Paper puncture tester: a new instrument for facile evaluation of paper strength

A simple apparatus for evaluation of paper strength is described. Determination of the depth of puncture (P) of a metal spike into paper is evaluated, which causes only limited damage to the sample. A measurement of paper thickness is also needed. Determinations of puncture resistance of a representative group of paper from a library collection were correlated with the number of double folds (DF). The obtained correlation enables easy categorisation of papers into risk groups according to their mechanical properties.