ASTM E2937-26

1.1 Infrared (IR) spectroscopy is a valuable method for the identification and comparison of paints and coatings (1-11). This guide provides basic recommendations and information about infrared spectrometers and accessories, with an emphasis on sampling techniques specific to paint and coatings examinations. The particular method(s) employed by each practitioner or laboratory will depend upon available equipment, practitioner training, sample size or suitability, and purpose of examination.

1.2 This guide is to be used in conjunction with a broader analytical scheme such as Guide E1610.

1.3 This guide is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practices E2917 and E3234) and demonstrated proficiency to perform forensic casework.

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

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

5.1 This guide is designed to assist a practitioner in the selection of appropriate sample preparation methods for the analysis, comparison, and classification of paints.

5.2 It is not the intent of this guide to present comprehensive theories and methods of IR spectroscopy. It is necessary that the practitioner has an understanding of IR spectroscopy and general concepts of sample preparation prior to using this guide. This information is available from manufacturers’ reference materials, training courses, and references such as: “Infrared Microspectroscopy of Forensic Paint Evidence” (4), “Use of infrared spectroscopy for the characterization of paint fragments” (5), “Forensic applications of infrared spectroscopy” (3), and An Infrared Spectroscopy Atlas for the Coatings Industry (1).

5.3 Infrared spectroscopy can provide chemical information regarding major organic and inorganic components of paints, which include binders, fillers, and pigments.

5.4 Infrared spectroscopy can also be employed for the comparison of two or more paint samples. When used for spectral comparisons, the objective is to determine whether any exclusionary differences exist between the samples.