Seam Sealing a TarpTent

[Jim MacDiarmid]

I have a TT Rainbow and I need to seam seal it. This is a newbie question, but do you seal the seams on the outside or the inside of the tent? Or is it just a matter of aesthetics

Thanks.

[Charles Grier]

I have always done the seam-sealing on the outside. I suppose you could do it on the inside but I would worry about water getting through the exposed stitching on the outside and then doing bad things once it got through. Just like patching a leak in the roof of a house; you always work from the outside.

[Dan Cunningham]

Charles's comments x2

[Jim MacDiarmid]

Thanks for the speedy responses. I was starting on the inside, and then had the thoughts you enumerated. I didn't get too far fortunately.

[Roleigh Martin]

http://www.tarptent.com/faq.html

Q: Do Tarptents need to be seam-sealed?

A: Yes, it's a good idea to seal the the seams along the rear arc and the pullouts to protect the stitching. The ridgeline seam can also be sealed but has proven to be extremely water resistant without sealant. Silicone is the only material that will stick to the fabric. Urethane sealer will flake off. An inexpensive product that works well is GE Silicone II clear sealer/glue. It is available as a squeeze tube in most US hardware stores or in the Tarptent Store. Set up the tent ouside in a in a well-ventilated location. Mix about a tablespoon of silicone with a couple of tablespoons of mineral spirits(paint thinner) and then apply the solution with a small foam brush. Add more mineral spirits if the solution gets too thick. Avoid skin contact and breathing fumes.

Use those 3/4" throw away foam brushes (40 cents), stir the mix until it has an enamel paint consistency. the advantage of this degree of liquidness is that the solution will penetrate the fabric making a much better seal, — put the tent out for 3 days, on second day, do any touch up, as sometimes the fabric absorbption leaves "room" for more to be "foam painted" on the second day.

I did my tents this week. A good seal will hold for at least 2 years if not more.

The pre-mixed sealants at REI or a sporting good store are complete junk for the reason they are too thick and tend to only stick to the outside of the fabric rather than penetrating the fabric, even though the ingredients are probably the same.

It is important you add enough mineral spirits to get the liquidness of a paint.

ps. Because the mix is very liquid, when you seam seal from the top (outside), the sealant will permeate and penetrate through the fabric, so it is sealed all the way through the fabric. However, double check the sealing the next day, this permeation can cause the surface you seam sealed to look "not enough" the next day, because of that dispersion throughout the fabric and you will see in about 10 percent of the spots that you should have used more, which you add day 2.

[Jim MacDiarmid]

Roleigh, thanks for the detailed advice. I had read the TT instructions on how to make your own sealant, but I just went and bought Mcnett's silnet at REI. I didn't realize that should be watered down a bit too. Unfortunately, I already sealed up the tent using the undiluted version before reading your instructions. I do have a tarp I still want to seal, so I'll use the diluted method on that. Your way will probably look a litter nicer too.

I'm not super concerned though. Traveling in the Sierra in summer, I shouldn't be exposed to too many extended nights of rain where the seam-sealing would be put to a challenge.

[Mary D]

I've found that using a small stiff brush (like the one that comes with SilNet) works better to get the sealant worked into the threads. That way I was able to seal the tent better with less sealant (the sealant does add to the weight of the tent) than with the narrow foam brush. Your Mileage May Vary.

I suspect that all of us once had a tent on which we've overdone the seam sealing. I still have and use the one on which I put almost 2 ounces of seam sealer!

Be sure to test the adequacy of the seam sealing with a hose before taking the tent on the trail!

Afterthought–*odorless* mineral spirits (available in paint department) are better.

[Roleigh Martin]

Two great ideas there Mary. I wish I had read this a week ago. I probably put an added oz of weight on the tents.

On the other hand, the extra sealant does protect fabric from stress at points where tent normally suffers stress, still your solution is something I wish I had done to save the weight. I like the hose idea too however, silnylon is not impervious to super high water pressure while it might be impervious to any rainstorm pressure, is that not the case somewhat?

[Dylan Sawyer]

Can you dilute Silnet with mineral spirits?

I have the some Silnet, but before I run out and buy some flammable chemical I will never need again, I thought I'd ask.

Thanks-Frisbee

[Roleigh Martin]

You could ask the Silnet manufacturer but I'd be surprised if they advised against it. It should work just fine.

[Boozer]

Dylan – Yes you can.

[Mary D]

Having used both SilNet and the GE silicone caulk, I found that the SilNet is just a thinner version of the GE stuff. The GE silicone caulk is a lot cheaper, but if you're sealing only one tent, there will be a lot left over. If you're going to dilute the SilNet (so that you need the mineral spirits anyway), then get the GE silicone caulk at the hardware store; the tube of caulk is cheaper than the tube of SilNet.

[Mary D]

I just found an interesting product recommended on the "Lighthiker's World" blog: http://lighthiker.wordpress.com/ The author is from Germany, so this blog–in English–is great for a European perspective on lightweight gear. The product, Permatex® Flowable Silicone Windshield and Glass Sealer, comes already diluted. I checked and it is available in the US; one vendor mentioned is Ace Hardwear.

