ASTM D2395-93(1997)e2
(Test Method)Standard Test Methods for Specific Gravity of Wood and Wood-Based Materials
Standard Test Methods for Specific Gravity of Wood and Wood-Based Materials
General Information
Standards Content (Sample)
e2
Designation: D 2395 – 93 (Reapproved 1997)
Standard Test Methods for
Specific Gravity of Wood and Wood-Based Materials
This standard is issued under the fixed designation D 2395; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Editorial changes were made throughout in October 1997.
e NOTE—Equation X1.5 was corrected in November 2000.
INTRODUCTION
The specific gravity is the weight of any given volume of a substance divided by the weight of an
equal volume of water. As both the weight and volume of wood vary with the amount of moisture
contained in the wood, specific gravity as applied to wood is an indefinite quantity unless the
conditions under which it is determined are clearly specified. The specific gravity of wood is generally
based on the weight when oven-dry, but the volume may be that in the oven-dry, partially dry, or green
condition. The amount of moisture retained at any equilibrium condition is proportional to the dry
weight of the specimen, and for this reason moisture content is normally expressed as a percent of the
oven-dry weight of the wood.
1. Scope 3. Summary of Test Methods
1.1 These test methods cover the determination of the 3.1 The accuracy of the specific gravity value obtained on a
specific gravity of wood and wood-based materials to generally representative specimen will depend upon the accuracy of the
desired degrees of accuracy and for specimens of different measurements made. If the specimens are carefully prepared
sizes, shapes, and moisture content conditions. The method and regular in shape, the volume determined by Method A can
title is indicative of the procedures used or the specific area of be quite exact. The volume of irregularly shaped specimens
use. can best be determined by immersion in water or mercury and
if due care is taken to prevent absorption of water or entrap-
Section
Method A—Volume by Measurement 6
ment of mercury, Methods B and D will give results of great
Method B—Volume by Water Immersion 9
precision. Method C is an approximate method but a procedure
Method C—Flotation Tube 12
that can be very useful, particularly as part of a production
Method D—Volume by Mercury Immersion 15
Method E—Forstner Bit 18
procedure. Methods E and F are especially adapted to gravity
Method F—Increment Core 21
measurements of living trees or of in-place elements and the
Method G—Chips 24
accuracy of the result is dependent upon the care used in
1.2 This standard does not purport to address all of the
obtaining the specimen. Method G is a specific procedure for
safety concerns, if any, associated with its use. It is the
wood chips.
responsibility of the user of this standard to establish appro-
3.2 Conversion of Values—It may often be desirable to
priate safety and health practices and determine the applica-
convert the specific gravity obtained at one moisture content to
bility of regulatory limitations prior to use.
that at some other moisture content condition. This may be
approximated by the use of the chart in Fig. 1. The values of
2. Referenced Documents
specific gravity based on oven-dry volume or volume at the
2.1 ASTM Standards:
current moisture content, less than the fiber saturation value,
D 2016 Test Methods for Moisture Content of Wood
are read on the left-hand scale. The specific gravity values
based on green volume are plotted on the diagonal lines. All
values are based on oven-dry weight.
These test methods are under the jurisdiction of ASTM Committee D-7 on 3.2.1 To illustrate the use of the chart, assume the specific
Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental
gravity on an oven-dry weight and green volume basis is 0.55
Test Methods and Properties.
and it is desired to find the specific gravity for a 12 % moisture
Current edition approved Aug. 15, 1993. Published October 1993. Originally
content condition. Enter the chart at the 12 % moisture content
published as D 2395 – 65 T. Last previous edition D 2395 – 83.
Discontinued; see 1988 Annual Book of ASTM Standards, Vol 04.10.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2395
FIG. 1 Relation of Specific Gravity and Moisture Content
and move vertically to the point where this line intersects the intersection with the 15 % moisture content line and then
0.55 specific gravity value (between diagonals 0.54 and 0.56) horizontally to the left-hand scale to read 0.44.
