shortly I'll be ordering some "soft" tyvek for a tent footprint. I intend to treat both tent and F.P. with a Permethrin soaking. now I assume that the ultimate would be if the insect repellent was absorbed. but there's not much absorption with the types of materials used in modern day camping fabrics. and I suspect that near zero for the tyvek. would a soaking of a week, force the insect repellant deep into the fabric? or is the best I can expect is to coating on the surface?