For the past few years I have talked about many different aspects of art, particularly about genre or materials. I have written about paper being acid free so that the work of art will be archival quality. But then I started thinking about lightfastness.
Lightfastness is the way a pigment or color reacts when exposed to light, particularly sunlight. Pigment largely comes from stone and gems. The chemical makeup will decide whether a color is lightfast or not. That, and the vehicle or medium the artist uses such as oil, acrylic, watercolor, colored pencil, and so on.
The reason artists care about this is you. Let’s say you were fortunate to inherit a beautiful portrait of your grandmother in her young adult life. You’ve never actually beheld this beauty, but you remember the many stories of her wonderful dark auburn hair and piercing blue eyes. When you finally get to view this timeless piece of art, you discover that time came and went! Her once auburn hair is now blah brown! The blush of her cheeks is ashen. Her moist lips are dried up and vanished.
The reds in the painting were not lightfast! As artists, we know that our artwork has a life expectancy, based on the lightfastness of the pigments we use.
There is a worldwide standard for performance for lightfastness. Formed in 1984, ASTM (American Society for Testing and Materials) established these ratings and standards for artists’ materials. On the packaging of each individual medium we use, it will list “ASTM I – Excellent Lightfastness; ASTM II – Very Good Lightfastness; or ASTM III – Not Sufficiently Lightfast to use in artist paint.” Nowadays, we should be able to use ASTM I in almost all cases. The ASTM also lists things like opacity, transparency and health risks for the artist.
A word of caution. Student-grade art materials are not rated; check your materials. As artists, it is our responsibility to make certain that the media we use is as lightfast as possible; especially if we sell our work. Our integrity depends on it!
With Susan, there’s always something new under the sun!