The most direct and accessible methods for obtaining the color coordinates of ceramic glazes and related whitewares are by instrumental measurement using spectrophotometers or colorimeters with either hemispherical or bidirectional optical measuring systems. This test method provides procedures for such measurement by reflectance spectrophotometry using a hemispherical optical measuring system.

This test method is especially suitable for measurement of the following types of specimens for the indicated uses(See Practice E805.):

All types of ceramic glaze and related whiteware specimens to obtain data for use in computer colorant formulation.

Ceramic glaze and related whiteware specimens for color assessment.

For the measurement of plane-surface high-gloss specimens, the specular component should generally be excluded during the measurement.

For the measurement of plane-surface intermediate-gloss (satin) specimens, where the first-surface reflection component may be distributed over a wide range of angles, measurement may be made with the specular component included, but the resulting color coordinates may not correlate best with visual judgments of the color. Measurement with specular excluded may lead to better correlations.

For the measurement of plane-surface, low-gloss (matte) specimens, the specular component may either be excluded or included, as no significant difference in the results should be apparent.

An estimate of gloss may be obtained by measuring the reflection both with the specular component of reflection included and excluded, and then calculating the difference between the two measurements at several wavelengths across the visible spectrum, as described in 10.2.

1. Scope

1.1 This test method describes the instrumental measurement of the reflection properties and color of ceramic glazes and other whitewares by the use of a spectrophotometer or spectrocolorimeter with a hemispherical optical measuring system, such as an integrating sphere.

1.2 The test method is suitable for use with most specimens having an exterior flat surface large enough to cover the spectrophotometer sample port.

1.3 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

E179 Guide for Selection of Geometric Conditions for Measurement of Reflection and Transmission Properties of Materials

E284 Terminology of Appearance

E308 Practice for Computing the Colors of Objects by Using the CIE System

E805 Practice for Identification of Instrumental Methods of Color or Color-Difference Measurement of Materials

E1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation

E1331 Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry

Keywords

color; hemispherical geometry; reflectance; reflectance factor; spectrophotometry; Ceramic whitewares; Color--ceramic materials/applications; Abridged spectrophotometry method; Comparison techniques; Hemispherical geometry; Reflectance factor; Spectrophotometry

ICS Code

ICS Number Code 71.040.50 (Physicochemical methods of analysis)

Citing ASTM Standards

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