About Lightfast Ratings
I use the ASTM lightfast ratings from Mark Gottsegen's book, The Painter's Handbook. They are as follows:
- 8 Excellent lightfastness.
- 7 Very good lightfastness.
- 6 Very good lightfastness
- 5/4 Fair lightfastness (Impermanent).
These ratings are based off the pigment ratings themselves and not off of the paint. A variety of factors can impact the lightfastness of your paint including how thinly you choose to apply the color. A good rule is if your watercolors are going to be displayed they should be behind UV protectant glass OR sealed against UV damage.
About Pigment Numbers
For my colors I have provided the base pigment numbers (or simple chemical name when there is no pigment number traditionally used). Please be aware that a single pigment number can create a wide array of colors depending upon the formulation and mixing. As such, they should be used as a starting point for understanding the formula for those of you who are interested.