AIC's 47th Annual Meeting

Unprotected, matte painted surfaces are extremely difficult to preserve. Matte, underbound and water-sensitive paint often lacks cohesion and delaminates, is fragile and can be altered by even the slightest contact. When a consolidation treatment is required, very limited methods and materials are available that can provide both an efficient consolidation and that do not alter the optical characteristics of the paint. Among these, Funori, Jun-Funori, Isinglass, and diverse cellulose ethers, such as Methocel A4C have relatively established use. These materials are frequently applied through ultrasonic misting because the powdery surfaces cannot tolerate mechanical action during brush-application of liquid-phase consolidants. However, nebulizing conventional materials can be problematic because of their high viscosity, which allows only for very low concentrations of the biopolymers to be nebulized, often insufficient to stabilize the paint. As a result, multiple applications may be required that expose the paint to excessive amounts of water, which increases the treatment risks, and is time consuming. A new solution to this problem is being developed by exploring a previously unreported group of ultra-low viscosity (ULV) cellulose ethers. In contrast to conventional consolidants, these materials are characterized by their extremely low viscosity (as low as 2.4 mPas at 2 wt%), far lower than Methocel A4C (400 mPas), Funori (180-250 mPas) and Isinglass at the same concentration. Tests demonstrate that the new ultra-low viscosity consolidants can be nebulized at considerably higher concentrations, and are sufficient to stabilize matte powdery paint in a single or very limited number of applications. Consolidation is a non-reversible procedure, so it is critical to explore the long-term stability of any materials used for such a treatment. The methodology for our feasibility study includes assessment of viscosity, nebulization potential, cohesive properties, as well as artificial aging and assessment of optical changes of surfaces treated with the new consolidation media. The experimental and artificial aging results will be assessed against Methocel A4C, Jun-Funori, Isinglass and synthetic media used in the treatment of matte surfaces. Furthermore, UV tagging will be used to trace the penetration and distribution of the consolidation media into the substrates. The ULV consolidants will also be tested on mockups as well as case study treatments on 20th c. paintings and works on paper. Initial artificial aging results suggest that the ULV cellulose ethers are highly stable, while first practical applications reveal minimal impact on the optical characteristics of the matte painted surface. The outcomes of the proposed paper have the potential to supply conservators with a highly effective, safe, and stable consolidation medium that would allow for the optimization of ultrasonic nebulization methods used for the consolidation of matte, powdery paint in traditional, modern, and contemporary artworks and other cultural heritage objects.