Canvas and Foam

[Shirestone]

So I am a little new here so I apologize if this has been covered already. I have been reading through tons of existing posts but can't seem to find what I am looking for.

I have been testing out the PMF (poor man's fibreglass) on some pink 2" thick XPS pink foam insulation (Foamular). I can't get it to stick no matter what I try. I have been using titebond II in many different formulations. 50% TBII 50% Water, 80% TB 20% water and 100% TB II.
I have read many articles about scuffing up the foam using sandpaper, also tried using isopropyl alcohol to clean the surface, also tried pock marking the surface with a wallpaper tool. All this but still I don't believe to be getting the canvas to stick as well as I would expect.

When I read a number of articles on this site, they indicate that the canvas should pull off and pull with it tiny pink particles from the foam. Mine does not. I does stick but I feel like it should be sticking much more solidly.

I am using 8 oz drop cloth from the home depot for my test pieces right from the bag. I haven't tried washing them (maybe that will be my next try).
I have also tried painting the foam first with latex paint prior to gluing the canvas but still doesn't seem to help.
Generally my method has been:
1) Isoproply to clean the foam
2) pock mark the foam the aid to the glue sticking
3) sand the foam lightly and dust off completely (making sure the surface is clean)

I have tried all combinations of 1,2 and 3. Switching up the steps and removing some steps. Still no sticky.

4) I then spread the TB II and water mix on the foam.
5) I then add TB II and water mix to the backside of the canvas...the side that is going onto the foam.
6) I then apply the canvas using a roller to make sure it applies to the foam smoothly.
7) I have also tried adding the TB II and water to the front side after it is applied to the foam

All these attempts and still not sticking well. Maybe I am expecting too much sticking where there just isn't. Am I supposed to paint something on the foam first? I have tried latex paint as I mentioned but that didn't do it.
I have read a lot about Glidden Gripper but my understanding is that this is no longer made. I would like to stick with TB II mix if possible but am open to anything else at this point.

Thanks for all your help. Learning a lot from this site.
Cheers.

[Philip]

Did you remove the plastic film from the foam? All foam has a plastic film on the printed lettered side of the foam.

[Shirestone]

Did you remove the plastic film from the foam? All foam has a plastic film on the printed lettered side of the foam.

I don't believe my foam has a plastic film as I would have surely noted this when I sanded and pockmarked it. Although I will check to be sure. I also tried to apply to either both sides of the foam.

[JazzVinyl]

When I read a number of articles on this site, they indicate that the canvas should pull off and pull with it tiny pink particles from the foam. Mine does not. I does stick but I feel like it should be sticking much more solidly.

Hello Shire....
How long do you let the glue dry before determining the adhesion?

Could take several days for the glue to dry really well. Also, you CAN peel off the canvas if you lift the edge and yank. The strength comes in that the whole piece has the canvas and is wrapped around the edges by 2 inches. Use raw canvas (not waterproof, not pre shrunk). Raw canvas shrinks as it dries, holds things together, like a tight sock,

Suggest watching the George Coe video tutorials:

https://www.youtube.com/watch?v=NeR6WVAlenk


Cheers!

[Shirestone]

I have waited a number of days but still the same.
I have watched the George Coe video prior to this as well. It's very informative ...that was my starting point when I first started this.
Yes it is raw canvas that I have applied from the home depot. The only difference is that George is using 10 oz whereas i have used 8 oz. Not sure if this would make a difference or not.
I think you are right in that once it gets a 2" wrap and overlap then it will behave as a complete skin. I just figured that I would see tiny foam bits when I peel it back and I don't.
Thanks for the input.

[Postal_Dave]

I have done this test numerous times and have posted pictures of the results. You may be able to look them up under my profile.
Anyway. I've never used the Isoproply cleaner. I just make the divots in it, then a light sanding. I then sweep and blow off the dust. This gives more area for the glue to adhear to. I also only use 100% TBII to attach it. Then let it dry for at least 24 hours, maybe more depending on humidity. Do not try to make it dry faster by putting it in the sun or something like that.

BTW: For doing experiments before starting on the camper itself.

Good luck

[Tyrtill]

Here are my tests. I believe I gave the foam a light sanding and wiped down with isopropyl 90% alcohol. A very important step is to wait for the alcohol to dry probably 5 to 10 minutes. If you don't let the alcohol dry you get a very poor bond.



We've determined that titebond II does work good enough, but not great.

[JazzVinyl]

I think the water spray, while rolling down the foam is very important!

[GPW]

A damp canvas will stretch for application , and will shrink tightly when dry to form a “sock“ on the foam …

[ghcoe]

These is the results on my last build. I had to make the window opening a bit bigger on #3. I cut the canvas to remove it before trimming back the foam.

In this case I am pulling the canvas off of the exterior of the trailer. On the exterior before applying canvas I spackle and then apply a coat of primer. This is probably about a week after applying the canvas. You can tell that the primer/canvas is indeed pulling a pretty good amount of pink off the foam.

With Primer

DSCF6262s.jpg (501.98 KiB) Viewed 1337 times

This is the interior. To save costs I usually do not prime the interior walls before canvasing. Even without canvasing you can see the print pattern on the foam mirrored on the canvas. This indicates to me that indeed there is a good bonding there. If you look closely you can see a good amount of pink too. I don't remember exactly when I applied the interior canvas, probably over a year ago though.

Without Primer

DSCF6265s.jpg (521.7 KiB) Viewed 1337 times

As you can tell in both pictures there is a bond using both techniques. The issue is how strong a bond. The thing to keep in mind is that foam is not very strong and it does not really matter how strong a glue agent you use it will fail at the glue line. With that said I do feel I have a bit better bond to the canvas using primer first and the TBII to apply the canvas. As you can tell in the pictures TBII bonds real well to the primer and the primer seems to do a bit better bond to the canvas.

I also feel that when applying your primer over the applied canvas it is good to use a roller and work the primer into the canvas. The roller will squish the primer into the weave of the canvas and help some with the bonding of the canvas to the wall as well. Wood canvas canoe makers actually use a brush with real short bristles to work their dope through the weave to the wood underlayment.