PERMANENCE OF PAPER IN POLISH BOOKS OF THE PERIOD 1900-1994

The study is devoted to the estimation of the permanence of paper in 1 395 Polish books of the period 1900-1994. As features for the evaluati on of the permanence of paper, the folding endurance and the pH measur ements by a cold extraction method have been chosen. Categorization of the durability of the paper was undertaken according to the classific ation of William James Barrow 1901-1967. For multivariate analysis of the measured features over the period 1900-1994, divided into decades, the method of cluster analysis was chosen, applying the single linkag e method, according to the Lance-Williams formula. For the period 1900 -1979 in consecutive decades, from 93 to 100% of volumes were made of paper the permanence of which is categorized as first or second class, according to W. J. Barrow's classification.