Washing them strips the outer proofing in one go, you pour the stuff into a sink with water and wash by hand, it does not effect breathing, Gore-tex still has its waterproof membrane but as soon as the outer layer gets wet the breathability stops and your jacket brethes like a bin bag! Instructions are on the bottle.this is the stuff
http://www.fieldandtrek.com/sfile/1/filt...h-In-750859.htm