and move horizontally to the left-hand scale to read the specific
4. Significance and Use
gravity value 0.60. If the specific gravity on an oven-dry
weight and volume basis is 0.54 and the specific gravity at 4.1 The specific gravity of wood gives an excellent measure
15 % moisture content is desired, enter the chart at 0.54 on the of the amount of wood substance present in a sample. Thus, it
left-hand scale and move parallel to the diagonals to an may serve as a valuable indicator of the amount of wood pulp
intersection with the 15 % moisture content line, then move that could be produced, the workability of the material, or the
horizontally to the left-hand scale to read 0.50. If the specific strength characteristics of a specimen or a species. It should be
gravity at 8 % moisture content is 0.45 and the value at 15 % recognized that specific gravity varies between trees, within a
moisture content is desired, enter the chart with 8 % moisture tree, and between species. Since the specific gravity of wood
content on the lower scale and 0.45 on the left-hand scale; from substance is practically constant for all species (approximately
this intersection move parallel to the diagonal lines to an 1.53), it is apparent that individual specific gravity values are
D 2395
indicative of the amount of wood substance present. It affords mity of the specimen, but at least three measurements of each
a rapid and valuable method for selection of wood for specific dimension will be required.
uses.
7.2 Weight—Determine the weight (W) of the specimen at
4.2 It may be desirable to know the specific gravity of a
the time of observation or test in accordance with 5.2.
living tree, a structural member already in place, a log cross
7.3 Moisture Content—Determine the moisture content (M)
section, a segment of a research element, or the earlywood or
of the specimen to permit description of the basis on which the
latewood layer. The specimen thus may be large or small,
specific gravity is computed. Test Methods D 2016 indicate
regular or irregular, and at a variety of moisture contents. This
procedures that should be used.
test method gives procedures that include all of these variables
7.3.1 Small Specimens—The entire specimen may be used
and provides for calculation of specific gravity values to
for determination of moisture content.
degrees of accuracy generally needed.
7.3.2 Intermediate Specimens—When the specimen is of a
size that is unsuitable for moisture content determinations (the
5. Test Specimens
time to oven-dry to constant weight would be excessive), a
5.1 The specific gravity specimens shall be fully represen-
segment may be cut from the specimen for a moisture content
tative of the material from which they are taken. The specimen
specimen. Select this segment so that its moisture content is
size shall be such that accurate measurements of weight and
representative of that of the larger specimen. Where possible in
volume are easy to attain. Where other standards specify the
solid wood elements, the moisture content specimen shall be of
location and size of specific gravity specimens, these require-
full cross-sectional dimensions and 1 in. (25 mm) in length
ments shall be carefully followed. The specimens shall be
(parallel to grain). In sheet materials the specimen shall be
carefully cut from the larger element to ensure clean-cut
equal in thickness to the thickness of the material and 3 by 6 in.
surfaces. All loose fibers shall be carefully removed before the
(76 by 122 mm) in size.
specimen is weighed and measured. The specimen shall be free
7.3.3 Structural Elements—In full-sized members, deter-
from knots, and if pitch or other infiltrates are present, this shall
mine the moisture content from a segment cut from the
be noted in the report or they shall be extracted before specific
member. It shall be of full cross-sectional dimensions and 1 in.
gravity values are obtained.
(25 mm) in length (parallel to grain), and shall be selected from
5.2 Measurements—The dimensions of test specimens shall
a representative area of the member. To avoid the effects of end
be measured to a precision of 60.3 % or less, and the weight
drying, cut the specimen at least 18 in. (457 mm) in from the
shall be determined to a precision of 60.2 % or less. Where
end of the member.
drying of specimens is required, this shall be done in an oven
7.3.4 Special Situations—Where the specimen or element
maintained at 103 6 2°C. (For most panel materials and wood
cannot be cut to secure a moisture content segment, an
specimens 1 in. (25 mm) in length parallel to grain, drying for
approximate moisture content may be obtained through the use
48 h in an oven having good air circulation and exchange will
of a moisture meter which is used in accordance with the
be sufficient to reach constant weight.)
manufacturer’s recommendations. Since the moisture content
5.3 Report—The report shall identify the material as com-
value is approximate, it should be recognized that the specific
pletely as possible, the method of selecting the specific gravity
gravity value obtained will also be approximate.
sample, the procedure used in determining the specific gravity,
7.3.5 Specimen Preparation—When the moisture content
and the conditions under which the volume and weight were
specimen is a portion of the element, remove all loose particles
determined.
from the specimen and determine the initial weight (I)in
accordance with 5.2.
