ASTM D281-95

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Designation: D 281 – 95
AMERICAN SOCIETY FOR TESTING AND MATERIALS
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Oil Absorption of Pigments by Spatula Rub-out
This standard is issued under the fixed designation D 281; 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 5.2 Dropping Bottle, fitted with ground-in pipet and rubber
bulb or buret, graduated in 0.1-mL divisions.
1.1 This test method covers the determination of the oil
5.3 Smooth Glass Rub-up Plate or Marble Slab (glass
absorption of pigments by the spatula rub-out technique.
should have a surface similar to Hoover Muller Plates).
1.2 The values stated in SI units are to be regarded as the
5.4 Spatula, sharp-edged, steel, having a blade of 15 or 20
standard. The values given in parentheses are for information
1 3
mm by 100 mm ( ⁄2 or ⁄4 by 4 in.).
only.
5.5 Oil, linseed, raw, conforming to Specification D 234
1.3 This standard does not purport to address all of the
except that it shall have an acid number of 3 6 1. Linseed oil
safety concerns, if any, associated with its use. It is the
used in comparative tests must have the same acid value. Other
responsibility of the user of this standard to establish appro-
liquids, such as refined oil, may be used by mutual agreement.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
6. Procedure
2. Referenced Documents 6.1 Procedure A (Weighing Bottle)—Weigh exactly 1 g., or
any multiple thereof (Note 1), of the thoroughly mixed and air
2.1 ASTM Standards:
dried pigment and place upon a glass plate or marble slab.
D 234 Specification for Raw Linseed Oil
Weigh to 0.01 g a dropping bottle containing raw linseed oil
D 1483 Test Method for Oil Absorption of Pigments by
along with the pipet and rubber bulb. Add the linseed oil
Gardner-Coleman Method
gradually, drop by drop (by means of the pipet), to the pigment.
3. Summary of Test Method After the addition of each drop, thoroughly incorporate the oil
by rubbing up with the spatula. The test is complete when
3.1 A stiff, putty-like paste is formed by the dropwise
exactly enough oil has been incorporated with the pigment to
addition of linseed oil to pigment that is being thoroughly
produce a very stiff, putty-like paste, that does not break or
rubbed with a spatula. The amount of oil required to produce
separate. Weigh the bottle and oil to 0.01 g and determine by
the end point is used to calculate an oil absorption value.
difference the weight of oil used.
4. Significance and Use
NOTE 1—The specimen weight depends upon the specific gravity,
4.1 The oil absorption value obtained by this test method
fineness, and other characteristics of the pigment. For example, 20 g is
gives information about the vehicle demand of the pigment taken for white lead, but about1gissufficient for carbon black. In any
event, the specimen size should be large enough so that at least1gofoil
when it is used in a pigment paste. Oil absorption values can be
is required.
used to characterize pigments or batches of a given pigment.
4.2 This test method differs from Test Method D 1483 in
6.2 Procedure B (Buret):
that D 1483 involves only a gentle stirring and foldi
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