Restoring silnylon (with links)

No, silicone caulk and mineral spirits does NOT peel off. Unless you are using Poly, of course. Nothing really likes to stick to poly. It can work on poly fabrics, provided they are woven and not heat pressed together. Yes, the secret is the dilution. I use about 1:15 or somewhere between 1:10 and 1:20, I do not really measure it out. You have to do both sides of the fabric. I do not think it actually sticks, but it will form a bond between all the threads, thus making a “rubber” film around all the threads, keeping it from peeling off.

On silnylon, I use the same after making a tarp for someone. Again, both sides keeps it from peeling, and, seam seals it. It only adds about an ounce of weight to a 7×9 tarp (roughly about 7 yards or around 0.2oz/yd.) On an older stretched tarp it works really well to seal up the fabric again, “gluing” the threads back together and actually reinforcing the material. Though, I tend to mix it thicker, maybe 1:10.

The silicone spray/brush treatments you buy are almost pure silicone without the “adhesive” formula used by caulk. Caulk will cure with a touch of humidity, soo, you cannot buy an adhesive silicone premixed. Any such attempt will cause the entire batch to cure into a “jelly” like consistency. Opening a can of it will do the same because moisture (humidity) in the air will effect the entire can…water acts as a catalyst and is NOT used up in the process. They cannot can it for use. The mineral spirits also delays the curing process. Anyway, the spray on stuff does not really bond with the fabrics. Rather it coats the fabrics with a silicone water resistant surface. The DIY stuff actually bonds with silnylon and the original knifed in coating. It WILL wash off after a few uses…especially at creases. The adhesive in the DIY stuff prevents this.

I really never tested the waterproofness of the DIY treated fabric, but I can say that it DEFINITELY improves the hydro-static head. My original tarp misted after a couple years and would not hold a water bubble without leaking. After treating both sides with a measured 1:20 (by volume) it looked almost rubberixed, added a couple of ounces and could actually be used to hold water. The misting stopped, of course. It will NOT stop condensation, however. In some cases, it can me worse under a DIY treated tarp than a regular sprayed tarp.

No, silicone caulk and mineral spirits does NOT peel off.

This post relates the experience of a user who had peeling issues with a homemade formula.
This response to that post suggests that the peeling might have been because the ratio of silicone to mineral spirits was too low, at 1:7.
This post by Richard Nisley states that anything higher than 1:6 won’t improve the HH.

Enjoy your day!

Yeah, I was trying to help Jerry a bit. I don’t think I have ever used a thick coat, 1:7. Again I don’t measure too accurately for this stuff, but 1:10 -> 1:30 is my usual. I add in about an ounce of GE Clear, “100% silicone caulk.” I add in anywhere between 2oz-3oz of mineral spirits. I mix this until it is a single consistency. Then I add in about 8-30oz of mineral spirits and stir until it is well mixed. The amount I make is almost always about a pint and a half, give or take. It ain’t rocket science. I apply it to both sides as quick as I can brush it on with a 4″ disposable brush. It has always stuck to the fabric and itself, in some cases it has bled through forcing me to re-brush the other side. As it cures, I anticipate that the mineral spirits evaporate quicker than the humidity will cause a cure. It doesn’t really matter though. The caulk and mineral spirits actually form a colloid. I have often had a portion left over, it will gel anyway with the long chained hydrocarbons (mineral spirits) forcing the caulk to be somewhat softer. After two weeks a portion will actually set pretty fully if you give the mineral spirits a chance to evaporate off. The mineral spirits only help dilute the caulk for distribution on the fabric and help keep the water vapour from the caulk for an extended period of time…around 3 hours, not 15-45 minutes…slowing down the cure.

Frankly, I think Richard might be mistaken about the HH of DIY treatments. The nylon fabric leaked some air bubbles and water. After treatment it did not. Again, I have no idea what the HH was. I just know it MUST have been higher after the treatment. Don’t forget, two coats, inside and out, are needed initially. The wetting properties of mineral spirits seems to dray the caulk through the fabric. After that, you only have to do a touch-up on oneside. Hmmm, it actually helped with my silnylon floor, come to think of it. HH from kneeling on it MUST have been higher because my knees didn’t get wet from ground moisture.

