Designation: D 6166 – 97

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

Color of Naval Stores and Related Products (Instrumental
Determination of Gardner Color)1
This standard is issued under the fixed designation D 6166; 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 from Gardner 1 to Gardner 18. The Gardner scale is not

1.1 This test method covers the quantitative determination applicable to materials with colors lighter than 1 or darker than
of the color of clear, yellow/brown, liquid materials using color 18.
measuring instruments. The results may be invalid if other
5. Apparatus
materials are used. The test uses the Gardner color scale
described in Test Method D 1544. This test method applies to 5.1 An instrument capable of measuring transmitted color
naval stores products including tall oil, tall oil fatty acids, and reporting the results in the Gardner color scale described in
rosin, and related products. Test Method D 1544. If such an instrument is not available, one
1.2 This standard does not purport to address all of the may be used which is capable of measuring transmitted color
safety concerns, if any, problems associated with its use. It is and reporting in tristimulus values or chromaticity coordinates
the responsibility of the user of this standard to establish using standard illuminant C and the 2° observer, described in
appropriate safety and health practices and determine the Practice E 308.
applicability of regulatory limitations prior to use. 5.2 Glass Cuvets, 10–mm path length, unless a different
path length is specified by the manufacturer, or
2. Referenced Documents 5.3 Glass Tubes, clear. Standard Gardner tubes, as described
2.1 ASTM Standards: in Test Method D 1544, or other glass tubes designed for a
D 1544 Test Method for Color of Transparent Liquids specific instrument may be used. Gardner tubes may provide
(Gardner Color Scale)2 less accuracy than glass cuvets and should be used only when
E 177 Practice for the Use of the Terms Precision and Bias a decrease in accuracy is acceptable. Glass cuvets should be
in ASTM Test Methods3 used for referee situations.
E 308 Practice for Computing the Colors of Objects by
6. Calibration and Standardization
Using the CIE System3
E 691 Practice for Conducting an Interlaboratory Study to 6.1 Calibrate the instrument following the manufacturer’s
Determine the Precision of a Test Method3 recommendations.

3. Summary of Test Method 7. Procedure

3.1 The color of a liquid sample is measured using an 7.1 Taking care not to touch the measurement area of the
instrument capable of measuring transmitted color and report- sample cell, fill a clean Gardner tube or cuvet with the material
ing in Gardner colors or in a color system that can be converted to be tested. If the material is cloudy, first filter it.
to Gardner colors. 7.2 Insert the glass tube or cuvet in the instrument and
measure the color, following the manufacturer’s recommended
4. Significance and Use procedure.
4.1 This test method provides a more precise way of 8. Report
measuring Gardner color than described in Test Method D
8.1 Report the color in Gardner color units to a tenth of a
1544. It is applicable to naval stores products having colors
Gardner unit as given by the instrument or as calculated by the
1
method in the appendix. Note if the material was filtered.
This test method is under the jurisdiction of Committee D-1 on Paint and
Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.34 on Naval Stores.
9. Precision and Bias
Current edition approved Aug. 10, 1997. Published October 1997.
2
9.1 Interlaboratory Test Program—An interlaboratory
Annual Book of ASTM Standards, Vol 06.01.
3 study of the color of three materials was run in 1996. Each of
Annual Book of ASTM Standards, Vol 14.02.
13 laboratories tested each of the three materials. The design of

1
 D 6166
the experiment, similar to that of Practice E 691 and a limit) are used as specified in Practice E 177. The respective
within-between analysis of the data are given in ASTM standard deviations among test results, related to the above
Research Report.4 numbers by the factor of 2.8, are as follows:
9.2 Test Result—The precision information given below for 9.3.1 Repeatability standard deviation 5 0.02 Gardner
Gardner color is for the comparison of three test results, each units.
of which is the average of three test determination as follows: 9.3.2 Reproducibility standard deviation 5 0.18 Gardner
9.2.1 Repeatability Limit, 95 % (within laboratory) 5 0.06 units.
Gardner units. 9.4 Bias—Since there is no accepted reference material
9.2.2 Reproducibility Limit, 95 % (between laboratories) 5 suitable for determining the bias for the procedures in this test
0.50 Gardner units. method, bias has not been determined.
9.3 These terms (repeatability limit and reproducibility
10. Keywords
4
Supporting data are available from ASTM Headquarters. Request 10.1 instrumental Gardner color; rosin; tall oil; tall oil fatty
RR:D01–1106. acids

