Correlation of Simulated Rainfall Tests with Laboratory Penetration Tests

Abstract

Research and Development BranchIn an effort to establish a relationship between the length of time a garment will keep the wearer dry and laboratory tests of the fabric from which that garment was made, the study described in this report was undertataken. Since the rainroom has been recognized as a valid testing device, a correlation between rainroom results and data obtained by the much simpler and more economical laboratory tests should in most cases furnish an accurate method of predicting the performance of a garment under conditions of actual wear. This study shows that it is possible to estimate from the results of laboratory penetration tests the most probable rainroom protection time of a fabric treated with a durable water-repellent compound.

A Theory of Water-Resistant Fabrics

“…for the ethanol-methanol used), and P is the observed air pressure in dynes; cm.2. The apparent contact angle was calculated according to equation (5).…”

“…( 1 ) Cotton fabrics woven sufficiently tight, such as the Quartermaster fabrics described by Landsberg, Kelly, and Sinski [5], are superior to the best woolen fabrics, whereas, according to the Baxter and Cassie theory, tight weaving of fine yarns should lead to close fiber spacings, ease of interfiber film formation, and early failure of the fabric.…”