Rigid Solvent-Gels in Paper Conservation: A New Approach to Sticky Problems

Pressure-sensitive adhesives (PSA) present in pressure-sensitive tape or self-adhesive labels applied on paper pose substantial problems for the long-term conservation of the substrate because they degrade upon ageing, leaving embedded stains. This paper presents the development of a method to prepare agar-based solvent-gels with high organic solvent, and low water content. The objective is to provide conservators with a versatile, cheap, and easy solution to make solvent-gels for PSA removal, to be implemented as sole treatment or included in a multi-step treatment protocol. The treatment method proposed in the case-study aims at removing aged, rubber-based adhesive residues from the printed paper cover of a book. It includes the use of silicone-based solvent cyclomethicone D5 as a treatment-aid applied just before the application of the solvent-gel. The efficiency of D5 to prevent the formation of stains and tide-lines during local gel treatment is demonstrated, and potential side-effects are also pointed out.