Bondo over Epoxy?

[Mark42]

I have been messing around with making fairing compound using epoxy mixed with the glass micro spheres (Cabosil). I am not too thrilled. Fist, it is still made from EPOXY so its still hard to sand. Second, it tends to sag when it kicks off, so I have to be sure the surface is level. Third, the stuff is really hard to mix, and I spend so much time mixing, that the working time of the epoxy is reduced from about 20 minutes to 10. I'm mixing the epoxy to spheres 1:4 by volume.

So, I'm wondering why I shouldn't just use regular body filler as a fairing compound. Its cheap, easy to sand, sticks to pretty much anything.

I know that polyester resin does not stick to epoxy well when doing glass lamination. But if the epoxy is roughed up, and not a glossy surface, OR primed, why shouldn't bondo work just fine?

 

[oops!]

Re: Bondo over Epoxy?

did you try a more cab/bubbles to resin ratio?
and have u used the mixer trick? (got one from the local second hand shop)
it mixed the stuff really well and fast.....i just pre mixed before i added the cat.....when the cat was in....it was allready smooth and just needed a minit to mix the hardner.

btw.....as far as the bondo thing
whacha using it on mark?....bondo absorbs water.....

in the fiberglass repair manual...it says bondo is "ok".....but in real life coors said he had real problems with it...(i think it was coors)

thats the big problem with fairing epoxy....the words easy sanding and epoxy dont go well togeather....

thats one of the reasons i didnt use epoxy on my proj.....i was repeatedly warned away from it...

however.....ill be meeting with my local glass rep today....ill see if there isnt a product on the market for you....

cheers
oops

 

[Mark42]

Re: Bondo over Epoxy?

OOPs, this will be used on the hard top. It will be above the water line, it will be painted with a top side paint, and it is a trailered boat so it won't be in the water more than a few days at a time. I don't see that being any different than bondo on a car that sits outside uncovered 24/7. The big difference between a car and the hard top is the epoxy/glass factor.

The question is more of adhesion than water absorption.

Maybe Bond-o will kick in this two cents?

 

[oops!]

Re: Bondo over Epoxy?

im sorry ....im really tired......

ill ask about the adheasion....but i dont see any big problems...

bond-o, while being a super guru.....the name doesnt stand for auto body.

 

[Mark42]

Re: Bondo over Epoxy?

No problem. Hard to keep track of all the projects going on here.

I know Bondo has done some large projects. Don't know how/what his handle came from. I just figured from the body filler.

BTW, I am an artist when it comes to body filler. I can sculpt the statue of David in under 1/2 hour, given fast enough cure time.... LOL!

Oh yeah, if Coors can add his 2 cents, that would be great too!

 

[drewmitch44]

Re: Bondo over Epoxy?

im sorry ....im really tired......

ill ask about the adheasion....but i dont see any big problems...

bond-o, while being a super guru.....the name doesnt stand for auto body.

Ask who? This is what mark is asking.

 

[Mark42]

Re: Bondo over Epoxy?

Hey oops! Did you get to ask you glass supplier about bondo over epoxy? And what else does your book say about it?

 

[ondarvr]

Re: Bondo over Epoxy?

Auto body fillers are just polyester resin, so they don't stick all that well to epoxy.

 

[Mark42]

Re: Bondo over Epoxy?

Auto body fillers are just polyester resin, so they don't stick all that well to epoxy.

Right, actually body filler is mostly poly resin and talc powder. I know poly is not good to apply over epoxy to laminate glass where it will get stress and eventually separate, but bondo is just a skim coat that does not take stress like laminated glass does. So I have read of people using it, some products say that they are compatable, but I wanted to get some input from members who have actually used bondo as fairing over epoxy and what (if any) problems thay encountered.

BTW, I was working with the glass spheres again, and its not as hard to sand as I first thought.

 

[ondarvr]

Re: Bondo over Epoxy?

Some people do use it (polyesters) over epoxy including bondo and it does sort of stick, but it's like hanging a picture on the wall, it'll stay in place until it gets stressed. This can be from heat, water, sun, flexing, mounting a bracket, pounding in rough water, or almost anything, it doesn't need to be a structural part of the hull to get stressed.

I've tried to get a good bond with polyester to epoxy and was never able to get a bond that I was comfortable with, I was always able separate the two far easier than needed for marine (or any) use.

 

[Bondo]

Re: Bondo over Epoxy?

I know Bondo has done some large projects. Don't know how/what his handle came from. I just figured from the body filler.

Ayuh,....

My last name is Bond,... I'm been Bondo to my close friends since before high school....

I've always Hated doing body work,....Although I've done Plenty of it,...
I like Instant results, Turning wrenches you see the results in minutes,...
Sanding usually takes Hours to see results....

Back to Topic,....
Sanding epoxy is never Easy,.. But with power sanders,+ reasonally aggressive paper, It can be done...
I mix Alot of spheres,+ just enough cabosil to hold on less than horizonal surfaces....

 

[oops!]

Re: Bondo over Epoxy?

good to see ya down here bond-o

and mark.....my rep said the same thing as ondarvr.....(go figure.....rvr trained him )

as far as an artist.....wanna scuplt my dash board?

 

[Bondo]

Re: Bondo over Epoxy?

good to see ya down here bond-o

Ayuh,....

Gotta stop on down,+ catch the latest on the Hull Extention,.....

Just don't have much time to post, after going thru the I/O forum......