Proposed ASTM standard, ASTM WK45240, Test Methods for the Particle Size Distribution Measurement of Powdered Materials by Wet and Dry Laser Diffraction, will set out general approach to measuring powders, suspensions, or slurries using appropriate wet or dry methodology. Standard will provide practical guidance on sampling, dispersion, verification, and correct use of optical constants. Applications include fuel injection, emulsions, perfumery, paints, coatings, and ceramic plates.