ASTM D4890-98
(Test Method)Standard Test Methods for Polyurethane Raw Materials Determination of Gardner and APHA Color of Polyols
Standard Test Methods for Polyurethane Raw Materials Determination of Gardner and APHA Color of Polyols
SCOPE
1.1 These test methods measure visually the color of clear polyester and polyether liquids. They apply only to materials whose colors have light-absorption characteristics similar to those of the standards. An alternative method is Test Method D1209. (See Note 1.)
1.2 This standard does not purport to address all of the safety problems, 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. Note 1-There is no equivalent ISO standard.
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Designation: D 4890 – 98
Standard Test Methods for
Polyurethane Raw Materials: Determination of Gardner and
APHA Color of Polyols
This standard is issued under the fixed designation D 4890; 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 Estimation of Color of Clear Liquids by the Color Scale
ISO 6271-1981 Clear Liquids—Estimation of Color by the
1.1 These test methods measure visually the color of clear
Platinum-Cobalt Scale
polyester and polyether liquids. They apply only to materials
whose colors have light-absorption characteristics similar to
3. Terminology
those of the standards. An alternative method is Test Method
3.1 For definitions of terms used in these test methods see
D 1209. (See Note 1.)
Terminology D 883.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
4.1 In Test Method A, the color of the material to be tested
priate safety and health practices and determine the applica-
is compared to a series of color standards with defined
bility of regulatory limitations prior to use.
chromicity coordinates, prepared on one of three ways. The
NOTE 1—Although Test Method A of these test methods and ISO 4630-
results are reported as the color standard, which best matches
1997 differ in some details, data obtained using either are technically
the sample.
equivalent. Although Test Method B of these test methods and ISO 6271-
4.2 In Test Method B, the color of the material to be tested
1981 differ in some details, data obtained using either are technically
is compared to a series of platinum-cobalt color standards,
equivalent.
designated by mg of Pt/mL of standard solution. The results are
2. Referenced Documents
reported as the color standard, which best matches the sample
(Note 2).
2.1 ASTM Standards:
D 883 Terminology Relating to Plastics
NOTE 2—Color of liquids also can be measured by visible spectroscopy
D 1193 Specification for Reagent Water
and the results converted to any of several color scales. These results can
D 1209 Test Method for Color of Clear Liquids (Platinum- be converted to the APHA scale by appropriate manipulations, as for
example in Test Method D 5386.
Cobalt Scale)
D 5386 Test Method for Color of Liquids Using Tristimulus
5. Significance and Use
Colorimetry
5.1 These test methods are suitable for quality control, as
E 308 Practice for Computing the Colors of Objects by
specification tests, and for research. Color is an important
Using the CIE System
property of urethane products.
E 1164 Practice for Obtaining Spectrophotometric Data for
Object-Color Evaluation
6. Sampling
2.2 ISO Standards:
6.1 Polyesters and polyethers usually contain molecules
ISO 4630-1997 Binders for Paints and Varnishes—
covering an appreciable range of molecular weights. These
have a tendency to fractionate during solidification. Unless the
material is a liquid or finely ground solid it is necessary to melt
(using no higher temperature than necessary) and mix the resin
These test methods are under the jurisdiction of Committee D-20 on Plastics
well before removing a sample for analysis. Many polyols are
and are the direct responsibility of Subcommittee D20.22 on Cellular Plastics.
hygroscopic and care should be taken to provide minimum
Current edition approved July 10, 1998. Published January 1999. Originally
published as D 4890 – 88. Last previous edition D 4890 – 93. exposure to atmospheric moisture during the sampling.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 11.01.
