An experiment in TB2 and cloth

[Pwfyrcat1]

I bought a piece of foam insulation to experiment with using cloth and TB2.

I cut a swatch of cloth from my "canvas". The canvas in this case was from a hospital blanket. I wet the material and spread it across the foam. I used a watery mix of TB2, and cannot tell you the ratio of glue to water.

l let it set and dry and found this afternoon that I did not use enough glue in the mix the first time. I was able to pull the material away from the foam.

I went over it again, this time I just squeezing the TB2 directly onto the surface and spread it with a brush. Letting it dry.

I wanted to see if the material I've chosen is adequate sock material.

[ghcoe]

I used a 50/50 mix when I did my canvasing. I think you will find the bond will not be real strong even with full strength glue. Some people perforate the foam to encourage a better bond. The problem is the foam is just not a great surface for glue to bond to, it usually still pulls off easily because the foam will fail at the glue line. A lot of the bond comes from the shrinking of the canvas or fabric over the surface creating a tight drum like pull to the edges. That is why you want to overlap the edges so it can pull tight across the surface rather than shrinking away from the edges. If that makes sense. With the combination of a light bond to the surface from the glue and the tight drum like effect across the surface it really makes for a tight durable surface. For it to pull away from the surface I would suspect you would have to push from the inside of the wall out and something bad has happened at that time.

[Pwfyrcat1]

thx. I was curious about what is a good ratio.

[pchast]

Also the foam has a release agent on it. It improves
things a little to do a quick sand of the surface before
gluing.

Just scuff it up lightly with 60 to 80 grit on a pad sander.
Alternately you could use a wallpaper scorer...

[Pwfyrcat1]

This morning I tried out some enamel spray paint to see how it would cover the fabric. Not as well as I would like. Definitely appears to be a roll on application. Also, I don't know if you can see it in the pictures, the foam is a bit lumpy underneath. I'm thinking it's the paint (enamel) that caused the degradation.

[ghcoe]

If it is the hospital blanket material that I am thinking of I think it is going to be to stretchy for a good skin. Canvas works beautifully because of is weave and that it shrinks. I know some people prewash their canvas to take some of the shrinking out of it. I found that the shrinking once applied really helps in removing a lot of the wrinkles and again makes a nice tight skin. Here is a picture of the canvas being applied to the hatch. You can see that I just unfolded the canvas from the package and started to apply to the hatch. No prewashing, no ironing needed, 50/50 mix.

Shrinking

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I do use a roller to press the canvas down and work out the wrinkles. You can read in my build how I apply the canvas, I have a couple of tutorials of how I do it in there.

Here is a shot of the same hatch installed and painted at a good angle to see how well the canvas laid down.

Hatch painted

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I used Harbor Freight drop cloth canvas for my canvas supplier. The large package http://www.harborfreight.com/9-ft-x-12- ... 69308.html 9'x12' has a seam down the middle, but is enough to cover two 5'+ wide by 9' long pieces. In my case just enough to cover the 8'2' side with shrinkage. It did shrink the most on the long length. The price is good and you can use their 20% off coupon to get it at a better price. Not sure of the weight but I would guess in the 10 to 12oz range. Good luck

[Pwfyrcat1]

I took an opportunity to continue on with TB2 and cloth.


I scored the surface of the foam with a piece of 60 grit sandpaper. Serious looking road rash. I brushed straight TB2 on the surface and spread the fabric across. I then brushed the cloth into the glue on the surface. As I was having a difficult time spreading out the glue, I lightly diluted the TB2 to make it spread easier.


I am at work and am using what is on hand. But I wanted to see how the paint covered the fabric once dried. I am loving the color. So Kansas! Maybe this'll become the sunflower build. Not to worry not using the paint pictured.

Letting it dry. The brush I used was shedding bristles like crazy.

[Pwfyrcat1]

Happy with the way it turned out. Added a scond coat of paint. Still have a few places that did not cover well. Attribute that to the paint used. The glue is holding very snug.

Glad I tested this out

[KCStudly]

Something to be aware of (that may not have been an issue on your smaller test sample) is that some people have had issues with the canvas bubbling up when top coating before the bottom adhesive layer has fully dried. On a smaller sample you may have gotten away with it, but for covering a large area it is recommended to use plenty of glue for the initial stick; let that fully dry; and then top coat.

I'm sure others with more hands on experience can elaborate.

[daveesl77]

My front and rear areas are covered with PMF. I used a 25% dilution on the TB2, perfed the foam with a board I made that kind of looked like a cricket bat with a gillion little brads driven into it with my air gun. Just beat the snot out of the foam. Rolled on a layer of the TB2, had prewashed the canvas, which I bought at Wally World for less than $6 per yard in 72" width. Laid on the canvas, rolled out with a large foam roller and added another layer of TB2 over the canvas, while everything was still damp. Waited 2 or 3 days to allow for full drying. It bonded magnificiently. On edges, I had cut the canvas to overlap the wood sides by about 1" and but adhered the canvas initially to the wood with pl300, then coated with TB2. Finally painted using a good exterior latex paint. Did 3 initial coats. Absolutely no bubbles or lifts, looks like it was sprayed on. IN the next few weeks we will be putting on the final "color" coat of paint over the entire front/top/rear. Our top is EPDM and after seeing how well the PMF worked, I regret spending the money doing EPDM for the roof area.

dave

[KCStudly]

Dave, refresh my memory for me please; is your canvas over wood or directly over foam? The absorption rate will differ if gluing directly to foam.

Edit: Oops! Says right there that you perforated your foam. Doh.