1. Scope

1.1 This test method covers the measurement of a visually small color difference between two pieces of solid-colored, glazed or unglazed ceramic tile, using any photoelectric instrument that meets the requirements specified in the test method. The amount and the direction of the color difference are expressed numerically, with sufficient accuracy for use in product specification.

1.2 This test method should not be used for determining small color differences between tile that have a multicolored, speckled, or textured surface, because the results may not be valid.

1.3 Color difference between specimens found to be metamers (see 3.2), by visual examination, can be accurately evaluated by spectrophotometric measurement only. Therefore, visual color comparison of test specimen and reference specimen should be made under incandescent light and under daylight fluorescent light before any instrumental measurement. If visual color difference under the two light sources is not of the same magnitude, the pair of tile must be considered metamers.

1.4 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.5 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.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

C242 Terminology of Ceramic Whitewares and Related Products

D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates

E259 Practice for Preparation of Pressed Powder White Reflectance Factor Transfer Standards for Hemispherical and Bi-Directional Geometries

E284 Terminology of Appearance

Keywords

color differences; color equations; color measurement; glaze color; light reflectance; tristimulus;

ICS Code

ICS Number Code 91.100.25 (Terracotta building products)

DOI: 10.1520/C0609-90R00

ASTM International is a member of CrossRef.