ASTM traditionally stands for America Society for Testing Materials - however it has become known to also mean American Standard Test Measure. Regardless, today it is an internationally recognized term used by many artists when referring to artists paint.

For artists an ASTM rating is invaluable when comparing different brands of artists paints, in particular when referring to pigments and their light fastness; the resistance to fading. A paint manufacturer may name a color whatever they desire regardless of it's quality of pigment, and when comparing names alone it can be confusing to know the quality or true source of the pigment.

ASTM standards divide pigments into 5 levels for light fastness: