ASTM C474-97

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C 474 – 97
Standard Test Methods for
Joint Treatment Materials for Gypsum Board Construction
This standard is issued under the fixed designation C 474; 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.
1. Scope C 475 Specification for Joint Compound and Joint Tape for
Finishing Gypsum Board
1.1 These test methods cover the physical testing of joint
D 685 Practice for Conditioning Paper and Paper Products
compound, paper joint tape, and an assembly of joint com-
for Testing
pound and paper joint tape.
D 828 Test Method for Tensile Properties of Paper and
1.1.1 Joint treatment materials are specified in Specification
Paperboard Using Constant Rate-of-Elongation Appara-
C 475.
tus
1.2 The test methods appear in the following order:
E 100 Specification for ASTM Hydrometers
Section
2.2 TAPPI Standard:
Joint Compound Tests:
Viscosity 5
T 410 Grammage of Paper and Paperboard (Weight Per
Shrinkage 6
Unit Area)
Check Cracking 7
Putrefaction 8
3. Terminology
Paper Joint Tape Tests:
Tensile Strength 9
3.1 Definitions—For definitions of terms relating to gyp-
Dimensional Stability 10
sum, see Terminology C 11.
Width 11
Thickness 12
3.2 Definitions of Terms Specific to This Standard:
Assemblages of Paper Joint Tape and Joint Compound:
3.2.1 bond, n—in joint systems, the quality of adhesion
Bond of Paper Joint Tape to Joint Compound 13
between the paper joint tape and joint compound.
Cracking of Joint Compound at Tape Edges 14
3.2.1.1 Discussion—A 0 % bond means that no paper fiber
1.3 The values stated in inch-pound units are to be regarded
is adhering to the joint compound. A100 % bond means that
as the standard. The SI (metric) values given in parentheses are
there is cohesive failure of the paper joint tape.
approximate and are provided for information purposes only.
3.2.2 check cracking, n—in joint systems, short, narrow
1.4 The text of this standard references notes and footnotes
cracks randomly oriented in the surface of the dried joint
which provide explanatory material. These notes and footnotes
compound.
(excluding those in tables and figures) shall not be considered
3.2.3 joint compound, powder, n—A drying-type or setting-
as requirements of the standard.
type cementitious material to be mixed with water.
1.5 This standard does not purport to address all of the
3.2.4 joint compound, ready-mix, n—A drying-type cemen-
safety concerns, if any, associated with its use. It is the
titious material that is factory mixed in ready-to-use form.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Specimen Preparation
bility of regulatory limitations prior to use.
4.1 Joint Compound, Powder:
4.1.1 Mix 300 g of joint compound, powder, with approxi-
2. Referenced Documents
mately 150 to 160 mL of water.
2.1 ASTM Standards:
4.1.2 Allow the specimen to stand for 30 min (Note 1),
C 11 Terminology Relating to Gypsum and Related Build-
remix and adjust the temperature to 77 6 2°F (25 6 1°C) by
ing Materials and Systems
placing the container holding the specimen in warm or cool
C 36 Specification for Gypsum Wallboard
water.
C 472 Test Methods for Physical Testing of Gypsum, Gyp-
sum Plasters, and Gypsum Concrete NOTE 1—Allow setting type compounds to stand for one half of their
setting times, as determined by Test Methods C 472 but not more than 30
min, prior to remixing.
These test methods are under the jurisdiction of ASTM Committee C-11 on
4.1.3 Measure the viscosity in accordance with Section 5.
Gypsum and Related Building Materials and Systems and are the direct responsi-
bility of Subcommittee C11.02 on Specifications and Test Methods for Accessories
and Related Products. Annual Book of ASTM Standards, Vol 15.09.
Current edition approved April 10, 1997. Published June 1997. Originally Annual Book of ASTM Standards, Vol 14.03.
published as C 474 – 61. Last previous edition C 474 – 96. Available from Technical Association of the Pulp and Paper Industry, Technol-
Annual Book of ASTM Standards, Vol 04.01. ogy Park, P.O. Box 105113, Atlanta, GA 30348.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 474
4.1.4 If the measured viscosity is not between 480 and 520 tracing remains inconsistent, estimate the average viscosity
Brabender units, repeat 4.1.1-4.1.3 through with an increase or reading.
decrease in water as necessary. 5.6 Report:
4.1.5 Record the volume of water used to adjust the viscos- 5.6.1 Report the viscosity of the joint compound specimen
ity to 500 6 20 Brabender units. (Note 2) in Brabender units.
5.7 Precision and Bias:
NOTE 2—Making note of the volumes of water, in millilitres per 100 g
5.7.1 Precision and bias of this test method have not been
of material, used to adjust the viscosity, will facilitate specimen prepara-
determined.
tion in other tests.
4.2 Joint Compound, Ready-Mix: 6. Shrinkage
4.2.1 Remix joint compound, ready-mix, to reincorporate
6.1 Significance and Use:
any separated ingredients. Adjust the temperature to 77 6 2°F
6.1.1 This test is used to measure the amount of shrinkage in
(256 1°C) by placing the container holding the specimen in
joint compound. The degree of correlation between this test
warm or cool water.
and service performance has not been determined.
