ASTM E2808-11

Paint sample colors can be measured by reflectance (visible range) or transmission (UV-Vis) for comparison purposes. Transmission measurements are especially necessary for the analysis of UV absorbers in clear coats, the identification of pigments, and the detailed analysis of effect pigments that are not opaque.

This guide is designed to assist an analyst in the selection of appropriate sample preparation methods and instrumental parameters for the analysis, comparison, or identification of paint pigments and colors.

It is not the intention of this guide to present comprehensive theories and methods of MSP. It is necessary that the analyst have an understanding of UV-VIS MSP and general concepts of specimen preparation before using this guide. This information is available from manufacturers’ reference materials, training courses, and references such as “Visible Microscopical Spectrophotometry in the Forensic Sciences” and “The Role of Colour and Microscopic Techniques for the Characterisation of Paint Fragments.”

1.1 This guide is intended to assist individuals and laboratories that conduct forensic visible and ultraviolet (UV) spectral analyses on small fragments of paint using Guide E1610.

1.2 This guide deals primarily with color measurements within the visible spectral range but will also include some details concerning measurements in the UV range.

1.3 This guide does not address other areas of color evaluation such as paint surface texture or paint pigment particle size, shape, or dispersion within a paint film that are evaluated by other forms of microscopy. Other techniques such as spectral luminescence, fluorescence, and near infrared (NIR) are not included in this guide because of their limited use, lack of validation, or established efficacy in forensic paint analysis.

1.4 This guide is directed at the color analysis of commercially prepared paints and coatings. It does not address the analysis or determination of provenance of artistic, historical, or restorative paints, but it may be found useful in those fields.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 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.