<- Back To Mural Best Practices Page
Read about mural paints and coating testing and initial results - >
Winterthur/University of Delaware Program in Art Conservation's Mural Materials Research
The Winterthur/University of Delaware graduate programs in art conservation have launched a multi-year project to test paints and coatings currently used by outdoor muralists in Philadelphia (whose Mural Art Program has resulted in the painting of more than 2,700 outdoor murals) and other U.S. cities. A team of graduate students and faculty has surveyed key murals eight to twenty-years old and gathered observations regarding fading, chalking, and flaking of the paint surfaces. This work has now resulted in the restoration of one of Philadelphia's best-loved murals, Common Threads by Meg Saligman. Click here to read about it.
 University of Delaware group in front of Common Threads, Meg Saligman, 1997, |
The first phase of the University of Delaware project in 2005 was based on paints and coatings suggested by artists and conservators on the Rescue Public Murals team of Advisers. Student Jessica Keister, working with Dr. Joyce Hill Stoner, Dr. Joseph Weber, and Richard Wolbers, prepared 922 (3" x 3") sample squares to test Golden, Novacolor, and Sher-cryl acrylic paints, and Keim potassium silicate paints. Red, yellow, and blue paints taken directly from the containers or mixed with white were applied to prepared supports in order to study their photostability and the photo-catalytic effect of titanium dioxide (in the white paint) on fading.
 Jessica Keister with samples of mural paints on the grounds of Winterthur Museum and Gardens |
The following coatings are also being tested: Paraloid B-72 and Novacolor varnish (both with and without CIBA 777), Golden MSA varnish with UVLS, and Triangle catalyzed polyurethane "anti-graffiti" coating. Additional coatings will be studied by graduate student Amanda Norbutus in 2008-2009. Samples are on south-facing racks at a 45-degree angle; spectra and color change of each sample are being measured periodically by microspectrophotometry and colorimetry.
 Richard Wolbers and Jessica Keister mixing a test coating for mural samples |
In the second phase of the project, in 2006 and 2007, graduate student Amber Kerr-Allison, working with Richard Wolbers, tested an ultraviolet-light absorbing coating that could provide protection from light exposure and weathering while providing a surface barrier to shield the paint from dirt, grime, and graffiti. Other design goals for this UV protective coating were that it be aqueous (water) based for safe application over large areas, that it could be evenly applied and would remain clear without discoloring, and that it would be reversible using an aqueous-based system relying on a targeted pH level rather than organic solvents for safe, effective removal. The reversibility of the coating at a higher or alkaline level of pH means that the coating is unaffected by acid rain and that it is within a safe working zone for the paint film beneath. The UV absorber used is manufactured by CIBA Specialty Chemicals. It is a Triazine, one of the more durable UV absorbers for use in protecting pigments.
 Dr. Joseph Weber with Jessica Keister and |
 Meg Saligman and Dr. Joseph Weber discussing mural materials |
In addition to testing mural materials, the University of Delaware group hopes to increase awareness among mural project administrators regarding the importance of planning for future maintenance in addition to involving conservators, the original artists, and members of the community in the original design and protocol for each mural. For example, a project may be more amenable to using a higher-cost paint or coating if they have evidence that it will save money in the long term.
For additional information, contact Joyce Hill Stoner at the Winterthur/University of Delaware Program in Art Conservation at jhstoner@udel.edu.
Photos by Joyce Hill Stoner