Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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lamination

A method of protecting and preserving embrittled or otherwise weak papers, maps, etc., by placing them between sheets of thin, transparent thermoplastic material, which, when subjected to heat and pressure, with or without an adhesive, seals the paper in and protects it by making it more or less impervious to atmospheric conditions. It also increases its effective strength.

The paper is first deacidified and dried. It is then placed between two layers of cellulose acetate film approximately 0.001 inch thick. Layers of Japanese tissue or lens tissue are then placed over the film. The "sandwich" is then fed through heated rollers under pressure, emerging as a sheet slightly thicker and heavier than the original document and considerably stiffer and stronger.

Lamination is an excellent method of improving the mechanical strength of documents which are to receive considerable handling, but it also has both real and potential disadvantages. Unless the document is properly and adequately deacidified before it is laminated, it will continue to deteriorate despite the illusion of protection afforded by the laminating film. In addition, there is the slight but definite loss of clarity and sharpness of the printed matter, especially in the case of colored illustrations. It is also difficult to remove the document from the laminates. See: DELAMINATION (2) . Finally, there is potential damage from the cellulose acetate itself, which may be more vulnerable to the action of the atmospheric gases such as sulfur dioxide, particularly if the acetate contains metallic impurities. See also: BARROW, WILLIAM J. ; LAMINATING FILM ;SUNDEX PROCESS .

(33 , 35 , 72 , 173 , 198 , 218 , 303 , 364 )




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