ASTM stands for the American Society for Testing and Materials.
D6901 is the Standard Specification for Artists' Colored Pencils.
This specific standard was developed by ASTM International with assistance from the Colored Pencil Society of America (CPSA) and pencil manufacturers.
It establishes requirements for colored pencil formula, performance, labeling, and lightfastness and is considered the gold standard for testing.
ASTM lightfastness testing uses both natural daylight and artificial xenon-arc light to evaluate how well individual colors resist fading or change over time.
Pencils receive lightfastness ratings from I (very lightfast) to V (fugitive).
Only pencils rated I or II meet the standard's lightfastness requirements, rated to last from 50 to 100+ years before fade or change occurs. Pencils in groups I and II are those considered lightfast enough for ethical sales of original art.
Compliance is voluntary. Many companies use the Blue Wool method which predates ASTM Standards while other companies invent their own standards and tests.
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And if you’ve ever wondered why Caran d’Ache Luminance pencils are marked “Luminance 6901”, now you know.
