Why deacidify if it is (hardly) visible?

Frequently asked questions / Why deacidify if it is (hardly) visible?

Deacidification of paper is a chemical intervention that aims to increase its pH (or reduce the acidity, which is the same).
Usually this treatment has no visible consequences in the short term, and the document remains -aesthetically- almost the same as it was. However its consequences are of crucial importance because they affect the main causes of fibre paper degradation.

The contribution of an alkaline buffer or the neutralization of the current acidity in a document significantly slows its ageing. Ageing might be harmful when documents are really old, but also when the paper has not the best of qualities. Acidic media increases the prejudices of ageing (oxidation cellulose and its consequent weakening and yellowing).
The longer are the cellulose chains, the more strong they are and offer major mechanical resistance. Therefore a good chemical stability and an optimal pH guarantee their durability. Recommended pH values are among 7 and 8,5 (alcaline values).

Yest deacidification does not necessarily  clear darkened papers (or not significantly, in most ocasions), it is true that an acidic paper has usually suffered a darkening or yellowing process. Therefore if we stop o retard this process, we hinder the paper from an increasing yellowing along its ageing.

Deacidification will be normaly done by non-aquesous spraying when it is not necessary or possible to wash the paper, and on a water bath on the opposite case, usually with calcium hydroxide (lime).Compartir IGUAL citant AUTORA i ENLLAÇ


watercolour restoration  posters deacidification foxing on the edges and first pages