Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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accelerated aging test

A procedure which is designed to indicate in a relatively short period of time what will happen to materials, such as paper, ink, etc., over a period of years in storage. It commonly involves heating the specimen in an oven under specified controlled conditions. Under ideal circumstances, the material is exposed to an environment which increases the rate of its degradation without changing its nature. It is generally accepted, for example, that heating paper for three days in an oven at 100° C is equivalent in its effect to approximately 25 years under normal library storage conditions.

Although sound in theory, accelerated aging tests are, at this time, of limited usefulness. The reason is that conditions of storage, which vary widely, have a considerable influence on the degree of permanence; also, it is difficult to verify empirically the accuracy of such tests except by experiments conducted over a number of years. Such tests have actually been made, although to a limited extent. It is known, for example, that the strength of paper tends to diminish in storage, and experiments have indicated that the FOLDING ENDURANCE declines to a significantly greater extent than such other properties as tensile, or tearing, strength; consequently, folding endurance tests conducted subsequent to accelerated aging may well provide a good indication of a general loss of strength. In addition, as to the rate of deterioration, the effect of heat is very much like that of natural aging under average conditions; therefore, it is probably reasonable to assume that heat affords a practical means of accomplishing accelerated aging. (18 , 62 , 144 )




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