Anyway, have fun. DIY sealing/coating is like painting. Some people really like it.

Thanks for weighing in, James. You played an active role in most of the threads to which I linked in the OP. I was just trying to do a public service and bring all of this stuff together to help other people.

I’m really intrigued by the idea that the addition of adhesive compounds to the caulk (if you buy the right kind) which is then applied to both sides of the fabric may be the key to getting really good results. You’ve convinced me to give that a try instead of using over the counter products like Atsko or Fabsil.

FWIW, I really dig painting (as in interiors and what not).

Yeah, Painting can be fun, for me it is chore. Paint both sides as rapidly as possible, let it dry and if ut doesn’t look a little like rubberized fabric, you can always add another coat. It works fine. BTW the caulk is simply formulated to be sticky, unlike most sprays.

As one data point, I mixed a portion of the GE silicon with mineral spirits for a seam sealing job I did, and I only used about 1/3 of the total mixture. I sealed it up in one of those little mini paint cans and turned it upside down. This was over a year ago. Fast forward to a couple months ago, I used some of it to reinforce some of the weak areas on my shoe uppers. It looked as liquid as when I left it. It did take several days to cure however, so I don’t know what that was about, but I didn’t have any chunks or solid portions floating around in it. I don’t recall the mix ratio on it.

Wow, Michael! I have never gotten it to stop curing. Once any moisture enters the mix, it will continue to cure on me. I wonder if it was a very thin jelly? Likely did not seal well either?? Several days to cure doesn’t sound right. It usually takes about 3-4 hours.

Silicone is a polymer that changes properties with the type/length/branching of the molecular chain…similar to hydrocarbons and plastics. Various properties can often be enhanced by chemical changes from a goop to a “solid.” Or they can be ruined, as with silicone grease. Normally a catalyzed reaction will continue to completion, depending on concentrations.

It is not as simple as that.

Some silicone polymers do catalyse on water, and you only need a tiny amount. You might ask from where does the diluted mix get its water? From the solvent you use. It was not absolute AR lab grade stuff (was it?), so it would have contained a few percent of water. Sad, but true. Industry does not require anything better. That amount of water was enough. The sort of sealant you get in cartridges for gutters and windows is this sort. It usually goes off within a couple of months of unsealing the cartridge anyhow.

On the other hand, what you get in small tubes of silicone adhesive is a different sort of polymer, or so it seems to me. That stuff can sit in the tube (with the cap on tightly) for a year or two and still be quite good. Been there, done that, many times.

Me, I use that Permatex Flowable Windshield & Glass Sealant. Yes, they call it a sealant, but it is really an adhesive imho. I see from our local hardware store that there are now alternatives on the market, and I have tried at least one of them too. It was OK.

Why do things get all technical???

Cheers

Me, I use that Permatex Flowable Windshield & Glass Sealant.

Roger, are you using Permatex just for seams or for recoating an entire tarp or your tent? If the latter, what is the ratio that you use? I think you said elsewhere that you use Atsko spray every few years on the tent, so I assume that Permatex is for the seams, but would like to get confirmation. Thanks.

Hi Jon

Your assumption is correct. Permatex for seam sealing, and a silicone spray to ‘refresh’ the coating on the tent occasionally.

I should clarify the spray bit. It upgrades the water repellency of the silnylon, which is always good and which handles most light to medium rain, but it does not change the hydrostatic head at all.

I did recoat the floor of my blue tent once, in a hotel room in Italy (!), and for that I used a neat Italian version of the Permatex. I forget the brand, but it wouldn’t be available in USA anyhow. I smeared it across the floor very thinly. Interestingly, the remains of the tube were still ‘flowable’ and usable a year later. Of course I brought the rest of the tube home!

Cheers

Permatex is available in France, at a premium.

