41st Annual Meeting – Book and Paper Session, June 1, “Testing the Waters: Applying New Techniques to the Cleaning of Acrylic Paint Film by Amy Hughes and Daria Keynan”

New York-based paper conservator Daria Keynan and Amy Hughes, third-year graduate student at NYU Institute of Fine Arts, shared exciting new contemporary cleaning techniques that have the potential for more effective and efficient treatment of paper-based objects by custom-matching the pH and conductivity modular stock solutions to the original object. This presentation was a wonderful and inspiring cross-specialty exploration of how paintings conservation techniques can be applied to paper conservation – and who doesn’t want more tricks up their sleeve?
Keynan was first introduced to the concept at the 2011 CAPS (Cleaning of Acrylic Painted Surfaces) workshop at the Museum of Modern Art. (I am now kicking myself for thinking that these workshops wouldn’t necessarily apply to my work as a book and paper conservator, so jealous!) To date there have been four innovative series of CAPS workshops supported by the Getty Conservation Institute to further the dialogue between theory and practice among conservation scientists and conservators as well as to introduce the concept of modular cleaning systems. Struck by her experience at the 2011 CAPS workshop and impressed by their use for treating acrylic paint films on art on paper, Keynan has further explored the use of pH and conductivity customization for other areas of paper conservation.
The CAPS workshop introduced several different cleaning techniques to minimize removal of surfactants when cleaning acrylic film surfaces. Acrylic paint and modern materials are scary (my word, not theirs.) Emulsions are often complex with many proprietary and artist-introduced ingredients. Colors react differently after drying, in treatment, and as they age. Some colors may be more sensitive to chemical and mechanical cleaning than others. Surfactants and other soft solids may never solidify, creating a tacky surface that can attract dust and grime. Conservation treatment, particularly aqueous treatment or mechanical cleaning with damp cotton swabs, can introduce immediate disfiguration like abrasion or swelling. Readily soluble surfactants can leach to the paint film surface or verso of the paper substrate. Treatment can also jumpstart deterioration that is not apparent until the future due to unknown chemical and mechanical consequences.
Of the many cleaning techniques available within contemporary conservation, Hughes and Keynan limited their presentation to the customization of pH and conductivity as a more finely-tuned and safer aqueous cleaning technique. They shared their methods by highlighting the treatment of works of art on paper brought to the Daria Keynan Paper Conservation in Manhattan for treatment where adjusted water – tweaking the pH and conductivity of the deionized water – was a key factor of success.

