Odkwaszanie papierów zabytkowych

The exceptional harmfulness of acid substances is the reason why deacidification should be perceived as the most important operation performed in the course of the conservation of historical objects with a paper base. The presented article is a review of the current state of knowledge on the subject.Theauthor discussesthe reasons for the deacidification of library and archival material and the assessment of the degree of their acidity by pH measurements using harmless methods.The reader is offered a presentation of the concept of the alkali reserve and its significance for the improvement of the durability of paper. A pH oscillating from 8 to 8,5, obtained in the course of the deacidification of old papers, is regarded as a minimum level to be sought during this operation.Empha sis is placed on the significance of rinsing in water and the importance of the carbonates of alkaline earths obtained in the paper as a result o deacidification.The author considers the most essential deacidification substances: calcium hydroxide, magnesium bicarbonate and barium hydroxide.A ttention is drawn to problems accompanying the treatment of manuscripts, water colours and pastels.Arti cle was written upon the basis of lectures and courses conducted by the author for students specialising in the conservation and restoration of old prints and graphic works in the Department of the Restoration and Conservation of Works of Art at the Academy of Fine Arts in Warsaw.