CONSERVATION OF ACID-PAPER - STUDIES CARRIED OUT IN THE CHEMISTRY-LABORATORY OF THE ISTITUTO-CENTRALE-PER-LA-PATOLOGIA-DEL-LIBRO

The paper reviews the main research work on deacidification carried ou t in the Chemistry Laboratory of the I.C.P.L. since the end of the 60s . Studies were made, in particular, on the effects of calcium and magn esium bicarbonates, of barium and calcium hydroxides and of magnesium methoxide. It is emphasized that treatment with deacidifying solutions , especially with calcium and magnesium bicarbonates, slows down the d egradation of initially acid paper. The difference in behaviour of alk aline solutions of magnesium salts on non acid pure cellulose paper ac cording to the type of artificial ageing is also noted: the influence on stability was negative during ''dry'' ageing (about 1-2% R.H.) and positive in ''wet'' ageing (R.H. > 40%). The effect is not noticeable on previously ''deionized'' pure cellulose paper. The subsequent studi es showed that treatments with high concentrations of alkaline sodium salts are definitely damaging for conservation, while very low concent rations (1 mmole for 100g of paper) are ''beneficial''. It is thus hyp othesized, in relation to accelerated artificial ageing, that the diff erent behaviour of alkaline salts of the 1st group (e.g. sodium), comp ared to those of the 2nd group (e.g. calcium or magnesium), is linked to their different solubility.