One of the most common questions we get about our fluorescent paints is about lightfastness. Lightfastness refers to a pigment's ability to resist fading when exposed to ultraviolet light. Artists' paints are typically rated by ASTM (American Society for Testing and Materials) standards for each particular pigment in the paint. For more common pigments one can find the lightfastness rating listed as:
I: Excellent; II: Very Good; III: Fair; IV: Poor; V: Very Poor
All pigments will fade over time due to the effects light, heat, and humidity. In order to be considered "archival" pigments need to be rated either ASTM I or II. Fluorescent pigments do not have a standardized lightfastness rating because each manufacturer has patented and secret processes that they use to produce their pigments. We selected our pigment supplier based on the quality of their pigments.
We can, however, get an idea of the lightfastness of our neon colors by conducting blue wool testing. To do this, we painted our six original neon colors on a white piece of paper and exposed only half to direct sunlight. We also exposed half of a blue wool card directly underneath the painted colors. We did the same process for our seven neon fluorescent watercolor paints. Over time have been tracking the fading of the blue wool and checking to see if there is any observable fading of the paints.
As you can see below, the blue wool test strip shows visible fading on all 8 of the blue strips. The neons exposed to the same amount of daylight show no fading or color-shifting. Blue wool strips with fading on the top two blue samples are equivalent to an ASTM I - Excellent Lightfastness. Since the neon oil paints do not show fading at this point in exposure, they would be listed as ASTM I. However, due to the fugitive nature of the fluorescent qualities, we cannot label them with this rating.
Closeup of Gapka Fluorescent Neon Oil Paints
In the summer of 2023, we introduced a new line of watercolor paints. Testing of the neon fluorescent watercolors revealed that they are not as lightfast as our oil paints. Although we use the same high-quality pigments, it is not unexpected for paints manufactured with different vehicles to have different lightfastness ratings even when the same pigment is used. The fading below occurred before the blue wool test strip reached ASTM III levels. Our neon fluorescent watercolors fall in the ASTM III - Fair Lightfastness to ASTM IV - Poor Lightfastness range. We are in the process of experimenting with additives that would improve the lightfastness of the watercolors. It is always best to protect your artwork from direct sunlight exposure.
If you are interested in the chemistry and history of UV fluorescent paints, you can read more at: https://journals.openedition.org/ceroart/1659.
* These tests are reported for informational purposes only and do not represent a guarantee of lightfastness.
[Updated September 2023]