I’m going to go with the preferred choice of the UL forums in Germany: Wacker’s Elastosil E43 silicone adhesive.

Will be applying it to an old old old MLD Trailstar and a slightly newer Littlestar.

Wacker is a big chemical company. I suspect they supply some of the smaller ‘brands’. Well, that’s what their tech guy told me anyhow.

Cheers

Jon,
One issue that Roger alludes to is that some of the spray or canned products like Atsko enhance only water repellence of treated materials, but not water resistance (so no HH increase); while some others will actually enhance water resistance.  An example of the latter is Tent Sure by McNett Seam Grip, although with changes in product lines, I’m not sure it is still marketed.  I believe Granger’s  in the UK also markets a liquid waterproofer, but have not tried it.  I think the prevalence of threads on this subject is the natural product of hope for a quick-fix water proofer from a can; but it is not that easy, although the threads on BPL suggest many hope otherwise.

I have found that better quality repellent sprays like Scotchgard Outdoor Water Shield, do greatly improve the durability (useful life) of silnylon materials; however a careful reading of the label indicates it is a repellent only, not a waterproofer.  A more recent product, Penguin UltraDry Protecter does state that it  “waterproofs” fabrics.  Note that the Tent Sure is on the heavy side, and is probably a mix with polyurethane, and is therefore ineffective on silcoated floors.

But another big catch is which of these products have a silicone base; otherwise, I doubt they would bond to or enhance the waterproofing of a silicone coated fabric.  This requires still more squinting at the labels on the cans.

So understandably folks have turned to DIY mixes ever since the late Jack Stephenson’s flashy catalogs suggested this and other ideas.  Mineral Spirits seem to be the most popular thinner, but a number like myself have used stove fuel because I found it made a smoother mix.  Perhaps too smooth, because the person whose SMD tent I seam sealed with several very light coats complained it made the tent too steamy.  But she had not yet exposed to tent to heavy rain.

While I’ll not name any names, a number of well regarded trekkers on BPL have posted that silicone caulks thinned with mineral spirits and used on a floor eventually flaked off to some degree.  That, plus the penalty of the added weight of the DIY after-coat.   I would prefer using the best silnylon in the first place, only around 30 denier and 1.3 ozyd2, and replacing the whole floor if and when it wears out.  If the floor is DCF, as with so many superlight shelters these days, the choice of a recoat would take some researching, and since I’ve not yet surrendered to the DCF bandits, can’t comment.  But very much doubt silicone of any kind would be involved.

For sealing and patching silcoated woven materials, either nylon or polyester, I’ve had best luck with the Permatex silicone flowable sealant, undiluted and thinly applied.  Following Roger’s instructions, I’ve used the Permatex to bond sil-coated to silcoated tent fabrics for reinforcement patches, and was very satisfied.  True, the fabrics could be peeled apart by hand using maximum strength; but being reinforcement patches, there will be some added sewing involved, and I’m not too worried about the effect of heavy rain on an adhesive that is used to hold windshields in place.  I also tried Elastosil E43, and found that it was not competitive; in that the peeling by hand took little strength.

As for the demerits of silpoly vs silnylon bonding, I’d need to see someone post some evidence of that.  And don’t see what the slippery quality of silpoly has to do with it.  Plenty of silnylons, especially the thinner ones, are just as if not more slippery.

As others have done, I should mention that most of these after-coats can be very toxic.  With the exception of thin coats of Permatex, I’ve only used the others outdoors and  while wearing a MM gas mask.

In this thread from 2011, Permatex is discussed as well as Saratoga Silicone Sigillante Universale. The latter, an Italian product that seems to be similar to Permatex Windshield and Glass Sealant, is available in France for 1/3 the price of Permatex.

Just for the record, the cheapest source of Wacker Elastosil E43 for delivery to France that I’ve found is this Austrian website (10+€ cheaper than the link in the OP).

Both Wacker and Saratoga publish spec data on their products. Both are 100% pure silicone, no solvents. The E43 apparently has much higher tensile strength, at 6.5 mPA, than the Saratoga SSU, at 2.3 mPA. They have similar elongation values (approx 500%).  E43 also has a higher hardness strength. What does this mean in real world use?

