The number of folds which a specimen (usually
paper) will withstand before failure, under
controlled conditions in a specified instrument.
In the usual test, a specimen is subjected
repeatedly to double folds through a wide angle
while under tension.
Folding endurance is a very important indication
of the durability of archival papers. The test is
usually conducted in an environmental room. A
decline in folding endurance is the most sensitive
indicator of aging and deterioration of paper. (17 , 62 )