Info on seam sealing silpoly needed

Permatex flowable silicone from the auto parts store works great. I like to dilute 3:1 with odorless mineral spirits. Use a small foam applicator brush from the paint section at Lowe’s.

Don’t use odorless mineral spirits, use the real (stinky) kind.  I used odorless many years ago and it worked fine, but the most recent odorless I tried were not the same thing at all.  Before sealing my last tent I mixed up a test batch with the odorless spirits and it made a sloppy mess.  The cup of it stayed liquid for several weeks–yes, WEEKS.  If I had painted that on my tent it would have ruined it.  Don’t risk it; find some good ventilation and use the real stuff.

For seams, just get some silicone caulk (100% silicone….usually by GE.) I usually use about 1oz per 6-8oz of mineral spirits. (Get real mineral spirits, not low VOC stuff. Or you can use white gas/Coleman fuel but it dries very fast.)  Spread on with a finger or a very small brush (like 1/4″) over the seams. Usually on both sides. It is not as neat as thicker stuff, but works as well.

Note: For a 9×9 tarp (9sqyd) I usually mix up about a quart and do the entire tarp. You are often better off doing this after some initial stretching of the seams, ie, use it a couple times. I use a 4″ bristle brush or a cheap “chip” brush. When I am done it will add about 2oz to the entire tarp. Roughly you can calculate that by the ammount of silicone caulk you add. I use a thinner mix, around 15:1 for the entire tarp. Yes, it will seal the seams, OK. I also use a folded hem and rolled flat seams.

I have seen two types of odorless paint thinner.

The one that works says “made with mineral spirits” or “ingredients: mineral spirits” and says it’s flamable.  Maybe it says “lower VOC”, not odorless

The one that doesn’t work says it’s better than regular mineral spirits and isn’t flamable

Another product that’s mineral spirits is barbecue starter fluid

Make sure and test a little bit of silicone:mineral spirits and make sure it mixes and dries

Do you really need to seal your seams?  I never seal my seams on my mids and they never leak, but mids have seams with steep slopes so maybe that’s why they don’t leak.

Thanks for all the great info , was unable to respond was on short trip hiking Ocala FL. Freezing ,.   Did find out tarp leaks alittle at pull outs so Will need to definitely seal