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

概要

Conservation and Restoration of Western Paper

taste, obtained from different plant sources.One of its main features is their ability toform black, dark brown and green complexeswith iron salts. 3The main source of tannins for iron gallinks were galls, which are growths that occurin some trees (mainly oaks) as a protectiveresult of the action of insects known as gallwasps. 1 Although the galls were the principalsource of tannins, some other vegetal sourceswere used, as the chestnut wood, sumachleaves, and bark of oak, poplar, willow andfir. Sometimes 'recycled' tannins were used,soaking pieces of leather (which had beentanned with tannins) in water. 1The tannin obtained from the galls isgallotannic acid, consisting of a glucosemolecule with five molecules of gallic ordigallic acid. 3 It is the gallic acid that reactswith iron salts to form a black complex, soit was necessary to hydrolyze (separate)gallotannic acid molecules to obtain thelargest amount of gallic acid molecules.3. Gum arabic: It is a polysaccharideexudate of the Acacia Senegal tree or otherkinds of African Acacia; it is soluble in waterand has a yellowish-white color, with amberlike appearance. 8Gum arabic was the main binder used inthe manufacture of iron gall ink, modifyingits viscosity and flow, producing a greaterbrilliance and deeper color, and binding theink and the paper surface. 4 The gum alsocreated a protective layer that protectedit from excess absorption of atmosphericoxygen. 34. Additives: Almost every recipe for irongall ink mentioned one or more additives tomodify the characteristics of the ink. Someof the most common ones are:? Acids: Used to accelerate the hydrolysisof the gallotannic acid and also toslow down the oxidation of the ink.Hydrochloric an acetic acid (vinegar)are commonly mentioned. 3? Dyes: Usually they served as provisionalcolorants, to facilitate writing when theink was freshly prepared and the colorwas less intense. It was very common touse indigo for this purpose. 1? Fungicides: Added to prevent or slowmold growth in the ink, most commonlyused fungicides were acids, alcohol,cloves and alum (aluminum salt).? Alcohol: In regions with low temperatures,the addition of alcohol (like brandy)to the ink would protect it againstfreezing. 4The permanence of the inkThe large amount of documental heritagewith iron gall inks in Western cultures is nocoincidence, and can be understood from themanufacture process of the ink. Its successand widespread use relies on the solubilityof the ferrous gallate formed when the ironsulphate reacts with the gallic acid, and tothe insolubility of the ferric gallate, after theoxidation of the ink starts.In more simple words, when the ink isfreshly prepared it is still soluble and hasa higher penetration rate in the writingsupport, but as it naturally oxidizesit becomes insoluble, therefore highlypermanent. Unlike carbon ink, iron gall inkcould not be scraped or easily washed.If the ink is used in the soluble or ferrousphase (freshly prepared), it behaves as a47