ASTM C609

1.1 This test method covers the measurement of Light Reflectance Value (LRV) and visually small color difference between pieces of glazed or unglazed ceramic tile, using any spectrophotometer that meets the requirements specified in the test method. LRV and the magnitude and direction of the color difference are expressed numerically, with sufficient accuracy for use in product specification.

1.2 LRV may be measured for either solid-colored tile or tile having a multicolored, speckled, or textured surface. For tile that are not solid-colored, an average reading should be obtained from multiple measurements taken in a pattern representative of the overall sample as described in 9.2 of this test method. Small color difference between tiles should only be measured for solid-color tiles. Small color difference between tile that have a multicolored, speckled, or textured surface, are not valid.

1.3 For solid colored tile, a comparison of the test specimen and reference specimen should be made under incandescent, fluorescent and daylight illuminant conditions. The use of multiple illuminants allows the color difference measurement to be made without the risk of wrongly accepting a match when the tiles being compared are metamers. (See 3.1.4.)

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

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

Index Terms

color differences; color equations; color measurement; glaze color; light reflectance; tristimulus; ICS Number Code 91.100.25 (Terracotta building products)

Citing ASTM Standards

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