The wet strength of paper is assessed by taking a dry piece of paper, wetting it with a standard test fluid for a specified amount of time, and then measuring the strength. Burst testing is often used because of the ease and speed of testing. Wet tensile tests are also common, depending on the type of paper grade.
One of the rules of thumb used by papermakers to evaluate wet strength is the ratio of wet strength and dry strength – the dry on wet percentage. A true wet-strength paper grade is defined by various authors as a wet strength that is at least 10% or 15% of its dry strength. A reactive polymeric material such as polyimidomine-epichlorohydrin (PAAE, for alkaline papermaking), melamine-formaldehyde or urea formaldehyde resins (MF or UF for acidic papermaking), or temporary wet-strength of some tissue products.
Tinius Olsen offers force measurement equipment and material testing machines for wet strength testing. All testing hardware is fully complemented by our Horizon software.