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.