OK, so I finally got around to reading this thread and I'm quoting a whole bunch of folks, so hang on tight, here we go!
I'm in the process of doing some self-waterproofing tests. My only issue with the DIY silicone mix is that I think it'll be incredibly time consuming to do a large piece of material. Just got back from a 3-day hike but I'm hoping to get back to my tests soon.
I finished with my wind pants last night. I used a pajama bottom pattern and some 1.1 from Wally world. I wanted to make a pair that is less than 3 ounces and maybe waterproof. I was going to try to get a blender at Goodwill, but they didn't have any. So instead I took a Glad ware container and cut a hole in the lid. I inserted a "T" made out of plastic in the hole. The "T" is plastic scrap from work. You could use a paint mixer for a drill. I then attached a drill to the protruding end and mixed away. This worked very well for mixing it although it still took some time. I could see though the clear plastic once the bubble went away that all the silicone was dissolved. Then I used the same container to dip the pants. It made my hands soft and slippery. I suggest good ventilation. I did it at work and there were some complaints from the little indians that it stinks. I told them this is very important for the company and they should pay it no mind. I was able to clip the pants open at the top and as it was drying I pulled the legs apart. After about 15 minutes they started to get rigid and would stay open. After one application it added about .4 ounces of silicone to 2 sq yards of material. I ran water over it and it ran right off. I then ran water over it with a paper towel on the inside and after a little time the towel got a little wet. So I soaked it again in the Sil mixture this time absorbing it all and hanging it to dry. It dries very fast. After it was dry it really felt like sil-nylon. But, it still didn't pass the water test. The final weight was 2.8 ounces so I added .8 ounces of silicone to 2 ounces of fabric. I was only trying to make wind pants for an upcoming trip to the desert, but I had delusions of grandeur and was hoping for light weight rain pants. They would work for light rain but you would get wet in a down pour. I really don't hike in rain pants anyhow so they would work for camp and keeping warm. They will work real well as wind pants. The wind pants I was looking to buy cost $70+ and these cost me about $6. I didn't perfect it well enough to make a tarp though.
So really I'm hearing from Dutch that this would work great for a Tarp (No direct contact with the wet fabric) but not for doing pants or even a jacket...
That's too bad. I had some ripstop pants that I was hoping to coat in this manner to use as light weight rain pants.
Since I have had a chance to use the windpants I am wondering if my procedure isn't flawed. I was trying to make windpants that would double as light rain pants. I don't really hike in rainpants unless it is very cold. I did use the wind pants in the Grand canyon in snow.
After I got through the snow I checked and my pants were wet from the knees down. I can also breath through the pants so it wasn't a real surprised. But I wonder if I were to repeat the process and recoat them that there would be a point that they would become waterproof. As is I would need to do better if I wanted to make a tarp. I hear great success in that application. I depend far too much on down to be getting wet. They are light and doe hepl with the wind. I didn't use them much but they were so light it was nice to know I had another layer if i need it. Also the fabric i used was the tranlucuent 1.1 psuedo rip stop from the $1.50 bin that is too thin to hold very much silicone. In any case I am not making a real conclusions after my first attempt and will try this for something else in the future.
I wonder if you could force the silicone through the fabric with a squeegee or some such. I don't even know if that is possible or if it would make any difference. Maybe if you sprayed the fabric with silicone waterproofing first it might help the mixture bond better. Silicone only seems to adhere well to silicone.
...and there came to be a day, all too soon, that I became aware that I could travel no more on my long journey. Though I did not arrive where I had planned, I believe that here is exactly where I am supposed to be...
T-back you might be on to something. If you put a frame of 1x1's together you could tack the fabric like a painters canvas. Then squeegee the sil mixture on both sides of the fabric. kind of like silk screening a t-shirt. Although you would end up wasting the fabric edge's.
No one has mentioned using silicone spray or a Camp Dry type product, is this because it wouldn't be durable? Would it completely waterproof a non-waterproof fabric? The reason I ask is, we have a local chemical recycler where I come across lots of silicone lubricant and waterproofing in spray cans.
If the spray option gets shot down, I can also get free tubes of the caulk and jugs of Coleman fuel. I still have a free option, just a much messier one. And I don't mean a French Canadian.
I used the sil spray cans to give a piece of untreated fabric what is more of a DWR coating. Not waterproof.
My knife is so sharp it cut the sixth finger off my right hand! On the plus side, Inigo Montoya no longer hunts me.