Sarah Spafford-Ricci attends CAPS, a workshop on cleaning of acrylic painted surfaces

Sarah Spafford-Ricci was fortunate to be chosen as an attendee at a “Cleaning Acrylic Paintings” (CAPS) workshop organized by the Getty Conservation Institute (GCI) and held in August 2014 at the Canadian Conservation Institute (CCI) in Ottawa.  Eighteen conservators from Canada, the US and Europe attended the four day workshop, which included lectures on new advances in cleaning of acrylic paints and hands-on testing of different materials and approaches.  The GCI CAPS workshops bring new scientific discoveries in the cleaning of acrylics directly to practicing conservators, and results from the workshop are used as a basis for advancing this field of research; this was the fifth CAPS worldwide, but the first Canadian venue.  Previous sessions have been held in Los Angeles (Getty), New York (MOMA), London,UK (Tate), Washington DC (Lunder) and Australia (New South Whales).  Information on the CAPS series of workshops can be found at http://www.getty.edu/conservation/our_projects/education/caps/

Testing cleaning acrylic paint with various solutions prepared in the CCI lab.

Participants compare results.

The beautiful CCI lab is heaven for conservators!

Cleaning acrylic paintings has been a challenge for paintings conservators.  Dirt and grime becomes tenaciously adhered to acrylic surfaces due to the physical properties and composition of acrylic media.  Acrylic paintings can be very sensitive to aqueous (water-based) cleaning solutions; non-polar organic solvents are safe for the surface yet have poor cleaning efficacy.  Acrylic paint surfaces can also exhibit marked changes in gloss, clarity and character when cleaning is attempted, and may also clean unevenly.  Yet, as is well known in the FSR conservation lab, the appearance of an acrylic painting is very dependent upon the maintenance of subtle surface characteristics; thus, the need for a thoughtful and customized approach to cleaning acrylic paintings is essential!

The workshop in Ottawa was ably instructed by eminent conservation professionals: Tom Learner and Alan Phenix, scientists at the Getty Conservation Institute, Bronwyn Ormsby, Senior Conservation Scientist at the Tate, London, and Chris Stavroudis, a private conservator in Los Angeles, CA.

Alan Phenix demonstrates preparation of micro-emulsions

An affordable mini-scale is used to precisely weigh micro-emulsion components

Participants learned an enormous amount about the technology of acrylic paints and the cleaning of acrylic painted surfaces.  Sarah was able to test commercial and custom-prepared cleaning materials on acrylic paint surfaces, and discussed materials, techniques, applicability and effectiveness.   Of particular interest were new testing protocols for cleaning acrylic media, control of conductivity in aqueous cleaning systems, formulation of new micro-emulsion formulas with water/ nonpolar organic solvents/surfactants, comparative effectiveness of dry surface cleaning materials and the use of silicone solvents and silicone gel cleaning preparations.  A very important conclusion was that acrylic paint tends to separate over time in the film, and it must be cleaned with a different protocol from the cleaning of oil films.  Whereas water is generally safe for cleaning oil paintings, water can be aggressive on acrylic paint films.  Acrylic paint films respond better to high conductivity cleaning solutions with a controlled pH.

Cleaning with pure water caused swelling and opacity in the acrylic paint (blue arrow) whereas a solution of high conductivity was less aggressive, resulting in a paint film that retained its integrity (red arrow).

Various cleaning solutions awaiting use.

Back at the FSR lab, the conservators are already acquiring new cleaning materials and applying the testing and cleaning systems that were presented.  In September, the FSR paintings conservators cleaned an oversize acrylic painting by David Millar, received from the Yukon Department of Tourism, removing dirt and grime with the new cleaning materials and systems.

Back at the lab, conservators clean a large acrylic painting with high conductivity, pH controlled solutions.

Sarah Spafford-Ricci, Principal Conservator of Fine Art