Permatex has an information sheet for their product but it doesn’t provide any data on the product’s properties.

Note: Only Wacker publishes a figure for tear strength of the cured product.

Hey Sam, thanks for that long response.

One issue that Roger alludes to is that some of the spray or canned products like Atsko enhance only water repellence of treated materials, but not water resistance (so no HH increase)

You may have missed it in the OP. Atsko confirmed by email that their products do not increase HH at all, but only increase repellency. I think the thing to bear in mind, though, is that when applied to fabric that will be deployed under tension in shapes designed to avoid pooling such as a fly rather than a floor, “repellency” is enough to provide effective waterproof capabilities — up to a point. This is what I noticed, too, with first generation Black Diamond shelters made with EPIC Malibu.

Some of the products that you mention are indeed urethane formulas that wouldn’t be suitable for use on sil fabrics.

Too bad that Permatex doesn’t publish specs on their product.

Permatex do publish an SDS and a TDS on their web site.
Cheers

Did you actually download it and look at it? Those documents don’t have any of the pertinent specs that the other products mentioned above have.

Oh yeah, forgot: Cheers backatcha.

Yes, I downloaded both PDFs. I agree however that the amount of info in them is ‘not great’, but that world is very proprietary. The data did include the max temp ratings, which was useful.

Cheers

I wonder why the information gap among the products is so big? Bear with me while I do some investigative digging before arriving at a conclusion that has very little to do with published specs.

Wacker provides a wealth of specs for the product Elastosil E43 in both uncured and cured states:

Saratog’s TDS isn’t quite as detailed but still contains a lot of data:

But then you get to Permatex and there’s really nothing:

As for the properties of the cured material, nada, zilch.

Concerning temperature use range of the cured product, Permatex declares a range of -80F to 450F. E43 states a similar range, but helpfully breaks it down into two use cases, a “service temperature” (from -45C to 180C) and a “peak temperature exposure” (200C, or 392F).

Compared to the European manufacturers, Permatex either conceals data or presents it in a potentially misleading way.

Not a nice customer relations approach, but still not the key issue for this thread, which is after all about recoating silnylon products for outdoor use.

Perhaps the biggest clue comes from the composition of Permatex: it ain’t pure silicone.

Permatex contains a chemical solvent that is basically like a paint thinner and is used in the paint industry to prevent the rapid formation of a “skin” on the paint.

Reading around, I’ve learned that Permatex would thus be considered a neutral-cure silicone while E43 would be an acetoxy-cure silicone.

This might be a key difference for actual field use such as seam-sealing and recoating.

This web page comparing the merits of different cure formulas concludes: neutral-cure silicone is better for exterior use because it is more weather resistant than its acetoxy counterpart. 

Leading me to this hypothesis: Permatex works better in the outdoors because it is a neutral-cure silicone. The positive user reports would seem to jive with this idea.

Hence, the key thing for recoating and seam-sealing might be to favor silicone formulas that are neutral-cure rather than acetoxy-cure.

I suggest that the main difference between the Permatx specs and the Wacker specs is the target market. Permatex is aimed solely at the consumer market, while Wacker is aimed at the engineering and business markets. Consumers in general (don’t need)/would not understand) more detailed specs.

Cheers

I enjoyed thoroughly the technical specifications of the Permatex viscosity.

Perhaps we should ask a different question:
What specifications for the Permatex stuff do you really need, and why?

They do give max temps and an easily understood viscosity.

Cheers

I’m not in need of any spec. I was just amused by the ref to syrup. What kind of syrup? At what temperature?

If I was to perform a coating of silicon on a fabric, I’d want to know what type of solvents are present and how they might react with my base fabric. It would be low risk since it seems it has been used for this purpose already, but it I was to start from scratch, that is what I would want to know. Do we all know for certain that the solvents used in these sil sealants  do no harm to the fabric fibers?