REMOVAL OF PRESSURE-SENSITIVE LABELS FOR LIBRARY APPLICATION A Study of the Use of Agar as a Solvent Gel

Sammanfattning: The purpose of this study was to investigate pressure-sensitive labels for library application, techniques, and considerations for their removal from paper substrates. The aim was to use information from the literature to design a method for the removal of pressure-sensitive labels from paper covered half bindings using agar, commonly known as agar-agar, as a solvent gel. The study is divided into two parts: a literature study with the aim to compile information relevant to the purpose of the study, and a case study for the removal of barcodes from three books made available by the Humanities Library of Gothenburg University Library. To analyse the barcodes, stereo microscopy, Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) spectroscopy, and spot tests were conducted. Agar was subsequently tested and evaluated as a solvent gel in a practical removal. Analysis of the barcodes on the studied books showed that they are built-up of three layers with a pressure-sensitive adhesive closest matching that of a poly(methyl acrylate) emulsion. A 2% agar gel was divided into three batches and mixed with 20% ethanol, 20% 1:1 acetone:ethanol, and 29% ethyl acetate. While all of the removals were considered somewhat effective, the ethyl acetate agar gel gave the best results with the least damage to the surface layer of the paper. Based on the evaluation it could be concluded that agar shows great promise as a solvent gel. The study showed that issues to take into consideration can be roughly divided into three aspects: 1) the purpose of the label, and historic circumstances related to the label; 2) whether the label obscures or contains information crucial to the interpretation of the object as an entity; and 3) damages caused, or potential damages that might arise from its continued adherance to the substrate.