher.
The old growth slab would give the most heat per
cord and because of its lower price would be the most eco-
nomical of the two.
7
Table i
OLD GROWTH SAP
Sample
Original
weight
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
10.0
5.9
14.2
7.2
10.0
11.4
8.9
11.5
10.4
11.5
14.1
12.2
9.3
10.6
12.8
10.8
8.0
9.6
10.0
12.6
9.1
6.9
7.5
'7.4
11.4
Paraffin Weight of
weight
paraffin
wood
plus weight
f
in water
of wood
11.2
6.9
14.9
8.0
10.5
11.8
9.7
12.9
10.8
12.2
14.9
13.5
9.9
11.6
13.1
11.9
8.5
10.2
10.7
13.8
9.9
7.6
7.8
7.8
12.1
Average Specific Gravity
24.2
13.5
29.9
17.5
24.6
25.1
20.8
26.4
26.0
29.3
32.8
30.4
23.2
24.1
27.5
23.0
21.6
21.1
24.2
26.9
23.2
16.3
20.0
18.7
28.3
Weight
of wood
Specific
gravity
in
water
23.9
12.4
29.1
16.6
25.0
24.6
19.9
24.9
25.6
28.5
31.9
29.0
22.5
23.0
27.2
21.8
21.0
20.4
23.4
25.6
22.3
15.5
19.7
18.3
27.5
.42
.48
.48
.43
.40
.46
.46
.46
.40
.40
.44
.42
.41
.46
.47
.50
.38
.47
.43
.49
.41
.44
.38
.40
.40
.44
Table 2
OLD GROWTH HEART
Sample
Original
weight
Paraffin
weight
weight
of wood
4.
i
2
3
4
5
6
7
8
9
lo
11
12
13
14
15
16
12.0
11.7
12.5
13.1
17.5
12.1
10.1
13.6
13.7
14.9
15.1
9.1
8.1
18.0
11.4
7.2
17
Es.8
18
19
20
21
22
23
24
25
15.6
10.4
10.7
8.9
11.0
11.2
5.7
9.0
12.7
13.3
13.5
13.6
18.5
12.6
10.5
14.0
14.1
15.6
15.5
9.2
8.2
19.3
11.9
7.4
9.2
16.4
10.7
11.0
9.2
11.2
11.8
5.8
9.2
Average Specific Gravity
Weight of
paraffin
+ wood
in water
29.4
26.8
22.7
28.0
41.3
28.1
21.2
30.1
29.3
33.1
31.7
18.2
18.2
39.4
21.3
18.8
20.2
31.2
21.6
19.8
19.8
21.5
22.0
10.9
19.0
Weight
of wood
Specific
gravity
in
water
28.6
25.0
27.6
27.4
40.2
27.5
20.7
29.7
28.9
32.3
31.3
18.1
18.1
38.0
20.7
16.6
19.8
30.3
21.3
19.5
19.5
21.3
21.3
10.8
18.8
.42
.47
.47
.48
.43
.44
.49
.46
.47
.46
.50
.50
.46
.47
.55
.43
.44
.51
.48
.55
.46
.51
.52
.53
.48
.48
Table 3
OLD GROWTH BARK
Sample
1
2
3
4
5
6
7
s
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Original
weight
18.2
12.1
17.2
41.3
19.4
13.0
14.0
24.5
11.5
20.4
22.5
20.7
14.5
22.5
29.9
10.5
29.5
26.4
30.1
21.6
16.1
10.7
22.1
20.2
11.3
Paraffin
weight
4 weight
of wood
18.3
12.9
18.8
43.1
23.5
15.5
14.6
26.5
12.5
21.2
24.0
21.5
15.0
24.2
30.3
10.9
30.8
27,8
31.2
23.2
17.2
10.9
23.4
21.1
12.8
Average Specific Gravity
Weight of
paraffin
wood
in water
40.0
27.5
38.3
89.6
51.1
29.2
30.4
55.1
26.0
48.8
43.6
48.4
30.2
45.9
60.4
25.2
60.0
53,3
67.6
50.6
39.1
24.3
47.4
46.2
28.4
Weight
of wood
SpecIfic
gravity
in
water
39.9
26.6
36.5
87.6
46.6
26.2
29.7
52.9
24.9
47.5
42.0
47.5
29.6
43.9
60.0
24.8
58.6
5 1.8
66.4
48.8
37.9
24.1
46.6
45.2
27.8
.46
.45
.47
.47
.41
.50
.47
.46
.46
.43
.53
.43
.49
.51
.49
.42
.50
.51
.47
