ASTM C59/C59M-00

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Designation: C 59/C 59M – 00
Standard Specification for
Gypsum Casting Plaster and Gypsum Molding Plaster
This standard is issued under the fixed designation C 59/C 59M; 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.
1. Scope * 4. Chemical Composition
1.1 This specification covers gypsum casting plaster and 4.1 Gypsum casting plaster and gypsum molding plaster
gypsum molding plaster materials consisting essentially of shall have a purity of not less than 85 % CaSO ·2H O when
4 2
calcined gypsum. tested in accordance with Test Methods C 471.
1.2 The values stated in either inch-pound or SI (metric)
5. Physical Properties
units are to be regarded as standard. Within the text, the SI
5.1 Specimens shall be tested in accordance with Test
units are shown in brackets. The values stated in each system
shall be used independently of the other. Values from the two Methods C 472.
5.1.1 Setting Time—Gypsum casting plaster and gypsum
systems shall not be combined.
1.3 The text of this standard references notes and footnotes molding plaster shall set in not less than 10 nor more than 50
min using the procedure for gypsum concrete and all gypsum
that provide explanatory material. These notes and footnotes
shall not be considered as requirements of the standard. plasters, except gypsum neat plaster.
5.1.2 Compressive Strength—Gypsum casting plaster and
2. Referenced Documents
gypsum molding plaster shall have a compressive strength of
2.1 ASTM Standards: not less than 1800 psi [12.4 MPa].
C 11 Terminology Relating to Gypsum and Related Build- 5.1.3 Fineness—Gypsum casting plaster and gypsum mold-
ing Materials and Systems ing plaster shall all pass a No. 30 [600-µm] sieve and not less
C 471 Test Methods for Chemical Analysis of Gypsum and than 90 % shall pass a No. 100 [150-µm] sieve.
Gypsum Products
6. Sampling
C 472 Test Methods for Physical Testing of Gypsum, Gyp-
6.1 Randomly select not less than 1 % of the packages, but
sum Plasters and Gypsum Concrete
E 11 Specification for Wire-Cloth and Sieves for Testing not less than 5 packages. Take samples of approximately equal
amounts both from the outer portion and the center of each
Purposes
package. Mix the samples so obtained to provide a composite
3. Terminology
sample of not less than 7 lb [3 kg]. Immediately place the
3.1 Definitions of terms shall be in accordance with Termi- composite sample in a clean, dry, airtight container for delivery
nology C 11. to the laboratory.
3.2 Description of Terms Specific to This Standard:
7. Inspection
3.2.1 gypsum casting plaster, n—a calcined gypsum plaster
7.1 Inspection of the gypsum casting and molding plaster
used primarily to form objects, such as lamp bases, art ware,
and novelties, etc. shall be agreed upon by the purchaser and the supplier as part
of the purchase agreement.
3.2.2 gypsum molding plaster, n—a calcined gypsum plaster
used primarily for plaster casts or molds, sometimes used as a
8. Rejection
gauging plaster.
8.1 Rejection of gypsum casting plaster and gypsum mold-
ing plaster
...