4.2.2 Measure the viscosity in accordance with Section 5.
6.2 Sampling:
4.2.3 If the viscosity is more than 520 Brabender units, add
6.2.1 Sampling shall be in accordance with Specification
water to achieve a viscosity of 500 6 20 Brabender units.
C 475.
(Note 2)
6.3 Specimen Preparation:
4.2.3.1 If the original sample viscosity is less than 480
6.3.1 Specimen preparation shall be in accordance with
Brabender units, test as received.
Section 4.
6.4 Apparatus:
JOINT COMPOUND
6.4.1 Plastic or Rubber Film, approximately 5 by 5 in. (130
5. Joint Compound Viscosity
by 130 mm). Any thin, flexible film that peels clean from a
5.1 Significance and Use: partially dried patty may be used.
5.1.1 This test method provides a procedure for measuring 6.4.2 Balance, having a sensitivity of 10 mg (Fig. 1 and Fig.
joint compound viscosity. 2).
5.2 Sampling: 6.4.3 Beaker, Ring Stand, and Wire Cradle (see Fig. 1).
5.2.1 Sampling shall be in accordance with Specification 6.4.4 Forced Air Drying Oven, capable of being maintained
C 475. at 90 to 120°F (32 to 49°C).
5.3 Specimen Preparation: 6.4.5 Spatula, having a blade approximately 4 in. by ⁄2 in.
5.3.1 Prepare specimens in accordance with Section 4. (100 by 13 mm).
5.4 Apparatus: 6.4.6 Steel-Reinforced Broad Knife,a5to8in. (130 by 200
5.4.1 Viscosity Specimen Container, metal or plastic with an mm) drywall broad knife reinforced by a steel bar, 1 in. (25.4
1 1
mm) wide by ⁄8 in. (3.2 mm) thick, by the knife width,
open top having an inside diameter of 2 ⁄2 to 3 in. (64 to 76
1 1
mm) and a height of 2 ⁄2 to 3 in. (64 to 76 mm). attached to the back of the knife blade ⁄4 in. (6 mm) from the
edge.
5.4.2 Viscometer , adjusted to operate at 78 6 1 r/min, and
with a 250 cm-g sensitivity cartridge. 6.4.7 Hydrometer, having a range of 0.7 to 0.8 sp gr, in
accordance with Specification E 100.
5.4.3 Viscometer Pin, having dimensions as follows:
6.4.8 Volumetric Container, a container which has a volume
in. (mm)
Shaft diameter 0.187 6 0.015 (4.75 6 0.38)
between 25 and 300 cm .
Pin diameter 0.094 6 0.015 (2.39 6 0.38)
6.5 Reagents and Materials:
Immersion depth (from bottom of spindle) 1.625 6 0.015 (41.3 6 0.38)
6.5.1 Displacement Fluids.
Length of pin projecting from shaft 0.750 6 0.015 (19.1 6 0.38)
Upper pin from bottom of shaft 0.313 6 0.015 (7.95 6 0.38)
6.5.1.1 Minerals Spirits, odorless.
Lower pin from bottom of shaft 0.125 6 0.015 (3.28 6 0.38)
6.5.1.2 Kerosine.
5.5 Procedure:
6.6 Preparation of Apparatus:
5.5.1 Fill the viscosity container with the mixed specimen 6.6.1 Support Plates—Cover three plastic or glass plates
until level with the top of the container.
with plastic or rubber film.
5.5.1.1 Remove all air bubbles by puddling the sample 6.6.2 Obtain and record the tare weight of each assembly.
container with a spatula and sharply rapping the bottom of the
6.7 Calibration:
container on a hard flat surface.
6.7.1 Volumetric Container—Determine the container vol-
5.5.2 Lock the filled container in the center of the viscom-
ume in cubic centimetres and its tare weight in grams.
eter spindle platform. Raise the platform until the level of the
6.7.2 Mineral Spirits, Kerosine—Using the hydrometer, de-
specimen reaches the mark on the viscometer pin and lock the termine the specific gravity and record the result as M.
platform in place.
6.8 Determination of Wet Volume:
5.5.3 Start the viscometer. Read the viscosity after the pen 6.8.1 Prepare a specimen to determine the wet specific
starts to trace a straight line (usually within 1 min). If the
gravity by weighing the specimen in the volumetric container.
6 7
The Brabender “Visco-Corder” Model VC-3, manufactured by C.W. Brabender Rubber dental dam dusted with talc, polyethylene, or PTFE films have been
Instruments Inc., South Hackensack, NJ has been found satisfactory. found satisfactory for this use.
C 474
FIG. 1 Wire Cradle in Kerosine
6.8.1.4 Weigh the filled container to the nearest 0.01 g.
Record the weight of the filled container.
6.9 Preparation of Specimen to Determine Dry Volume:
6.9.1 Place approximately 30 g of specimen onto each
prepared support plate.
3 1
6.9.1.1 Spread the specimen into an elongated patty ⁄16 to ⁄4
in. (4.8 to 6.4 mm) thick with a spatula.
