Here is some technical information on Permethrin and military uniforms. There is a long history of use.
This report evaluates the "staying power" of different permethrin treatments, two roll and soak methods (initial stock 10% permethrin vs 40% permethryn) and the newest which is a polymer coating incorporating permethrin which is put on during the manufacture of the fabric. One patent I read cites polyvinyl alcohol , PVA, as the polymer.
The polymer coated method is cited as lasting through 100 washings.
The fabric is a common military (Germany) 80% cotton and 20& polyester.
http://www.afpmb.org/bulletin/vol24/Permethrin-based%20Fabric%20Impregnation.pdf