4 6
Annual Book of ASTM Standards, Vol 06.04. Available from American National Standards Institute, 11 W. 42nd St., 13th
Annual Book of ASTM Standards, Vol 14.02. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4890
7. Purity of Reagents 9.2 Ferric Chloride Solution—Prepare a solution containing
approximately 5 parts by weight of ferric chloride
7.1 Purity of Reagents—Reagent-grade chemicals shall be
(FeCl 3 6H O) and 1.2 parts of HCl (1 to 17). Adjust to exact
used in all tests. Unless otherwise indicated, it is intended that 3 2
color equivalence to a freshly prepared solution containing 3 g
all reagents shall conform to the specifications of the Commit-
of K Cr O in 100 mL of H SO (sp gr 1.84).
2 2 7 2 4
tee on Analytical Reagents of the American Chemical Society,
9.3 Hydrochloric Acid (1 to 17)—Mix 1 volume of concen-
where such specifications are available. Other grades may be
trated hydrochloric acid (HCl, sp gr 1.19) with 17 volumes of
used, provided it is first ascertained that the reagent is of
water.
sufficiently high purity to permit its use without lessening the
9.4 Hydrochloric Acid (0.1 N)—Prepare 0.1 N HCl.
accuracy of the determination.
9.5 Potassium Chloroplatinate (K Cr O ).
2 2 7
7.2 Purity of Water—Unless otherwise indicated, references
9.6 Potassium Dichromate (K Cr O ).
2 2 7
to water shall be understood to mean reagent water as defined
9.7 Sulfuric Acid (sp gr 1.84)—Concentrated sulfuric acid
by Type IV or better of Specification D 1193.
(H SO ).
2 4
TEST METHOD A—GARDNER COLOR
10. Gardner Color Reference Standards
8. Apparatus 10.1 The primary standards for color shall consist of solu-
tions defined by their spectral transmittance in 1-cm cell with
8.1 Gardner-Holdt Tubes, of clear glass, with closed, flat,
parallel sides. The chromaticity coordinates of these solutions
even bottoms, and having the following approximate dimen-
shall conform to those given in Table 1 when determined on a
sions and markings:
1-cm layer of the solution in accordance with Practice E 1164
8.1.1 A uniform internal length of 112 mm,
and Test Method E 308.
8.1.2 A uniform internal diameter throughout the length of
10.2 For comparison, permanent solutions of known color
the tube of 10.75 mm, and
are more satisfactory. The approximate composition of solu-
8.1.3 An etched line around the outside of the tube 5 mm
tions giving each of the 18 Gardner colors is also given in
from the open end and a second etched line around the outside
Table 1. The solutions shall be made from K PtCl in 0.1 N
2 6
of the tube 13 mm from the open end.
HCl, or, in the darker colors, from stock solutions of FeCl ,
CoCl , and HCl (9.1, 9.2, and 9.3).
9. Reagents
10.3 Solutions of K Cr O (sp gr 1.84) may be used as
2 2 7
9.1 Cobalt Chloride Solution—Prepare a solution contain-
reference standards. The approximate composition of these
ing 1 part by weight of cobalt chloride (CoCl 3 6H O) to 3
2 2
standards is also given in Table 1. Each solution must be
parts of HCl (1 to 17).
freshly made for the color comparison, using gentle heat, if
necessary, to effect solution.
10.4 Secondary reference standards may be obtained in the
Reagent Chemicals, American Chemical Society Specifications, American
form of 18 colored glass disks, which are set into a pair of
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Glass color standards and color standard solutions are available from BYK-
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Gardner USA, 2435 Linden Lane, Silver Spring, MD 20910.
MD.
TABLE 1 Gardner Reference Standard Color Solutions
Chromaticity
Iron-Cobalt Solutions
A
Potassium
Coordinates
Gardner Color Standard Potassium Dichromate,
Chloroplatinate, g/1000
B
Number g/100 mL Sulfuric Acid
Ferric Chloride Cobalt Chloride
mL of 0.1 NHCl
xy Hydrochloric Acid, mL
Solution, mL Solution, mL
1 0.3190 0.3271 0.550 . . . . . . . . . 0.0039
2 0.3241 0.3344 0.865 . . . . .
...
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