Just seen this new cotton proofing product from Nikwax. I haven't tried it, but thought people may be interested (I am!)
[video=youtube;jTP_l4Dye6k]http://www.youtube.com/watch?v=jTP_l4Dye6k[/video]
[video=youtube;jTP_l4Dye6k]http://www.youtube.com/watch?v=jTP_l4Dye6k[/video]