CONSERVATION OF BROKEN DRY PLATE NEGATIVES FROM FRANCIS AMIN’S PRIVATE COLLECTION – A SCIENTIFIC ASSESSMENT OF SELECTED ADHESIVES

Abstract

Institutions housing photographs and documents (e.g. archives) usually include large collections of glass plate negatives of significant historical value among their collection. Gelatin dry plates were the most common negative process in the years between 1880s and the 1920s. Gelatin dry plate negatives consist of a layered structure. This structure can be divided into three components: the primary support, glass; the binder layer, gelatin; and the final image material, metallic silver grains. As a result, dry plate negatives have a complex physical and chemical nature that must be taken into consideration if they are to be preserved into the future. One common preservation issue presenting a true challenge to photograph conservators is the treatment of broken glass negatives, mainly caused by improper handling and misuse, but also as a result of disasters (e.g. earthquakes). There are two different approaches for assembling broken glass negative: i) by preparation of a non-adhesive housing mat, and ii) by using an adhesive such as Paraloid B72 and epoxies. This study aims at assessing three different types of adhesives for use in the assembly of broken fragments of dry plate negatives. Tested adhesives were exposed to humid heat artificial ageing at a temperature of 80°C and 65% RH for 5 day. Evaluation was carried out using several techniques including visual inspection, colorimetric measurements, bursting test and Fourier transform infrared spectroscopy (FT-IR). The adhesive with the best results was used for further testing to evaluate its longterm efficiency when used to repair dry glass negatives by means of visual inspection, microscopic inspection, colorimetric measurements, FTIR and burst strength test. The second part of the study includes the treatment of six dry glass plate negatives, from Dr. Francis Amin’s private collection, a famous Egyptian photo collector. The negatives mainly suffered from surface dirt, silver mirroring and breakage.