The use of agar as a solvent gel in objects conservation

Cindy Lee Scott

Abstract

Agar, or agarose, is a rigid polysaccharide gel that has found use in conservation cleaning treatments of three-dimensional porous objects in recent years, most notably by Italian conservation scientists Marilena Anzani and Paulo Cremonesi. Used strictly as an aqueous gel, it has shown great promise as a poulticing material on porous plaster substrates for the removal of surface particulate matter and water-soluble soiling.

Agar is readily soluble in hot water, stable in both alkaline and acidic conditions, and (prior to adding other materials) is a safe, non-toxic, and eco-friendly material. The dispersion rate of agar can be tailored to the treatment by adjusting the concentration of the solution. In addition, agar acts as a molecular sponge; the gel, when used with solvents, is both a poulticing material as well as a solvent gel, solubilizing the impurities, drawing them away from the surface, and holding those materials within its gel matrix. Post-treatment analysis of cleaned surfaces and used gels using Fourier transform infrared spectroscopy and ultraviolet-induced visible fluorescence photography indicate that the gels show great promise with respect to clearance.

This paper builds upon the work of Anzani et al. (2010) by using agar as a support material for multiple solvents as well as other aqueous cleaning solutions. Specifically, its uses for the cleaning of and adhesive reversal on three-dimensional objects are explored.

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