Lightfastness in general means the ability for a material to maintain its ability to resist fading when exposed to light. More specifically, the ultraviolet light spectrum produced by the sun and specific light fixtures. If you’ve ever had a piece of colored construction paper hung in your window and noticed when you moved it or took it down that the color had faded to a grayer tone, then that paper had poor lightfastness quality. Similar things happen to paint pigments, dyes, and inks when exposed to the sun. In this article, we will discuss how good lightfastness plays a role in maintaining the integrity of your artwork as well as some techniques you can use to amplify the lightfastness quality of what you’re working on.
For Nova Color specifically, this means the pigments ability to stay chromatic and bright is maintained when exposed to the light. Nova Color’s lightfastness ratings are made according to the American Society for Testing and Materials D5098 Test Methods for Lightfastness of Pigments used in Artists Paint:
I=Excellent
II=Very Good
III=Does not conform to ASTM D5098
When reviewing the ASTM D5098 Test Methods for Lightfastness of Pigments in Artist’s Paint, it should be noted that the specific methodology used to test for lightfastness is not listed and is behind a paywall. However, we can lend some credibility to the testing as the ASTM, formally known as the “American Society for Testing and Materials” is now an international standards organization that has been around for 125+ years. ASTM International is involved in the testing of many materials across various industries for safety and consumer confidence.
Also, based on the methods of other ASTM standards, such as “Blue Wool ASTM 5398” testing system, we can conclude that the methodology is consistent and widely used. The Blue wool testing system is for “art materials not conforming to specifications D4302, D5098 or D5067 and when it is not feasible to use Test Methods D4303.”, which sees the materials tested in comparison to varyingly dyed wool swatches. These differently dyed wools are a control method designed to fade under known amounts of exposure to ultraviolet light.
An educated guess is that specific instruments are being used to measure the pigment. As the ASTM 5098 highlights specific pigments and the associated lightfastness rating for said pigments. Likely, an instrument that measures the amount of generated UV light is used to compare each pigment to a well-established control.
Now, what do these ratings mean in practice for those who use Nova Color paints? First it means you do need to be a bit choosier about which paint you use when thinking about if your final paintings will be displayed outdoors or inside with reduced exposure to the sun.
122 Ultramarine Blue has a Lightfastness Rating of I
Many of our lightfastness I paints are commonly used in murals, which means that they get direct sun and exposure to the elements. We’ve seen some murals last 30+ years with our paints before needing repairs, such as the mural “Anthony Quinn or The Pope of Broadway” (1985).
186 Medium Violet has a Lightfastness Rating of II
Pigments that are lightfastness II are rated to last for 100 years under museum conditions. Which generally means the work is stored and displayed under temperature and humidity control with limited exposure to the sun.
198 Fluorescent Green has a Lightfastness Rating of III
Paintings made with Lightfastness III are usually paints that are not intended for longevity, but rather special use cases. For example, our fluorescent paints are all lightfastness III and are intended to be seen in the dark and under blacklights (although they still remain vibrant in regular lighting). This makes these paints ideal for specific types of installations that aren’t designed to last, for example, seasonal Halloween events.