.44
.43
.44
.47
.45
.40
.46
lo
Table 4
SECOND GROWTH SAP
Sample
Original
weight
Paraffin
weight
weight
of wood
.f
i
2
3
4
5
6
7
8
9
lo
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
15.7
9.8
16.2
12.1
12.6
15.2
17.7
16.1
16.4
22.4
14.0
10.0
12.7
12.4
11.0
18.5
21.0
15.4
21.5
14.8
11.8
14.7
12.4
15.0
21.7
16.3
9.9
17.4
12.3
L5.O
15.8
19.4
16.3
16.9
23.1
14.8
10.2
13.0
13.0
11.1
19.1
22.0
15.6
22.3
15.0
11.9
15.1
13.1
15.4
22.8
Average Specific Gravity
Weight of
paraffin
+ wood
in water
34.2
23.4
37.1
26.0
23.4
29.6
42.Z
32.5
30.6
34.8
31.3
24.3
24.2
30.0
28.3
33.2
59.5
30.0
42.6
37.4
24.8
30.4
24.7
31.8
44.6
Weight
of wood
Specific
gravity
in
water
35.54
23.29
35.80
25.88
23.O7
28.94
40.40
32.28
30.05
34.00
30.40
24.08
23.87
29.44
28.19
32.54
58.40
29.88
41.70
36.18
24.69
29.96
23.90
31.36
43.40
.47
.42
.45
.47
.55
.52
.43
.50
.54
.66
.46
.41
.53
.42
.39
.57
.36
.53
.51
.41
.48
.49
.52
.47
.50
.48
11
Table 5
SEC O1D GROWTH HEART
Saniple
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Original
weight
Paraffin
weight
f weight
of wood
23.4
13.0
17.2
9,3
6.9
25.85
14.0
10.7
25.0
14.8
17.6
9.8
7.0
26.5
14.4
11.6
7.8
9.2
17.6
5.75
14.7
9.1
9.3
19.3
14.7
12.4
17.1
14.6
9.8
9.1
11.6
5.9
7.0
p7.1
9.1
16.4
5.6
13.4
8.8
8.7
18.1
14.0
11.9
16.7
13.75
9.2
8.9
10.6
5.2
6.5
Average Specific Gravity
Weight of Weight
paraffin of wood
in
4 wood
water
in water
65.3
27.5
35.9
17.5
12.8
39.4
27.5
25.3
14.5
27.0
45.0
16.6
30.8
24.2
21.6
45.1
30.4
29.7
35.1
30.3
19.0
20.0
25.7
12.6
18.0
63.50
25.50
35.46
17.28
12.69
38.70
27.06
24.30
13.70
26.89
43.70
14.90
29.40
23.80
20.90
43.80
29.60
29.15
34.66
29.45
18.30
19.78
24.60
11.80
17.45
Specific
gravity
.35
.50
.48
.59
.54
.66
.51
.44
.52
.34
.37
.39
.46
.37
.41
.41
.47
.41
.48
.46
.50
.45
.43
.44
.37
.45
12
Table 6
SECOND GROWTH BARK
Sample
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Original
weight
22.3
17.8
13.1
7.0
9.2
17.2
9.2
7.3
13.2
10.6
17.5
10.9
17.8
7.6
10.1
9.2
17.8
9.4
9.6
10.1
17.8
8.7
9.4
8.9
13.3
Paraffin
weight
+ weight
of wood
24.6
20.3
15.5
7.2
10.0
18.5
10.1
8.0
14.1
11.6
19.3
11.8
19.8
8.8
11.5
11.0
18.6
10.0
10.9
10.4
19.3
9.1
10.7
11.6
14.6
Average Specific Gravity
Weight of Weight
paraffin of wood
wood
in
water
in water
SpecIfic
gravity
4.
49.3
47.5
30.0
16.2
19.9
38.6
25.6
17.5
27.5
24.8
40.0
25.7
41.9
17.2
29.2
22.3
42.4
27.7
21.0
31.6
39.6
20.4
24.5
25.0
29.9
47.90
43.70
28.30
15.98
19.00
37.40
24.60
16.70
26.50
23.70
38.00
24.70
39.70
15.90
27.70
20.30
41.50
27.00
19.60
31.27
37.90
19.96
23.06
22.00
27.46
.46
.41
.46
.44
.48
.46
.43
.50
.45
.46
.44
.42
.47
.40
.45
.43
.35
.49
.32
.47
.43
.47
.40
.41
.43