“Transparent golden yellow. When used thickly it has an orange color like pumpkin custard.” From Just Paint: “a type of Diarylide Yellow, comes in various forms that all share the same Color Index Name of PY 83. As you can imagine, this can lead to some confusion when assigning a rating. The opaque version, which carries the additional designation ‘HR-70’ in its chemical description, has excellent lightfastness and is on the ASTM list of rated pigments. However, our testing showed that the Transparent version Williamsburg had chosen could only be rated as Fair, or the equivalent to ASTM III. And here lies the crux of our quandary. These three colors [Alizarin Yellow, Alizarin Orange, and Indian Yellow] have had exceptionally long and beloved histories within the Williamsburg brand, going back to its earliest days. Many painters who have used Williamsburg throughout these decades are passionately connected to their uniqueness, so a sudden change would be felt as particularly disruptive. And as if to confirm that, when searching for an alternative pigment we could use, we simply could not find anything with the same brilliance, transparency, and glow. So a choice needed to be made: dramatically change the look of these colors, discontinue them, or keep them as part of our offerings but clearly label their lighfastness as Fair, a rating similar to Alizarin Crimson.” -Williamsburg