METHOD A—VOLUME BY MEASUREMENT
7.4 Drying—Oven-dry the moisture content specimen to
constant weight in accordance with 5.2, and determine the
6. Applicability
oven-dry weight (F).
6.1 Shape of Specimen—The specimen must be regular in
shape with right-angle corners for determination of volume by
8. Calculation
lineal measurement. The procedure is adaptable to any size of
8.1 Moisture Content—Calculate the moisture content of
specimen or to specimens of any moisture content. If the
the specimen as follows:
surfaces of the specimen are smooth and sufficient measure-
ments are taken, the volume can be obtained with considerable
Moisture content, % 5 100 @~ I 2 F!/ F# (1)
accuracy. Special care must be taken in measurement of very
where:
small or thin specimens. Volume of irregular or rough-surfaced
I = initial weight, and
specimens should be obtained by Method B or Method D.
F = final weight (oven-dry).
7. Procedures 8.2 Specific Gravity—Calculate the specific gravity as fol-
lows:
7.1 Measurement—Measure the length (L), width (w), and
thickness (t) of the specimen in accordance with 5.2 in a sp gr 5 KW/@1 1 ~M/100!#Lwt (2)
sufficient number of places to ensure an accurate indication of
where:
volume. In small specimens, uniform in size, one or two
W = weight of specimen,
measurements of each dimension will suffice; in larger speci-
M = moisture content of sample, %,
mens the number of measurements will depend on the unifor-
D 2395
men at time of test in accordance with 5.2.
W/[1 + (M/100)] = calculated oven-dry weight of speci-
10.2 Volume—Determine the volume of the specimen by
men,
L = length of specimen, one of the following modes. Volume may be determined in the
w = width of specimen, “as received” condition if the specimen is green; or in the “as
t = thickness of specimen, and received” condition if the specimen is partially dry or after
K = a constant;
oven-drying if the pores are adequately sealed (see 10.2.5).
K = 27.68 when weight is in lb and volume
Determine the volume of the specimen by measuring the
is in in.
volume of water displaced or by determining the weight of the
K = 453.59 when weight is in lb and volume
water displaced. The weight in grams is numerically equal to
is in cm
the volume in cubic centimetres.
K = 453 590 when weight is in lb and
10.2.1 Mode I—Place the specimen in a tank of known
volume is in mm
volume and add sufficient water to fill the tank. Then remove
K = 0.061 when weight is in g and volume
the specimen and determine the volume of water remaining.
is in in.
The tank volume less the volume of water remaining is equal
K = 1 when weight is in g and volume is in
to the volume of the specimen. The relationship between
cm
specimen volume and tank volume shall be such that the
K = 1000 when weight is in g and volume is
3 precision of specimen volume measurement is high.
in mm
10.2.2 Mode II—Place a container holding enough water to
8.2.1 The specific gravity calculated is based on oven-dry
completely submerge the specimen on one pan of a balance as
weight and volume at test.
shown in Fig. 2. Then balance the combined weight of the
8.2.2 If the term [1 + ( M/100)] were removed from the
container and water with weights added to the other pan. Hold
formula, the specific gravity value would be based on weight
the specimen so that it is completely submerged without
and volume when tested, or at the moisture content when
touching the sides of the container by means of a sharp,
measured. If the measured moisture content were above the
pointed, slender rod and balance the scales again. The weight
fiber saturation point, the specific gravity would be based on
added to restore balance is equal to the weight of water
the green volume.
displaced by the specimen. Alternatively, an automatic balance
METHOD B—VOLUME BY WATER IMMERSION
may be used and will greatly facilitate the speed of such
measurements. If very small specimens are used, the accuracy
9. Applicability
of resulting data is likely to be low.
9.1 Type of Specimen—This procedure is particularly adapt-
10.2.3 Mode III—Place a container holding enough water to
able to specimens of irregular shape or having a rough surface.
completely submerge the specimen below one pan of a balance
Limitations on specimen size are based primarily on size of
as shown in Fig. 3. The container shall be sufficiently large so
immersion tanks available. In small size specimens, less than 1
3 that immersion of the specimen causes no material change in
cm in volume, air bubbles adhering to the specimen surface
water level. Suspend a wire basket of sufficient weight to ho
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