The application of enzyme-containing methylcellulose gels for the removal of starch-based adhesives in albums

Starch paste, modified with aluminium sulphate, causes heavy damage to pasted papers as a result of the embrittlement and hardening of the adhesive that hardly swells at all in water. The detachment of several hundreds of prints in the Graphic Collection Albertina from albums without damaging the paper will be done by means of enzyme poultices working over a strictly limited area within the books. To maintain the activity of the enzymes under the low-humidity conditions required, the gel contains additives. Under suitable treatment conditions the enzyme residues in the paper can be lowered to a negligible level. Through artificial ageings of test samples, the safety and validity of the poultice components and the treatment conditions were investigated. The shelf life of the enzyme gel after storage over several weeks can be determined by using a staining test with starch-impregnated papers. The importance for avoiding amylase products of low purity is stressed. -- ICCROM