The Lightfastness Ratings included in this chart are provided by the American Society for Testing and Materials (ASTM) in the standard for "Artists' Acrylic Emulsion Paints". (ASTM D 5098, Annual Book of Standards, Volume 6.02). Colors with a Lightfastness Rating of I are considered Excellent ("Exc.") and those with a Lightfastness Rating of II are Very Good ("V.G."). Where Lightfastness Ratings have not been obtained according to ASTM test protocol, "NA" is indicated in the table. In these cases, data from pigment manufacturers and our own test facilities have been used and an appropriate description assigned under Permanency.
For Opacity/Transparency, we have determined that an eight-point scale is most appropriate for describing the properties of our colors. We have assigned each color in the chart a number from 1 (most opaque) to 8 (most transparent) to indicate the relative opacity/transparency of that color.
The C.I. (Colour Index) Name is an internationally recognized code assigned to a particular "colorant." The C.I. Name consists of the category (type of dye or pigment), general hue and serial number assigned, based on its chemical constitution. For example, PB 60, Anthraquinone Blue, indicates a specific Pigment Blue. The C.I. Number is a five-digit reference number assigned in the Colour Index based on the chemical structure of a colorant, regardless of usage class.