A tube of this stuff appears to be about the same price as a tube of Silnet. Has anyone used it? I have a tent coming (hopefully later this month). I have, however, enough of both Silnet and the GE silicone caulk, plus the mineral spirits, to seal several more tents!

[Dan Cunningham]

I just seam sealed my Lunar Duo and my friend's Lunar Solo today. I used GE Silicone II mixed with spirits. I got it liquid/runny enough that it would flow into the seams. I used a children's medication syringe to do the whole job. It worked way better than the brush I used on my last 2 tents. I highly recommend this method. Very clean, and I think a better seal.

[Dylan Sawyer]

Anyone think I can use actone (aka nail polish) to dilute the Silnet? I'm don't feel like buying a quart of spirits for the whole 1/2oz I'll eventually need. In any case, if no one has a response, I'll probably give it a shot.

[Rick Cheehy]

Wow I totally sealed the inside and outside of mine, oh well. I think if you use acetone the smell could linger and it might be rough on the nylon, but I've never tried it. Can you burn mineral spirits in a stove? Can you seam seal with heet? Can Seal seem hot when he sings kissed by a rose?

[Roger Caffin]

Yes, I have used it. I would not call it 'liquid', but it is a lot more runner than the hardware stuff in tubes. It seemed to work fine.

The big problem with diluting the hardware stuff (eg GE, Dow, etc) is that it does not want to mix!

Cheers

[Chris Chastain]

> The big problem with diluting the hardware stuff (eg GE, Dow, etc) is that it does not want to mix!

So true.
It WILL, given enough patience (which I lack), but is not worth the $1 savings, particularly since the huge left-over amount will invariably be cured in the tube the next time you need it.
None that I know of is mineral spirit based (it smells like vinegar). Talking the aquarium type RTV clear silicone here… there are so many different formulations now (even "paintable"!) it's hard to be sure.

The Silnet brand IS mineral spirits based, so it mixes MUCH easier when thinning. It is not just a thinner version of G.E. type caulk.

If you smell the Silnet, you will recognize the odor of Zippo lighter fluid. This is naptha, which is usually sold next to the mineral spirits as V.M. & P. Naptha. Such a small amount is needed that a small can of Zippo-type lighter fluid should suffice.

This stuff dries quicker and (in my opinion) has a less objectionable odor than regular mineral spirits (either the odorless type or otherwise). As always, YMMV.

[Dan Cunningham]

Roger – you are correct, it's not an instant mix. It took 3-4 minutes of constant stirring to get a nice smooth consistent solution.

[Greg Mihalik]

Silicone and Mineral Spirits
Deep narrow container
Variable speed drill motor
8" of coat hanger bent into a 'J'

It will mix.

Pour it into a syringe body and apply.

Acetone will evaporate to fast to be useful, plus it's hard on your kidneys.

[Diplomatic Mike]

I just sealed my DuoMid yesterday. I used about 1/2 a tube of SilNett mixed with 2 or 3 times the amount of white spirit. I use the kind of white spirit you get in paint stores.
I don't think the ratio is too important, as i've sealed a few things using this method without any problems.
I use a thicker mixture for lines on a tent floor to prevent slipping.

[Gordon Smith]

Anyone know if mineral spirits have a shelf life once opened? I have a can of mineral spirits that was first opened a year ago. I just got a Tarptent Contrail that I need to seal but I'm wondering if I should buy a new can of mineral spirits first. I know gasoline can go bad in a year. My tube of GE silicone is fresh.
Thanks,
Gordon

[Dan Cunningham]

Gordon – your mineral sprits should be just fine. I don't know what the shelf life is, but it's really long. I just used a container I bought over 5 years ago.

[Art Sandt]

Gasoline needs to burn cleanly and consistently in order for your car to run without problems, so it's held to a pretty high standard with regard to "expiring," which is mainly to say that over time, some of the gasoline in a gas storage container will react with the oxygen in the air and produce compounds not ideal for burning in an engine. Also, the more volatile compounds in gasoline tend to work their way out of storage containers and sometimes water can work its way in, so an engine trying to burn this concoction *might not* run as smoothly as it would run fresh gasoline (although some storage containers are going to be more ideal than others at keeping gas fresh). Mineral spirits can be held to a much lower standard, though, and even if it were to "expire" to the same standard that gasoline is said to do so, all you need to do with mineral spirits is thin out some silicone so it should be fine.

If you're concerned, you can always mix some up and do a test with a piece of scrap silnylon or on the tarptent's silnylon stuffsack if no scrap is available.

[Chris Chastain]

Yes, mineral spirits will go bad.
The good thing is, if you are asking the question, its probably fine. There will be no question what-so-ever, if you ever open and smell mineral spirits that have gone bad.

It takes longer than gas, but bad gas is really bad.
It basically turns into thick, gummy varnish that will render a carburetor inoperative until completely disassembled and cleaned… fuel tank too. It has an odor that you will never forget, and if you spill it, the smell will hang around for a long, long time. Very similar to the smell of mineral spirits that have gone bad.

To get to the point… if it smells like mineral spirits, it's fine.

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