The October meeting of the Washington Conservation Guild dealt with pressure-sensitive tape and three techniques for its removal from paper. It was presented by Merrily A. Smith, Norvell N. N. Jones, Susan Page, and Marian Peck Dirda.
Pressure-sensitive tape was first developed in 1845 by a physician who made a surgical tape by devising a method of applying natural rubber to a cloth carrier. The next major application of pressure-sensitive tape took place in the 1920s when 3M Company applied adhesive to a paper carrier, creating masking tape that aided in the production of two-toned painted cars for the automobile industry. Gradually, as the technology of tape production developed, the adhesive component changed to synthetic rubber compounds and a new transparent backing material made from regenerated cellulose, called cellophane. In the 1950s cellulose acetate and its copolymers came into use as tape backings and synthetic polymers combined with resins came into use as adhesives. Among the first of these was Scotch Brand #810 Magic Mending Tape, which consists of a matte-finish cellulose acetate carrier and an acrylic polymer adhesive. The so-called "archival" pressure-sensitive tapes were developed in the 1970s. They have paper carriers and an acrylic adhesive mess.
One technique for removing pressure-sensitive tape is to immerse the entire object in an organic solvent. If paper and media can tolerate it, immersion is most desirable because it is usually easier, quicker, and gentler than other methods. It is best suited for single leaves of small to moderate size. Pressure-sensitive tape on items that cannot be immersed can often be removed using a poultice made up of an absorbent mass such as Fuller's earth and a liquid solvent. The poultice technique permits gentle marination of the adhesive in the solvent, and also permits manipulation of the marination time, which makes this a treatment with considerable latitude. A technique that involves removal of pressure-sensitive tape with the aid of a auction table is useful for extremely sensitive materials and media. This is because the introduction of suction allows the greatest control of solvent spread. Use of the suction technique also helps prevent abrasion of solvent-sensitive inks, and movement of paper dyes and sizing.
[This report is reprinted from the January issue of the Washington Conservation Guild Newsletter, with permission. Another presentation is planned for the AIC Book and Paper Group meeting in May.]