Teardrops n Tiny Travel Trailers

Update on using Great Stuff to adhere the canvas to foam. After coating the canvas with 80/20 TB2 and letting it dry for 24 hours, I pulled up a couple of inches of the canvas. It still held very strong to the foam. I'm now putting a coat of PPG Gripper Primer on top of that to see if that effects the spray foam and how it works with the canvas. (I'm using the PPG Gripper, because like everyone else, I was tricked into buying it and I don't have any other use for it except experiments.)

Postal_Dave wrote:Update on using Great Stuff to adhere the canvas to foam. After coating the canvas with 80/20 TB2 and letting it dry for 24 hours, I pulled up a couple of inches of the canvas. It still held very strong to the foam. I'm now putting a coat of PPG Gripper Primer on top of that to see if that effects the spray foam and how it works with the canvas. (I'm using the PPG Gripper, because like everyone else, I was tricked into buying it and I don't have any other use for it except experiments.)

Now, you're one of those that has used TB2 before. Is it setting up as well in the cloth with the spray foam?. I'm assuming the cloth has gone stiff..

Very curious how this works out.

The great stuff made the canvas fairly stiff on its own. I didn't feel a noticeable "before and after" difference after using TB2 in the canvas.
I just checked on the experiment again. The primer dried so I covered 2/3s of the primed part of the canvas with exterior latex paint. I'm going to let it dry over night and try pulling it all off around noon. I'll let you know how it turns out.

I have used TB mixes 50/50, 75/25, 80/20. I have not noticed really anything different in the bonding to the foam. Really the only thing I have noticed is if the weather is hotter 50/50 works better and if it is colder 80/20 works better as far as application. I believe it has to do with water evaporation. 80/20 just gets too gummy or drys too fast in hot weather. 50/50 is better in hot weather, but stays real running in cooler weather. I am assuming it is something similar to fiberglass mixtures for different weather conditions. I finally just gave up and told people I use 50/50, it's much easier to explain and seems to work for everything I have done so far, cold or hot. I just deal with the runny in cool weather which is easier than the gummy/drying in the summer.

I know that everyone wants to test the bonding of paint/primer to the foam. I believe it is because they just can not believe it will work. Granted the Gripper was a great product at a great price and I am sad to see it go. But, in reality anything that will stick to the foam and when peeled from the foam pulls a thin layer of pink, or blue, with it is as good as it is going to get. There is no weak point at the glue line it is the foam itself that gives away just below the glue line. So you can have the best bonding product out there or something just barely bonding the results are going to be the same, failure in the foam just below the glue line.

With that said, there is really no need for more bonding at this point. Nothing is coming out from the foam side and poking at the canvas skin (unless you have bubbles then yes) so what little bonding there is is plenty. The only load the canvas is going to see is in shear. The real test for this is glue on a piece of canvas with enough canvas to grab on one side. Once dry grab that piece of canvas and try to pull it from the end without lifting from the surface. This is the real world test for a foamy skin.

My choice for skinning is TBII 50/50. I have applied canvas with this mix over bare foam, painted foam, primed foam. It sticks! After that I paint over it with another coat of TBII 50/50 to fill the canvas weave totally. Then I give it a sanding to knock of the high points then a coat of primer and then 2 coats of latex paint. It works!

The beauty of this is that if you do have a failure, delamination or bubbles (I have fixed both), it is a easy fix. TBII 50/50 and a small needle syringe and you fixed up and ready to go in no time. It works.

Here is a video of my foamie. It starts out just showing how strong the foam construction is and the shows the foamie in use on one of my trips. It had everything thrown at it. I have even gotten it air born a few times and yes the skin is still in great shape. Enjoy, George.

Thanks George !!! …

George, I'm following your system to apply and it includes priming the foam first, TB2 on the material. I find TB2 sticks fantastic to material or primer and only so-so to foam.. Hey, I'm just learning here, yet what I'm seeing.

RJ Howell wrote:George, I'm following your system to apply and it includes priming the foam first, TB2 on the material. I find TB2 sticks fantastic to material or primer and only so-so to foam.. Hey, I'm just learning here, yet what I'm seeing.

I do feel I get a better bond with the primer/paint TBII combo than just applying TBII to the foam. It really just depends on what I am doing. I am making skirts for #1 now and chose not to apply primer/paint to save on time plus I did not have to fair anything out. If I have to fair out the surface to make it smooth I use primer/paint in the process so to me it makes sense to paint the whole surface once I am done fairing it out. It creates a more uniform surface so you don't get weird patterns in the canvas.

Update on the Pro-cryl from Sherwin Williams.

Full strength PC only both foam & cloth worked very well.



PC to foam/TB2 to cloth applied at same time. Worked okay.. Really don't like as much.

Photo coming.

PC diluted 25% water worked very close to the full strength. Did this believing it would sink better into the cloth. Cloth does feel denser. Just topped with TB2 to see what happens.
Update: the TB2 over has no effect when applying after all else has dried. That stiffen the cloth to what I hoped to see. Sorry, this picture doesn't show the peel-back after the TB2..



TB2 on cloth only over dried PC. failed miserably..



Lastly my TB2 only, no primer involved. Sorry, but I rate it a 5 maybe 6..

Photo coming

I'm leaning towards a full priming of PC and using PC 25% on the cloth. Edit: And now TB2 over after dried.

I'll add more pictures when I can.. Imgur is not playing nice this morning..

Using Great Stuff to put canvas on foam turned out ok but not great. It pulled off very little pink foam board with it when I pulled it up. Mostly the spray foam just separated when I pulled it up. I don't think I'd like it much for exterior use. Plus, it's a lot of messy work.
I won't suggest it at all for an alternate to Glidden Gripper.

Sunday morning, 2am, I got an idea for a way to apply TB2 to make it stick better to Foam.
First I prepped the foam as always, light sanding and a few dimples put in the foam. I put full strength TB2 on it and made sure it filled the dimples and I had a very thin coat on the rest of the board.


I then took a piece of canvas and soaked it with TB2 80/20 mix. and hung it up to dry over night.


After 10 hours of dry time, the board was tacky and the canvas was damp. I took a little more TB2 80/20 mix and put a thin coat on the board. I then put the piece of canvas over it and pressed it down well with a roller.


This has been drying now for about a day and a half and it pulled just as much pink foam board as Glidden Gripper.


I think that the key to getting our best adhesion is to coat the foam and the canvas first, whether it's with TB2 or primer and letting it dry for a short period of time, then using a little more glue or primer, and then put the canvas to the board.

Dave

Thanks Dave , That’s Great !!! Sorta like pre- gluing for woodworking …

I remember when I did mine that I would roll TB2 on the canvas, then the foam, and another coat on the canvas because the first coat had been absorbed. I applied the canvas and the topside was still dry so it got another coat of glue.

The key to a good canvas application probably involves avoiding starvation of the glue joint. Precoating the canvas would help if that's the case.

Test board for Pro-Cryl is up. This is pre-primed and dried, then 90/10 mix on canvas. This board will give a 5 week sampling of adhesion.

Thanks RJ, we certainly look forward to your long term test results !!! Thanks !!!