This part of ISO 12625 specifies a test method for the determination of the wet tensile strength of tissue paper and tissue products after soaking with water, using a tensile-strength-testing apparatus operating with a constant rate of elongation.

Currently, two types of tensile-strength testers are commercially available, one where the test piece is positioned vertically and, for the other, horizontally. This part of ISO 12625 applies for both. For vertical tensile-strength testers, a device which is held in the lower grip of the tensile-strength tester, called a Finch Cup, is used to achieve the wetting. For horizontal tensile-strength testers, the soaking device is placed between the clamps.

It is expressly stated that the detection of impurities and contraries in tissue paper and tissue products should be applied according to ISO 15755.

For the determination of moisture content in tissue paper and tissue products, ISO 287 should be applied.