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

概要

Conservation and Restoration of Western Paper

abcwhile high acyl gels set at much highertemperatures. It is the acyl groups that havea significant influence on gel characteristics.The ability of gellan gum to gradually releasewater molecules into the paper, and in turnabsorb soluble degradation products is oneit’s most advantageous qualities. Because ofthe slow, constant introduction of moisturevia gellan gum, the effects of aqueousswelling are minimized, a consideration thatis critical when treating works with distinctdimensional qualities, like platemarks,embossings and surface texture. The idealconcentration of gellan gum will depend onthe hydrophilic nature of the paper.In order to choose the appropriate gelpercentage, the conservator must subjectivelyassess the wettability of the paper support.This is affected by the porosity of the paper,fibre type, sizings and coatings, and thestate of preservation of the paper. The moreabsorbent (hydrophilic) the paper is, thehigher the concentration of gellan gum used,as it will give off less moisture (Diagram 8).Photos 21 a-c. Gellan gumDiagram 7 Gellan gum structure5-1. GELLAN GUM PREPARATIONFor use with paper artifacts, the gellan gumis normally prepared in the range of 2-4%concentration to make a semi-rigid layer.A saline solution is prepared with calciumactetate (0.4 g/L calcium acetate), to whichthe gellan gum powder is added. The gelpowder is quickly whisked into the salinesolution to create a colloidal dispersion. It iscovered and heated in the microwave untilthe dispersion turns into a slightly yellow,transparent solution. Complete hydrationof the gel occurs at 75-100 degrees Celsius.72