Preservation Week 2014: Tape Troubles and Treatments
Today’s post was written by Claire Kenny, Assistant Research Scholar in the Barbara Goldsmith Book and Paper Conservation Laboratory.
As a paper conservator I spend a lot of time removing tape. The use of tape is ubiquitous; it is a fast, easy way to mend losses and tears in paper objects. However, it doesn’t age well and can cause damage to the object it was intended to fix, and can be time consuming and sometimes impossible to remove. Unfortunately, many collections of paper and books have been previously repaired with tape and suffer from structural, chemical and aesthetic damage as a result, but we conservators are equipped with chemicals, tools and equipment to aid in the removal of tape in order to stabilize and preserve a variety of paper-based objects. My latest treatments at the Barbara Goldsmith Book and Paper Conservation Laboratory have involved the removal of two types of tape we commonly encounter in the lab: gummed tape and pressure-sensitive tape.
What is tape?
In essence tape is a backing material coated with an adhesive. Gummed tape typically features a paper backing with a protein or starch adhesive which is activated with water. As its name belies pressure-sensitive tape requires light pressure to form a bond between the adhesive and desired surface, without the use of heat or chemicals. Pressure-sensitive tape comes in many forms; the most common include Scotch® tape, also called Magic™ tape, sticky-tape, sellotape, or self-stick tape, and masking tape.
Why tape is bad for paper
Tape is composed of layers as shown in this diagram:
The deterioration process of pressure-sensitive tape changes the chemical structure of the tape and the adhesive mass migrates into the paper support, causing staining, embrittlement and spreading of the adhesive beyond the desired area. As the tape ages further it becomes brittle and less sticky, and the carrier may eventually fall off leaving a dark stain that can be impossible to remove despite our best efforts.
Book of the Calendar
The Fales Library holds the Kaplan Collection of Judaica and Hebraica, which includes this beautiful edition of Book of the Calendar, printed in Offenbach in 1722, written by astronomer and mathematician Eliezer ben Jacob Belin. The book is a guide to harmonizing the astronomical and Jewish calendars, and features beautiful woodblock print illustrations, charts, and hand colored multilayered paper volvelles, charts with movable parts considered to be early analog computers.
When the book arrived in the lab there were three manuscript pages attached at the front of the book to the flyleaf and bookplate with several layers of transparent pressure-sensitive tape. The tape was significantly deteriorated, and the thick layers of tape rendered the manuscript pages difficult to turn, making their contents inaccessible to curators and scholars. In consultation with the Librarian for Printed Books, Charlotte Priddle, it was determined that these manuscript pages likely represent calculations based upon the contents of the book.
In order to improve the function of the object as a whole and to protect the pages from further degradation, the tape had to be removed. The tape was mechanically removed with a thin metal spatula and a Zephytronics Air Pencil. The air pencil blows a steady, gentle stream of warmed air onto the tape, softening the adhesive enough to allow the spatula to slide between the tape and the manuscript page below. The tape carrier was then lifted carefully away and the sticky adhesive residue was reduced with a crepe eraser. Once the tape was successfully removed the pages were cleaned and mended and can now be safely studied.
Un Marino: Un Heroe
This poster from the Spanish Civil War, held in the Tamiment Library and Wagner Labor Archives Poster and Broadside Collection, designed by the artist Arturo Ballester and printed in support of the Republican cause, depicts a sailor in a heroic pose. This large (63 x 42 inches) poster arrived to the lab in a polyester enclosure and featured extensive tape repairs on the back.
The poster is split vertically through the center and has many complex tears, losses and detached fragments which had previously been repaired with multiple layers of brown, gummed tape. The old tape repairs were misaligned and had failed in several places leaving behind dried tape residues. The polyester enclosure was ill-fitting and causing damage to the poster; the edges of the enclosure were sealed with double-sided pressure-sensitive tape that was partially stuck in spots to the sides of the poster. The enclosure and tape had to be removed to stabilize the poster.
Once the polyester enclosure was removed, bits of pressure-sensitive tape were mechanically removed from the edges of the poster with a thin spatula heated on a small iron. The following image shows the edge of the poster after the tape was removed.
The gummed tape was slowly removed in small sections by first softening it with a methylcellulose poultice and then gently scraping it off with a thin spatula. The tape removal took a long time – about 20 hours in total. The image below shows tape removal in progress.
When all of the tape was removed the pieces of the poster were washed in a bath of deionized water to reduce the adhesive residues and degradation products, reduce staining, and strengthen the paper. After washing the poster was dried and pressed below thick felts. The poster will be lined with a specially ordered handmade paper and wheat starch paste for stabilization. After lining and subsequent mending the tears and loose fragments will be properly realigned and the image will be safely reintegrated.