ブックタイトルConservation and Restoration of Western Paper

概要

Conservation and Restoration of Western Paper

tert-butylamine complex was added. Thelithograph was sandwiched betweenthe cast gel sheets for two periods of 60minutes, with impressive results. Thereductive bleaching gel has a milky white,opaque appearance, compared to the moretransparent stock gellan gum gel (Photos31a, b).5-6. DEACIDIFICATION WITH GELLANGUMPreparation of gellan gum for deacidificationis similar to the procedure for reductivebleaching. Calcium propionate (3.5-5g/L isadded to a calcium acetate saline solution(0.4g/L), before whisking in the gellan gumand heating it in the microwave.Gellan gum applications and solutionpreparations are summarized in the tablebelow (Diagram 9).Gellan gum has proven to be a valuableaddition to the arsenal of materials used inthe conservation labs at LAC. The followingadvantages have been noted:? Gellan gum is safe; easy preparation anddisposal (note exception for Borane gel);? Provides an even, highly controlleddelivery of moisture;? Retains dimensional qualities, texturesand topographical qualities of the objectbeing treated;? Has variable flexibility, so is effective incleaning uneven or multi dimensionalsurfaces;? Is transparent to permit observation ofobject during treatment;? Does not leave a residue;? Can be used for local application oroverall treatments, and? Can be used to deliver a variety ofchemical treatments.The preceding examples illustrate theversatility of gellan gum, and the authorhopes that the conservation community willuse these treatments as a stepping stone andAPPLICATION GELLAN GUM FORMATION COMMENTSOVERALL CLEANINGLOCAL STAIN REMOVALBLEACHINGDEACIDIFICATIONDiagram 9 Gellan Gum Applications and SolutionsLess rigid gel:2-4g/L gellan gum powder in H2O*More rigid gel:2-4g/L gellan gum powder in saline solution(0.4g/L calcium acetate)2-4g/L gellan gum powder in saline solution(0.4g/L calcium acetate)*Quality of water affects rigidity: thelower (or absence of cations), theless rigid the gelCast gel layer is milky and moreopaque in appearancePPE must be used when preparingAFTER heating gellan gum in microwave,borane solution Requires properquickly whisk in 7g/L borane tert-butylaminedisposal as hazardous waste (refercomplexto MSDS)2-4g/L gellan gum powder in saline solution(0.4g/L calcium acetate)Add 3.5-5g/L calcium propionate* to salinesolution BEFORE heating in microwave*Quantity of calcium propionatedependent on desired alkalinereserveCast gel layer is milky and moreopaque in appearance78