ASTM D2448-85(2007)
(Test Method)Standard Test Method for Water-Soluble Salts in Pigments by Measuring the Specific Resistance of the Leachate of the Pigment
Standard Test Method for Water-Soluble Salts in Pigments by Measuring the Specific Resistance of the Leachate of the Pigment
SIGNIFICANCE AND USE
This test method provides a reliable means for the determination of the relative amounts of these salts when comparing different lots of the same pigment grade. Water-soluble salts also affect the water resistance and blister resistance of coatings, especially primers for steel. Conductivity measurements, however, cannot be used as the only method to determine and compare the amount of water soluble salts of pigments with the same chemical composition but produced by different manufacturing processes.
SCOPE
1.1 This test method covers the determination of the specific resistance of the aqueous leachate from a pigment as an index of water-soluble salt content. This test method is applicable to white pigments and colored pigments (organic and inorganic). The water-soluble salts content is a function of the specific resistance of the solution formed by extracting the pigment with water.
1.2 This test method is based on a water to pigment ratio of 9+1. The leachate yield (minimum 160 mL) sufficient for rinsing the cylinder dip cell and thermometer plus the minimum 80 mL required for the measurement to determine the quantity of pigment to be used.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D2448 −85(Reapproved2007)
StandardTest 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 D2448; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 Thistestmethodcoversthedeterminationofthespecific 4.1 This test method provides a reliable means for the
resistance of the aqueous leachate from a pigment as an index determination of the relative amounts of these salts when
of water-soluble salt content. This test method is applicable to comparing different lots of the same pigment grade. Water-
white pigments and colored pigments (organic and inorganic). soluble salts also affect the water resistance and blister resis-
The water-soluble salts content is a function of the specific tance of coatings, especially primers for steel. Conductivity
resistance of the solution formed by extracting the pigment measurements, however, cannot be used as the only method to
with water. determine and compare the amount of water soluble salts of
pigments with the same chemical composition but produced by
1.2 This test method is based on a water to pigment ratio of
different manufacturing processes.
9+1. The leachate yield (minimum 160 mL) sufficient for
rinsing the cylinder dip cell and thermometer plus the mini-
5. Apparatus
mum 80 mL required for the measurement to determine the
5.1 Centrifuge (optional), having a 500-mL capacity per
quantity of pigment to be used.
cup.
1.3 The values stated in SI units are to be regarded as
5.2 Filter Paper (Note 1)—For high reliability avoid use of
standard. No other units of measurement are included in this
filter paper containing soluble material. Each filter should be
standard.
washed with reagent water in the funnel until resistance of the
1.4 This standard does not purport to address all of the
filtrate is greater than 200 000Ω · cm.
safety concerns, if any, associated with its use. It is the
NOTE 1—The size of the filter paper will be determined by how
responsibility of the user of this standard to establish appro-
voluminous the pigment is. Some organic pigments require at least a
priate safety and health practices and determine the applica-
185-mm paper for proper filtering.
bility of regulatory limitations prior to use.
5.3 Filter Aid (optional)—The use of a filter aid may be
desirable with some pigments to improve filtration. However,
2. Referenced Documents
the filter aid must be treated to meet the same specifications for
2.1 ASTM Standards:
filter paper as given in 5.2.
D1193 Specification for Reagent Water
5.4 Ungraduated Cylinders, approximately 35 mm wide by
3. Summary of Test Method
125 mm deep.
3.1 A weighed quantity of pigment is added to water and 5.5 Thermometer, graduated in 0.2°C intervals.
boiled. For hydrophobic pigments methyl alcohol is used to 3
5.6 Conductivity Bridge.
facilitate wetting. After filtration, the specific resistance of the
5.7 Conductivity Cell, having a cell constant, K,of1.The
filtrate is determined using a conductivity bridge.
cell constant recommended for various ranges of electrolytes is
as follows:
5.7.1 For specific resistances of less than 250Ω· cm, use a
This test method is under the jurisdiction of ASTM Committee D01 on Paint
cell with a constant of 10 or more.
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.31 on Pigment Specifications.
5.7.2 For specific resistances from 250 to 200 000Ω· cm,
Current edition approved June 1, 2007. Published June 2007. Originally
use a cell with a constant of 1. This covers the range for most
approved in 1966. Last previous edition approved in 2002 as D2448 – 85 (2002).
pigments.
DOI: 10.1520/D2448-85R07.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Any commercially produced conductivity bridge and conductivity cell is
the ASTM website. satisfactory.
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D2448−85(Reapproved2007)
TABLE 1 Specific Resistances of Solutions of Potassium
5.7.3 For specific resistances of reagent water or of over
Chloride at 25°C
200 000Ω · cm, use a cell with a constant of 0.1.
Normality Ω·cm
6. Reagents
0.001 6802 (1)
0.002 3427 (1)
6.1 Purity of Reagents—Reagent grade chemicals shall be
0.005 1393 (1)
used in all tests. Unless otherwise indicated, it is intended that
0.01 707.3 (1,2)
0.02 361.5 (3)
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
sufficiently high purity to permit its use without lessening the
8.2 Hydrophilic Pigments:
accuracy of the determination.
8.2.1 A 20.0-g specimen weight is usually sufficient for
6.2 Purity of Water—Unless otherwise indicated, references
pigments easily wet with water. Add 20.0 g of the pigment to
to water shall be understood to mean reagent grade water as
180 g of boiling water in a tared, 400-mL beaker with stirring
defined by Type II of Specification D1193.
rod. (Usually a 250-mLbeaker is sufficient for white pigments.
6.3 Methanol. Some white pigment, because of tendency to foam and crawl,
can be handled better in a larger beaker. Usually 20-g speci-
6.4 Potassium Chloride, Standard Solution (0.02 N)— Pre-
mens of organic pigments require a 600-mL beaker to allow
pare a 0.02 N potassium chloride (KCl) solut
...
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