Water-resistant adhesives for paper, 1870–1920.

Removal of tenacious adhesives is one of the major challenges in paper conservation. This article examines what water-resistant adhesives were used from 1870 to 1920 and comments on the implications of these findings to the practising paper conservator. Water-resistant formulations were found to be more likely to contain animal glue and linseed oil as binders. Other non-water-soluble binders, such as plant resins, shellac, gutta-percha and casein, were also used, as were mixtures of starch or flour paste with animal glue. A variety of chemical hardeners were employed, including tannic acid, formaldehyde and alum. The addition of substances containing multivalent metals such as copper, lead, calcium and aluminium may also have had a hardening effect, though they may not have been added for this reason. [ABSTRACT FROM AUTHOR]