accelerated aging test

A procedure which can indicate in a relatively short period of time what will happen to book materials, (paper, ink, etc), while in storage for a long time.

Commonly involves heating a book in an oven under controlled conditions. Under ideal circumstances, the material is exposed to an environment which increases the rate of decomposition without changing its nature. Generally, heating paper for three days in an oven at 100 degrees C is equivalent to approximately 25 years under normal library storage conditions.

Although sound in theory, accelerated aging tests are currently of limited usefulness. Storage conditions vary widely; also, it is difficult to verify the accuracy of such tests except by lots of experiments conducted over a number of years. Such tests have been made, but to a limited extent. The strength of paper tends to diminish in storage, and experiments have shown that paper's folding endurance declines more quickly than other properties, like as tensile, or tearing, strength. Hence, folding endurance tests PLUS accelerated aging tests may provide a decent indication of a general loss of strength.

Also, 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.

some information found at:
Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology
http://palimpsest.stanford.edu/don/toc/dontoc-a.html

Simulating long-term storage of a product by using extreme conditions is a common practice in many industries. It is particularly important in the pharmaceutical industry for determining expiration dating of drug products. This is usually called stability testing.

Because of the tremendous cost in time and money required to develop a new drug, it is important to get it to market as quickly as possible so that these expenses can be recovered while the product is still protected by a patent. As a result, regulatory agencies such as the FDA have developed guidelines for doing accelerated testing so that a drug can be approved for sale without real time data confirming the expiration date. This can prevent huge delays if you happen to have a product with a five year shelf life.

A stability study on a pharmaceutical product essentially involves repeating quality control testing at regular intervals and using statistical analysis of the data to determine the longest acceptable shelf life that will ensure the safety of the product. Things that can affect the shelf life include:

• Type of container (glass ampule, plastic bag, glass bottle, etc.)
• Temperature
• Humidity
• Light exposure
• Sterilization process used (autoclave, ethylene oxide, gamma radiation, etc.)

A real time stability study involves samples stored at the conditions specified on the label (eg. Store at room temperature protected from light.) for the entire shelf life or longer. Accelerated studies are started at the same time. A room temperature (approx. 25^oC) product with a three year shelf life might have studies at 30^oC and 40^oC for shorter periods of time. A product that is intended to be stored in a freezer would generally be tested after a period of days refrigerated and/or at room temperature. Solutions in semi-permeable plastic bags might be tested at low humidity to see how quickly the drug concentrates as water is lost (sometimes drug degradation can offset this concentration effect). Photostability studies are also performed in which the product is exposed to tremendous amounts of ultraviolet and visible light to see if the drug degrades. In some cases the FDA will approve a product with a shelf life of a couple of years based on as little as three months of accelerated testing. The drug company then sends regular updates to the FDA as the real time study progresses to show that the product will be safe at the intended expiration date.