HughesKeynan_slide14_2013BPGIn the Garden
(1986) by Paula Rego was surface cleaned to reduce dust and embedded grime altering the surface sheen. After dry cleaning with cosmetic sponges, Hughes tested various acrylic paint colors for pH and conductivity testing. Cylindrical pellets of cast agarose gel (recipe and supply information to be published in their BPG Annual post-print) were uniformly shaped with a medical-grade biopsy punch. (Heed Hughes’ warning, online image searches for “biopsy punch” are not for the weak-stomached!) The agarose pellet, acting like a poultice, was placed in contact with the acrylic paint film for 45 seconds to absorb the surface pH and conductivity. Agarose was selected because it imbibes the surface readings without visibly swelling the paint with excess moisture as in more aggressive techniques like local, direct application of deionized water. Keynan explained that the contact time of the agarose pellet can be matched to the estimated treatment time so that testing parameters can meet real-world treatment situations, increasing the predictability and reproducibility of testing results.
HughesKeynan_slide15_2013BPGThe pellet was transferred from the paper surface to the well of a pocket-sized, hand-held pH meter (Horiba Laqua pH Tester from Cole-Parmer) to record the pH of the paint surface. A droplet of deionized water was then placed on the pellet and transferred to another pocket-sized, hand-held conductivity meter (Horiba B-171 Twin Conductivity/Salinity Pocket Tester from Cole-Parmer) to record the conductivity of the paint surface. (As someone who absolutely dreads calibrating our cumbersome pH meter I was overjoyed to hear how easy these were to use – my purchase order request is already submitted.)
The conservators used the recorded pH and conductivity for a given area of the painted surface to identify the optimal working solution for cleaning. They selected from among a variety of premixed stock solutions that were created according to the CAPS workshop directions using deionized water, glacial acetic acid, and ammonium hydroxide in a range of ph 5-8 and conductivity 1000-6000 µS (micro Siemens.) Once mixed, the stock solutions can be stored in the refrigerator for up to several months. Keynan also reported that they often add several drops of an antimicrobial preservative for a longer shelf life.
The embedded material and dust on In the Garden released easily with 3-4 passes of lightly damp, pre-blotted cotton swab rolled over the surface. Hughes warned that since acrylic film is susceptible to abrasion it is important to monitor the paint surface during treatment. Cotton might not be appropriate for all acrylic surfaces so additional experiments with different swab materials may be useful. Similar success was seen in the mold removal and stain reduction of Maquette for Smoking Cigarette Relief (1983) by Tom Wesselmann.
Since Superstorm Sandy hit New York City in October 2012, Keynan’s studio has seen many complex treatments because of the unusual and unknown composition of the storm water which was often contaminated by sewage (uh, gross.) Many of the paper-based objects were stained with tidelines that were difficult to remove and fluoresced brightly under UV. Standard paper conservation techniques often visibly removed the tidelines but were deemed unsuccessful since under UV they shifted along the paper fibers or sank but were not completely removed from the paper support. She related that altering the pH and conductivity of her treatment water dramatically improved treatment results. Removal of the fluorescing blue tidelines (both external and internal) was achieved by local application of the adjusted water and using fumed silica poultices to block the formation of new tidelines.
HughesKeynan_slide34_2013BPGThe last example Keynan shared was a sample of naturally aged 2-ply paper board. (This was exciting, anyone else ever stare blankly at a nasty tideline on an illustration board and just sigh?) Traditional and adjusted treatment waters were applied with cotton swabs in several passes to clean the surface with varying results. Traditional deionized water cleaned less and was uneven, leaving a soft and vulnerable surface. The solution set at pH 6.6 and 6,000 µS glided more easily and had more even results. It also felt more controllable when working. The third sample solution set to pH 5.5 and 14,000 µS gave the most effective cleaning but in real life would probably not need three passes. After drying, the surface readings for all three areas had almost identical conductivity and pH readings.
Keynan concluded that by matching a pH- and conductivity-adjusted solution to the surface of the object it is possible to create a near chemical equilibrium at the surface to eliminate leaching from or depositing into the paint film. In treatment, using adjusted solution equals maximized cleaning efficiency with less wetting out of substrates, less pigment transfer, less repeated action, less loss of surface texture, and reduced distortion of the working area. Conservators have always adjusted pH for various uses, but by measuring the conductivity we can tailor our treatments to the physical needs of the object material with more refinement and subject it to less invasive treatment. Adjusted waters are an incredibly useful tool for improving and refining treatments in our conservation practice.
Hughes and Keynan’s presentation was an approachable and exciting take on the contemporary research going on in the field of conservation science and paintings conservation, especially as led by Chris Stavroudis (freelance paintings conservator in Los Angeles) and Richard Wolbers (Winterthur/University of Delaware Program in Art Conservation) in, well, all things related to cleaning painted surfaces and the Modular Cleaning Program.
Other presentations at the AIC meeting in Indianapolis such as “Mass Spectrometric Imaging of Acrylic Emulsion Paint Films: Engineering a Microemulsion-Based Cleaning Approach” (Paintings + Research and Technical Studies Thursday, May 30) show that the MCP and CAPS research continues. During the question-and-answer period Dr. Anthony Lagalante (Villanova University) shared that he and Stavroudis had recently recorded a video about using and calibrating the meters – it was on the cutting room floor, but will be posted to the CAPS website soon. Lagalante also sent me a link to their illuminating Studies in Conservation article that is currently available as a pre-print:

C.E. Dillon, A.F. Lagalante and R.C. Wolbers “ Aqueous cleaning of acrylic emulsion paint films. The effect of solution pH, conductivity and ionic strength on film swelling and surfactant removal” Studies in Conservation 57(1), (2014). http://www.ingentaconnect.com/content/maney/sic/pre-prints/2047058412Y.0000000076

The concept presented by Hughes and Keynan in “Testing the Waters” has the potential for wide application for all book and paper conservators. Working with stock solutions is a fast and economical lab practice. Customizing treatment solutions increases the workability and effectiveness of the treatment. Many of us in the room instantly coveted the easy-to-use digital meters as we thought of the hassle of calibrating traditional models. I’m intrigued by how this research can be applied to aqueous treatments meant to introduce alkaline reserves to acidic paper.
This was a welcome multi-disciplinary presentation that encouraged conservators from other specialty groups like PSG and RATS to attend the BPG program. I am not alone in hoping for more presentations like it at future meetings so we can all benefit from the exciting things happening in all areas of our conservation community.