6.9.1.2 Remove any specimen remaining on the spatula and
add to the patty.
NOTE 3—The patty may be scored across its narrowest width to
facilitate breaking the patty after it is dry.
6.9.1.3 Weigh and record the total weight of each patty, film
and plate.
6.9.1.4 When testing setting type joint compounds, place
the patties in the drying oven one h after the setting time has
been reached as determined by Test Methods C 472.
6.9.1.5 When testing drying type joint compounds, place the
patties in the drying oven immediately after weighing.
6.9.2 Dry patties at a temperature between 100° and 120°F
(32° to 49°C) for 16 to 24 h.
6.9.3 Strip off the plastic or rubber film, and continue to dry
until constant weight is reached.
6.10 Determination of Dry Volume:
FIG. 2 Patty Immersed in Kerosine
6.10.1 Immerse each patty in a beaker of the displacement
fluid, such that they do not touch the sides of the beaker, until
6.8.1.1 Adjust the temperature to 77 6 2°F (25 6 1°C) by
constant weight is reached.
placing the container holding the specimen in warm or cool
NOTE 4—Each patty may be broken into two or three pieces to fit in the
water.
beaker without touching the sides.
6.8.1.2 Puddle the specimen with the spatula to remove
entrapped air bubbles. 6.10.2 Remove each patty from the displacement fluid.
6.8.1.3 Fill the container completely and strike off the Using a cloth moistened in the same fluid, lightly blot off the
surface flush with the top using the steel-reinforced broad excess fluid from the surface of the patty.
knife. 6.10.3 With the wire cradle suspended in the beaker of
C 474
displacement fluid, weigh each patty in air on the pan of the 7.4.3 Gypsum Wallboard, Specification C 36.
balance (Fig. 1), and record as its air weight. 7.4.4 Electric Fan, capable of forcing a continuous current
6.10.4 Next, weigh each patty in the wire cradle, making of air at a velocity of 350 to 450 ft/min (1.8 to 2.3 m/s) at a
sure that the patty is completely immersed in the liquid and that distance of approximately 3 ft (1 m).
it does not touch the sides of the beaker (Fig. 2). Record these 7.5 Procedure:
weights as the immersed weight. 7.5.1 Place the rod on a piece of gypsum wallboard and
6.11 Calculation of Shrinkage: place some of the specimen next to the rod.
6.11.1 Determine the net weight of the compound in the 7.5.2 Form a 3 ⁄2 to 4 in. (90 to 100 mm) wide wedge of the
volumetric container by subtracting the weight obtained in specimen with the steel-reinforced broad knife, with the rod on
6.8.1.4 from the weight obtained in 6.7.1. one side and the wallboard on the other side to guide the knife.
6.11.2 Divide the net weight obtained in 6.11.1 by the 7.5.2.1 Hold the broad knife at an angle less than 45° with
volume of the container obtained in 6.7.1. Record the result as respect to the plane of the wallboard. Draw the broad knife
G, grams per millilitre. over the specimen two or more times to leave the surface
smooth.
Total weight 2 Container tare weight
G 5
7.5.3 Remove the rod and adjust the wedge to a 5 in. (130
Volume of Container
mm) length.
6.11.3 Determine the net weight of each specimen by
7.5.4 Immediately place the wedge-shaped specimen in
subtracting the tare weight of its support plate weight and its
front of the fan blowing over the surface of the wedge for 8 to
weight obtained in 6.9.1.3.
16 h. The current of air shall be maintained at 70 to 85°F (21
6.11.4 Divide the net weight obtained in 6.11.3 by G.
to 29°C) and 45 to 55 % relative humidity.
Record as V, volume of patty.
7.6 Report:
Dry weight 2 Support plate tare weight
7.6.1 Report the type and amount of cracking in both the
V 5
G
thick half and the thin half of the wedge.
6.11.5 Subtract the immersed patty weight obtained in 7.7 Precision and Bias:
6.10.4 from the air patty weight obtained in 6.10.3. Record as 7.7.1 Precision and bias of this test method have not been
D, the weight difference. determined.
6.11.6 Calculate the percent shrinkage as follows:
8. Putrefaction
% Shrinkage 5 D~X/V!,
8.1 Significance and Use:
where:
8.1.1 This test method is used to evaluate the tendency of
D 5 the difference in air and immersed weight,
the joint compound to putrefy. The degree of correlation
X 5 100/displacement fluids specific gravity, and
between this test and service performance has not been
V 5 weight of wet patty/specific gravity of the compound.
determined.
8.2 Sampling:
6.12 Report:
8.2.1 Sampling shall be in accordance with Specification
6.12.1 Take the average of the three patties tested. If there is
C 475.
a difference between the percent shrinkage of the three patties
8.3 Apparatus:
of more than 1.5 %, completely retest an additional three
8.3.1 Humidity Cabinet, a chamber capable of maintaining
specimens and take the average of the six.
85 to 95°F (29 to 35°C) and 85 to 95 % relative humidity.
6.13 Precision and Bias:
...