Anyone ever do their own waterproofing treatment?

I've been thinking about using the Dharma Trading PFD nylon to make a fun colorful tarp, then applying some kind of waterproofing treatment to it. Any recommendations for one type of treatment over another? I've only ever used shoe-store brand sprays for boots, so any insight would be appreciated.

Obviously they could work, some of the time. Most spray on waterproofing allows misting. Almost all of the rest allow full size drops through. Some folks have made a silicone/mineral spirits mix to DIY some silnylon, but results have been mixed. The heavy ones were waterproof and the lighter ones were prone to leaking with wear. If you have time to test it would be awesome to see some real objective test results. If you don't have time to test I would say go the DIY silnylon route and make it heavy, but durable! (If the silicone is on too thick it will Peel off)

i did this last year i took some untreated 1.9 ripstop and soaked it in a silcione/mineral spirits bath then hung it in the atic to dry, so far so good. i tested it out and had some dampness along the ridge line, but i think this was due to me not haveing a water break in the ridge line. also i made/sewed the tarp first then treated the whole thing at one time.

I made a DIY tarp of a super lightweight fabric found at WM. Ended up weighing as much if not more than a silnylon would have. The first coating of silicone/mineral spirits was sponge brushed on the hanging tarp. 2nd coating was added using the same method, better but some misting. The 3rd coating was applied by mixing the S/MS in a 5 gallon bucket and dipping and soaking the tarp in the mixture then draining the excess and hanging the tarp to dry. Finally a better coating but still some light misting. Plan on spending considerable time in mixing the silicone into the MS.

the silicone/mineral spirits works great. It's like 1 part silicone and 4 parts mineral spirits, and I measured using the weight ratio. Had to reseal our tarps last fall. I'll need to double check that ratio.

Here's a tarp for the ground that I made with DIY sil:

http://www.backpackinglight.com/cgi-...hread_id=74355

There are other threads on this site about making your own Silnylon, if you do a search they will show up. Interesting reading.

I love Dharma, I am always buying something fun from them. They are also helpful in telling me which product to use for a specific application.

Yeah, I mean I could always go with something that's already waterproof, but then I'd have to use paint or something less fun than dye to make it cool. Also, I have this idea of light shining through the colors of the tarp and casting neat colors underneath.

So the 1:4 silicone to mineral spirits mixture makes for a not too heavy coating? I don't mind a little bit of weight as this wouldn't be used for backpacking, more for car camping/summer picnicking and maybe over the boom of a sailboat, but of course the lighter the better.