Repairing the tarp, step by step
OK, I finally got around to repairing the tear in my tarp.
Before I began (not pictured) I cleaned the inside and outside of the tarp with denatured alcohol. The tarp had been used at Philmont Scout Ranch a month ago, and in spite of being rinsed clean, it was still a little dirty, so this was a great first step. Based on my experience with fiberglass, a repair can never be better than the cleaning and preparation.
For marine applications, I never use silicone as a sealant, for reasons not applicable here. However, 100% silicone has no UV inhibitors, and in fact degrades with exposure to UV. But as this is a silnylon tarp, it is the appropriate and necessary product to effect the repair. As recommended, I used GE Silicone II.
I started on the inside, and applied silicone directly to the tarp, covered it with a patch, and began working the silicone across the inside of the patch, creating a seal. This first time, I used a little too much silicone, so I used some of the excess to seal the outside of the patch as well.
I spread it across the entire patch and carefully removed the excess. In retrospect, if I had 100% covering on between the patch and the tarp, there should have been no need to coat the outside of the patch with silicone.
I flipped over the tarp, and began working on the outside patch.
Using a little less silicone this time, I applied to the tarp before covering with the patch.
As I had on the inside (but forgot to take pictures) I carefully used the spreader on the patch to even out the silicone, squeezing out any excess to the edges.
When I was finished, I ended up with a small light spot on the lower left. This was either an air bubble or a “dry” spot where there was no silicone (or more likely, a little of both). I carefully worked the spreader from the center toward the light spot squeezing the thing layer of silicone to fill the spot. Then I used the excess to cover the entire patch.
After which I covered with wax paper and weighted it with books.
The instructions say to avoid touching for 24 hours, so I will let it all sit that way until tomorrow after work before I remove the weights. Even then, since it is air tight, I may need to let it “air out” to fully cure. We will see tomorrow.