A property of paper that indicates the strength it retains after it has been saturated with water. It is calculated by computing the percentage of the ratio of a paper's tensile breaking strength to its wet-tensile breaking strength. Few papers retain a significant percentage of their dry strength when wet, as the interfiber bond strength in the paper is dissolved by exposure to water. Wet-strength paper is specifically made for end uses that require a significant degree of wet strength, typically by adding materials to the papermaking furnish which shore up the interfiber bonds and enable them to retain much strength when wet. Papers whose end uses include intentional exposure to water—such as towels or labels, or maps and charts which must withstand weathering—require a great deal of wet strength.
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