Well…not really a procedure. I have done a few tarps, tents, boat skirts, jackets, stuff sacks, etc.
If it is around 40F, you can use white gas. It will evaporate quicker. Basically, you want the solvent to evaporate before the silicone sets. Use the solvent to simply carry the silicone into a thin film into and over the fabric. For raw fabric, it will penetrate into the threads, bonding itself to them and itself making it stronger. So, it works fairly well for older tarps that are stretched, or, sun damaged. It will replace some of the lost strength.
I use a 3″ brush, fairly thick, bristle. I know I will need to clean it out again, later. NEVER use this brush for anything else. The silicone will have a bad effect on varnishes, wood, paints, etc.
For new nylon:
Roughly, I use about a 1/3 tube of 100% silicone caulk mixed with about a quart of mineral spirits. 3oz:32oz by volume for new untreated nylon. Mix slowly, adding a little mineral spirits at a time, mixing it in and reducing the overall thickness. When it mixes easily, add the remainder. Stretch your nylon out and coat BOTH sides. Usually, the first coat will have dried out some, or wait till it starts to look dry before doing the second side.
The first side is brushed in hard, with an almost circular motion to penetrate everything. The second coat is mush easier, just brush it on and cover the area. It should discolor as you brush it on. It will lighten up again as it dries.
For already treated silicone, I dilute the 10:1 again with more nineral spirits: ~15 or 20-1. For seam sealing I use the above mix. For old rain jackets that started leaking, I use the above mix. For dry bags, etc, I simply coat both sides. Note that it does NOT work with PVC, but will usually stick to the nylon side of a nylon/pvc item. You cannot repair a PVC coated floor with it, but you can do a silnylon one. You can use this several times, so a low head silnylon flooring can be coated to 5000mm or higher for less weight than PVC. It will add about .2oz/yd for each coat if done properly. Do not leave puddles and other excess on the fabric.
If applied thinly, multiple coats will not usually peel off. Peeling happens when the silicone film is stronger than the bond to the fabric. So, thin is good. Too thin and you can see spots that look like water beads on the surface. Too thick and it will slow the coating process, it will feel sticky on the brush.
A tub will only last about 24 hours. After that, the silicone will bond to itself leaving a gelitinous mass. It will NOT work to coat anything. So, make as little as possible to finish the job.
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