Bondo over Canvas ?

[rustytoolss]

I need to build up a few areas on my TTT. I used XPS foam on my build. Covered the foam with HF canvas/and TBII. Then put 2 coats of TBII as an overcoat But I need to build up some spots.
Will bondo be a problem if applied onto the outer canvas/ or should I use something else. ?

[Pmullen503]

Bondo will melt the foam underneath if not completely sealed. An epoxy based filler would be my choice.

[OP827]

Epoxy or polyester resin based bondo will not adhere to TB2 covered canvas. It can only adhere to water based primers. I don't know what can be used to fair the surface in this case, but you can test mastik that Nodrog used...
http://www.tnttt.com/viewtopic.php?t=69320#p1215601

[Aguyfromohio]

I find Bondo only works well for its intended use - putting thin coats on dents in car fenders.
It cures very fast, which is an advantage to the body shop professional but is a problem for the hobbyist.

Why not epoxy two part lightweight fairing putty? I think it's just epoxy with a filler already in it, so if epoxy won't work neither will these fairing putties.
The picture is West Marine brand here https://www.westmarine.com/buy/pettit-p ... cordNum=17
They also have a version that stays flexible if you are worried about flexing and cracking

[linuxmanxxx]

Great stuff foam sticks to anything and can be sanded and shaped and relatively cheap

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[John61CT]

Pretty hard to control for fine work though.

Agree it sticks to almost everything 8-)

[OP827]

Great stuff is not suitable for body fairing work. It is for filling gaps. It will have big pores inside, it can expand more with time and sands unevenly. Tried it for shaping the foam and ended up coming back for painful repair after it was fibreglassed. I wouldn't recommend using it for trailer surface body shaping. I would not trust it holding to TB2 either. Sorry for a long post.

[OP827]

I need to build up a few areas on my TTT. I used XPS foam on my build. Covered the foam with HF canvas/and TBII. Then put 2 coats of TBII as an overcoat But I need to build up some spots.
Will bondo be a problem if applied onto the outer canvas/ or should I use something else. ?

How big is the problem? If I were you I would either leave it as it is a pmf foamie in the end, OR if you really want to fix it then you could peel the canvas off, rebuild the foam and cover over a fair surface with canvas again. Epoxy based compounds or any other resin will not adhere to TB2 carpenter glue properly. Just my opinion based on my limited experience.

[John61CT]

Yet another data point for sticking to Glidden Gripper over TB2?

[rustytoolss]

Yet another data point for sticking to Glidden Gripper over TB2?

Glad you said that. I did 2 prime over the coats of TBII with Glidden Gripper. Would bondo still be a problem ??

[Tigris99]

bonds also will not deal with the flex of foam, will crack and fall off in short order.

Need to explain what you need to build up and why. Things like damage to foam itself is best fixed before applying canvas.

I cant fi d it at the moment but there is a mixture that is good for filling the weave on canvas builds (something canoe builders have come up with) which may be perfect for your situation. Will take time on Google to find it though.

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[OP827]

bonds also will not deal with the flex of foam, will crack and fall off in short order.

Need to explain what you need to build up and why. Things like damage to foam itself is best fixed before applying canvas.

I cant fi d it at the moment but there is a mixture that is good for filling the weave on canvas builds (something canoe builders have come up with) which may be perfect for your situation. Will take time on Google to find it though.

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Yes, they use ventilation mastic in canoe builds. That is similar/same to the latex based lagging compound mastic I mentioned above from Nodrog build. Bondo can only be applied over bare steel, aluminium, fibreglass, wood - according to manufacturer. It may not stick well to latex primer(GG) or any other latex based paints.

[Tigris99]

I read up on home made mixes that ppl have come up with too but ya, you know exactly what I am talking about. Only option this guy has at this point.

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[John61CT]

DIY filler, mix micro balloons with the GG?

[GPW]

If you have a a flexible surface , you need a flexible Filler … for small stuff and weave filling , I would suggest some Artist Acrylic modeling paste , which is another Latex ( compatible water based ) product , just THICK …  Real thick … Built up in layers like Bondo , but stays more flexible … it sands too … Big gaps , divots , etc. should be filled with more Foam …I’m with Steve , Great stuff , used correctly, works fine … ( try putting on the Great Stuff and keep smoothing it around with your Yellow plastic Bondo spreader … It will stop foaming , then let it sit a while , then sand it and shape it to what you need … We always have some “ Trailer repair in a can “, handy for repairs … It’s not a miracle , takes some skill and PATIENCE , but really does work fine … ( ask me how I know ) …. OK, Half of the Foamstream nose dome is great stuff …

The other alternative is just cutting out the damaged area and replacing it with a fitted piece of new foam , sorta’ like drywall repair ...