Silicone and Mineral Spirts Problem

I know this is an old thread, but it's a useful one as it was all I could find on this issue when I had a similar problem.

I've had my homebrew seam-sealing go this way (greasy, slimy, oily, not drying) twice now.

In both cases, it just took two-three days to dry. Which is excessive and unusual compared to what it normally should take, but if you hang in there and wait, it'll still be functional. If you can't wait, maybe try a hairdryer.

When I first did home-made seam sealant, I followed Henry Shire's instructions for my Contrail, and the results were great.
Here is Henry Shire's video on the topic:
http://www.tarptent.com/ttvideos.html#seamseal

In this video, Shires uses Sunnyside paint thinner.
In both my last attempts, I used Klean Strip Odorless Mineral Spirits, and I believe this was the problem. It was about a year or two old. That may have been a contributing factor. I used two different silicones (the second time, brand new GE Silicone II).

The best advice I can give that I didn't take is: plan ahead and test your batch before putting it on your tent.
The next best advice I can give is: don't do this on a windy day! Don't ask me how I know this.

At Tarptent Nevada City they have been seam sealing several hundreds of shelters a year for several years.
If there was a problem with the way they do it it would have been obvious by now.
So my suggestion is to do it EXACTLY as they do and by that I also mean to use the same stuff.
Mind you I have done over two hundred myself and here in Australia I use standard Mineral Turpentine (NOT the odourless type…), that works well too.

yeah, same here, odorless paint thinner doesn't work. It's sort of watery rather than petroleumy.

There's a product called safer paint thinner that works pretty much the same as regular.

Yeah, best to try it first, make sure it dries properly.

When I was reading up prior to seam sealing a silnylon tarp, I read that there are two different chemicals, both called "mineral spirits", and that the "odorless" type did NOT work for seam sealing with silicone.

So, just get the "regular" mineral spirits, and it should work fine. I just seam sealed the exterior seams of a MYOG X-Pac backpack, and there is no discernable residue (although, to be honest, it smelled really strongly for a couple of days until the mineral spirits residue wore off!).

Yes, there are actually more than 10 types but I won't go into all that. For turpentine, this is an old fashioned naval product. It was made from pine trees usually, Southern Yellow Pine notably. It is a natural product in most pines to some degree. This can be used but is slow to evaporate and should only be used at fairly high temps where mineral spirits evaporates too fast to work with.

Mineral spirits are various distilled petroleum products. There are many different grades from oily to almost benzine like, evaporating quickly. I usually us Kleen Strip Mineral Spirits. I think it is marked as low odor or odorless…fat chance, it has a strong smell.

Eco-Friendly stuff I don't use. It will thin paint up to about 10%. It does not do so well with silicone caulk often setting it up as you brush it on. It just doesnt stick or penetrate into fabrics and washes off with a little soap and water. The caulk requires water to set. Eco-Friendly stuff has water in it.

White Gas can also be used at low temps, around 35-45F. It evaporates fairly fast, leaving a thin layer of uncured calk. This is good. Depending on the temp, this is what you want mineral spirits to do, also. Evaporate while leaving the uncured caulk on the seam, but not so fast that the brush "sticks", leaving you with some working time.

Regular auto gas no longer works. It has alcohol in it which also attracts water, curing the silicone before it evaporates. This is part way between mineral spirits and eco-friendly stuff. It does not stick as well or may have a few lumps in it.

Hope this helps…