ASTM D2448-85(1996)e1

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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e1
Designation: D 2448 – 85 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Water-Soluble Salts in Pigments by Measuring the Specific
Resistance of the Leachate of the Pigment
This standard is issued under the fixed designation D 2448; 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.
e NOTE—Keywords were added editorially in May 1996.
1. Scope determine and compare the amount of water soluble salts of
pigments with the same chemical composition but produced by
1.1 This test method covers the determination of the specific
different manufacturing processes.
resistance of the aqueous leachate from a pigment as an index
of water-soluble salt content. This test method is applicable to
5. Apparatus
white pigments and colored pigments (organic and inorganic).
5.1 Centrifuge (optional), having a 500-mL capacity per
The water-soluble salts content is a function of the specific
cup.
resistance of the solution formed by extracting the pigment
5.2 Filter Paper (Note 1)—For high reliability avoid use of
with water.
filter paper containing soluble material. Each filter should be
1.2 This test method is based on a water to pigment ratio of
washed with reagent water in the funnel until resistance of the
9+1. The leachate yield (minimum 160 mL) sufficient for
filtrate is greater than 200 000 V · cm.
rinsing the cylinder dip cell and thermometer plus the mini-
mum 80 mL required for the measurement to determine the
NOTE 1—The size of the filter paper will be determined by how
quantity of pigment to be used. voluminous the pigment is. Some organic pigments require at least a
185-mm paper for proper filtering.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5.3 Filter Aid (optional)—The use of a filter aid may be
responsibility of the user of this standard to establish appro-
desirable with some pigments to improve filtration. However,
priate safety and health practices and determine the applica-
the filter aid must be treated to meet the same specifications for
bility of regulatory limitations prior to use.
filter paper as given in 5.2.
5.4 Ungraduated Cylinders, approximately 35 mm wide by
2. Referenced Documents
125 mm deep.
2.1 ASTM Standards:
5.5 Thermometer, graduated in 0.2°C intervals.
D 1193 Specification for Reagent Water
5.6 Conductivity Bridge.
5.7 Conductivity Cell, having a cell constant, K,of1. The
3. Summary of Test Method
cell constant recommended for various ranges of electrolytes is
3.1 A weighed quantity of pigment is added to water and
as follows:
boiled. For hydrophobic pigments methyl alcohol is used to
5.7.1 For specific resistances of less than 250 V· cm, use a
facilitate wetting. After filtration, the specific resistance of the
cell with a constant of 10 or more.
filtrate is determined using a conductivity bridge.
5.7.2 For specific resistances from 250 to 200 000 V· cm,
use a cell with a constant of 1. This covers the range for most
4. Significance and Use
pigments.
4.1 This test method provides a reliable means for the
5.7.3 For specific resistances of reagent water or of over
determination of the relative amounts of these salts when
200 000 V · cm, use a cell with a constant of 0.1.
comparing different lots of the same pigment grade. Water-
soluble salts also affect the water resistance and blister resis- 6. Reagents
tance of coatings, especially primers for steel. Conductivity
6.1 Purity of Reagents—Reagent grade chemicals shall be
measurements, however, cannot be used as the only method to
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
tee on Analytical Reagents of the American Chemical Society,
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.31 on Pigment Specifications.
Current edition approved Nov. 29, 1985. Published January 1986. Originally
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published as D 2448 – 66 T. Last previous edition D 2448 – 73 (1979) . Any commercially produced conductivity bridge and conductivity cell is
Annual Book of ASTM Standards, Vol 11.01. satisfactory.
D 2448
TABLE 1 Specific Resistances of Solutions of Potassium
where such specifications are available. Other grades may be
Chloride at 25°C
used, provided it is first ascertained that the reagent is of
Normality V ·cm
sufficiently high purity to permit its use without lessening the
0.001 6802 (1)
accuracy of the determination.
0.002 3427 (1)
6.2 Purity of Water—Unless otherwise indicated, references
0.005 1393 (1)
to water shall be understood to mean reagent grade water as
0.01 707.3 (1,2)
defined by Type II of Specification D 1193. 0.02 361.5 (3)
6.3 Methanol.
6.4 Potassium Chloride, Standard Solution (0.02 N)— Pre-
pare a 0.02 N potassium chloride (KCl) solution with water by
occasional stirring. Cool to about 60°C and add water to bring
dissolving 1.491 g of KCl (heated before weighing for1hat
the net weight back to 200 g. Stir thoroughly. Filter directly
105°C) in water, followed by dilution to 1 L.
through fine-texture paper (Note 1) or separate the solids by
centrifuge using clean, dry cups, or cups washed
...