06-02-14, 06:57 PM
I think the problem with silicone spray is, although it's very waterproof, it's not breathable, and so would significantly reduce the performance of Goretex etc. Nikwax used to do 2 different waterproofers - one for breathable, and one for non-breathable clothing. Possibly they might just do one for all fabrics now. I don't know if silicone sprays would do any harm to fabrics, but don't know of anything other than tents that are treated with it (silnylon for instance) - which suggests they'd be ok.