APPENDIX

(Nonmandatory Information)

X1. CALCULATING GARDNER COLOR FROM CHROMATICITY COORDINATES

X1.1 For instruments reporting in tristimulus values or where:

chromaticity coordinates, measure the tristimulus values or GTM 5 the Gardner color of the test material,
chromaticity coordinates using 10–mm cuvets or standard GI 5 the integer portion of the test material’s Gardner
Gardner tubes. Sample cells with larger or smaller path lengths color value, and
will produce tristimulus values and chromaticity coordinates GF 5 the fractional portion of the Gardner color value.
that will not convert, using Table 1, to the true Gardner color
of the test material. X1.5 By comparing the x-chromaticity coordinate of the
test material with the x-chromaticity coordinate in Table 1 of
X1.2 Record the tristimulus values X, Y, Z, or the chroma- Test Method D 1544, determine the integer portion of the test
ticity coordinates x, y, Y for the test material. material’s Gardner color using the relationship as follows:
X1.3 If the instrument reports tristimulus values, convert GI 5 Gn, where: xn # xTM , xn11 (X1.2)
them to chromaticity coordinates using the procedure in where:
Practice E 308. Gn 5 the Gardner color value which is lighter than the
test material,
X1.4 The Gardner value of the test material is determined xn 5 the x chromaticity coordinate of the Gardner color
as follows: value which is lighter than the test material,
GTM 5 GI 1 GF (X1.1) xTM 5 the x chromaticity coordinate of the test material,
and
TABLE 1 Chromaticity Coordinates of Gardner ColorsA xn+1 5 the x chromaticity coordinate of the Gardner color
Gardner color x y Y
value which is darker than the test material.
1 0.3177 0.3303 80
2 0.3233 0.3352 79 X1.6 Calculate the fractional portion of the test material’s
3 0.3329 0.3452 76 Gardner color as follows:
4 0.3437 0.3644 75
5 0.3558 0.3840 74 ~xn11 –xn!~xTM – xn! 1 ~yn11 –yn!~yTM – yn!
GF 5 (X1.3)
6 0.3767 0.4061 71 ~xn11 – xn!2 1 ~yn11 – yn!2
7 0.4044 0.4352 67
8 0.4207 0.4498 64
9 0.4343 0.4640 61
where:
10 0.4503 0.4760 57 yn 5 the y chromaticity coordinate of the
11 0.4842 0.4818 45 Gardner color value which is lighter
12 0.5077 0.4638 36 than the test material,
13 0.5392 0.4458 30
14 0.5646 0.4270 22 yTM 5 the y chromaticity coordinate of the
15 0.5857 0.4089 16 test material, and
16 0.6047 0.3921 11 yn+1 5 the y chromaticity coordinate of the
17 0.6290 0.3701 6
18 0.6477 0.3521 4
Gardner color value which is darker
A than the test material.
See Test Method D 1544.

2
 D 6166

xn, xn+1, and xTM 5 definition of Eq X1.3. so

GF 5 0.7 (X1.5)
Example 1. For a test material with chromaticity coordinates
of xTM5 0.3685, yTM5 0.3998. From Table 1, xTM is between and
the chromaticity coordinates for Gardner color values 5 and 6, GTM 5 5.7.
therefore GI5 5 and
GF5
~0.3767 –0.3558!~0.3685 – 0.3558! 1 ~0.4061 – 0.3840!~0.3998 – 0.3840!
~0.3767 – 0.3558!2 1 ~0.4061 – 0.3840!2
(X1.4)

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