ASTM E2539-08

This practice is designed to provide color data obtained from spectral reflectance factors at specific illumination and detection angles for interference pigments. Information presented in this test practice is based upon data taken on materials exclusively pigmented with interference pigments.

These data can be used for acceptance testing, design purposes, research, manufacturing control, and quality control.

Specimens must be statistically representative of the end use.

Applicability of this practice for other materials, including combining interference pigments with absorbing and scattering pigments should be confirmed by the user.

1.1 This practice covers the instrumental requirements and required parameters needed to make instrumental color measurements of thin film interference pigments. This practice is designed to encompass interference pigments used in architectural applications, automobiles, coatings, cosmetics, inks, packaging, paints, plastics, printing, security, and other applications.

1.2 Characterization of the optical behavior of materials colored with interference pigments requires measurement at multiple angles of illumination and detection.

1.3 Data taken utilizing this practice are quantitative and are appropriate for quality control of interference pigment color.

1.4 The measurement results are usually expressed as reflectance factors, tristimulus color values, or as CIE L*a*b* color coordinates and color difference.

1.5 The totality of data taken may not be necessary for evaluating mixtures also containing non-interference pigments. The committee is investigating and evaluating the appropriateness of this practice for those materials. It is the responsibility of the users to determine the applicability of this practice for their specific applications.

1.6 Interference pigments are typically evaluated for color and color appearance in a medium, such as paint or ink. The gonioapparent effect depends strongly on the physical and chemical properties of the medium. Some of the properties affecting color and color appearance include vehicle viscosity, thickness, transparency, and volume solids. As a general rule, for quality control purposes, interference pigments are best evaluated in a masstone product form. In some cases this product form may be the final product form, or more typically a qualified simulation of the intended product form (such as a paint drawdown) that in terms of color and appearance correlates to final product application.

1.7 This standard does not address the requirements for characterizing materials containing metal flake pigments. Measurements of the optical characteristics of materials containing metal flake pigments are described in Practice E 2194.

1.8 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.9 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.