Revising Artist Color Lightfast Standards

Current testing conducted by our Lab, led by Junior Formulator Trevor Ambrose, with the support of our Senior Formulator, Ulysses Jackson, has revealed the need to update the over 40-year-old ASTM Standards for Lightfastness of Artist Materials. While a good deal of anecdotal evidence has suggested that these standards have needed revision, to date no good data set has been developed, which would allow other researchers and manufacturers to coordinate and conduct their own investigations. We have continued to work with our colleagues at the ASTM committee D01.57 to create a round robin testing of our concerns, including a long-time commitment from Natural Pigments, George O’Hanlon and a new partner, Pierre Sanchez from Colart. We welcome the participation of other colleagues, especially as some of the new protocols that we’ve investigated lower the costs dramatically for companies to test their own colors.

We certainly owe an incredible debt of gratitude to the late Henry Levison of Permanent Pigments and Liquitex fame who produced in 1982, the complete set of reproducible lightfastness results in both oil paints and acrylic artist colors. These eventually became the tests that were introduced in the standards in 1992. By using both Ultraviolet bulbs, Xenon cabinet and outdoor testing panels, Henry, along with other material scientists, including Ruth Johnson Feller, and artist, Joy Turner Luke and Mark Gottsegen, sdevised the standardized testing protocol. The tests included evaluation of fading or changes in the masstone (or undiluted color) and colors tinted with white (to a reflectance of 40% or about 1 part color to 10 parts white). I had the good fortune to meet Henry in 1981, while participating on the ASTM Committee for Artist Materials. Henry, after leaving Binny and Smith, started his own independent Color Lab and generously donated all his test panels to the work of the ASTM Committee.

To date, every artist material manufacturer has used those pigment lightfastness lists that were generated to describe the permanency and archival properties of their colors. However, few manufacturers have actually used the protocols to do their own lightfastness tests. Most have simply relied on the veracity of those original results, which in many cases remain quite accurate. Henry also advocated for manufacturers to include the specific color chemical and index name on their products to assure transparency of materials for artists. These were times of significant change in the industry. Art material manufacturers were being held to higher standards.

Now 40 years later, through our own research, we have proven that those standards and the protocols need an overhaul. In addition, we have found that, especially with new organic pigments as well as some inorganic pigments, that manufacturers can no longer rely on a static list. They must do their own lightfastness tests with their own formulations and pigment supplies to assure they are accurately assessing the permanency and archival properties of their own materials. The current research article, included in JustPaint.org by Trevor, evaluates a wide range of colors within our Williamsburg Oil Colors line to show the variability of pigments using different whites as well as the relationship of lightfastness to concentration of pigment, which heretofore has not been recognized as a condition for lightfastness. We have conducted similar studies with our other mediums including our Golden Artist Acrylics and QoR Artist Watercolor. We will continue to publish those results with the hope that the ASTM standards that we and many artists have relied upon, can again be used with confidence by artists and art manufacturers.

I am incredibly proud of the work and diligence of our research team to have conducted this long-term evaluation and study. Please click on this link ASTM Lightfastness Testing for Oil Paints grab a large cup of coffee and get comfortable to read the complete research paper.