Werner J. and Gisella Levi Cahnman Preservation Laboratory
The Werner J. and Gisella Levi Cahnman Preservation Laboratory is dedicated to stabilizing, maintaining, conserving and prolonging the shelf life of the Center’s extensive and (in part) deteriorating paper-based collections. The Laboratory deals with dozens of individual items on a daily basis, reformatting brittle materials and collections, microfilming materials for seamless access and retrieval, treating items damaged by use, preparing items for exhibitions, and preserving and storing collections in proper containers and wrappings.
In applying basic preservation treatment, depending on the condition of a particular item, one or more of the following techniques might be used either separately or in sequence:
- Flattening
- Cleaning
- Mending/Repair
- Deacidification
- Encapsulation
Flattening
A crumpled, folded, wrinkled, or creased paper item must be flattened through humidification before any preservation treatment can be applied. The item is placed in a humidity membrane envelope and secured with paperweights. Through a paper bladder which rests on top of the humidity membrane, using a water air pump, a fine mist of distilled water is evenly sprayed over the envelope. After some time, when the paper relaxes, we can proceed with necessary preservation treatments.
Cleaning
An eraser powder is spread over the area covered with a film of dust or dirt. By moving one's fingers (wearing cotton gloves) gently in a circular motion, the dust is absorbed by the powder. To prevent further damage to the text, one has to be aware of rips, fading ink, or pencil writing. The soiled powder is removed with a soft brush.
Mending/Repair
A thin strip of heat-sensitive adhesive tissue is applied on the back of the page with a warm spatula. The heat is applied through a silicone paper buffer which further prevents the document from absorbing excessive heat. When the rip or tear is extensive, the heat tissue is applied from both sides.
Deacidification
A thin mist of "Bookkeeper" deacidification liquid is evenly sprayed in layers over the paper item and allowed to dry. To measure the impact of the treatment, the PH (acidity) level is measured before and after the treatment.
Encapsulation
This technique is employed when handling fragile, oversized paper items such as posters and unique documents. After an item has undergone full basic preservation treatment, it is placed in a Mylar sleeve, enclosed with two-sided tape, allowing for air circulation. Depending on the fragility of the paper, the item maybe reinforced with a buffed backing tissue, and placed in a .003 or .005 thick Mylar film.