Luminance 6901 was developed over the course of two years by Eric Vitus and the research and development team at Caran d'Ache. It has the same lightfastness as a high grade oil paint. The Luminance 6901 pencils conform to ASTM D-6901. 80% of these pencils are rated LF1 and 20% are rated LF2. This level of lightfastness was achieved by using the finest pigments and four synthetic waxes (30%).These waxes are added early in the pasteurization process to achieve perfect blending with the pigment mixture. This process inhibits waxy blooming in final pencils. The texture of Luminance 6901 is very uniform from one color to another with an 8B hardness.