Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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warping

The distortion of the covers of a book subsequent to binding, to the extent that the covers do not lie flat against the text block. This distortion is caused by the difference in expansion and contraction of the various components of the cover-cloth, boards board paper, and, to a lesser extent, the films of adhesive which secure these components together. Warping is found to occur in the direction of: 1) the side of the material which has the greater stretch; 2) the side of the material with the least moisture content; and 3) the side which is lined or has the greater number of layers. On newly bound books these factors are at work because of the setting and drying of the adhesives; subsequent to binding, stresses may occur because of atmospheric changes. The practical means of minimizing warping include the use of well-matured boards, cutting the boards and board papers so that the grain (machine direction) runs parallel to the spine of the book, the use of adhesives containing a minimum amount of water (and no more than the minimum amount required of plasticizer), and adequate pressing of the books after casing-in or covering. In addition, maintenance of a stable atmospheric environment is important.




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URL: http://cool.conservation-us.org/don/dt/dt3732.html
Timestamp: Saturday, 19-Nov-2011 13:18:46 PST
Retrieved: Saturday, 18-Nov-2017 17:34:39 GMT