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Sealing with epoxy--any reason NOT to do it before assembly?

PostPosted: Wed Sep 20, 2006 6:28 pm
by kayakrguy
Folks,

We are going to seal the roof/walls/door exteriors and with thinned epoxy, which I know many on the forum have done. My question is: Is there any reason that cannot be done before putting up walls and roof etc?

Our interior surfaces have all been varnished (3 sanidings, 3coats of spar varnish) It would be a bit easier to epoxy and sand while everything is still flat. Whaddya think?

I WILL be using regular epoxy for roof seam, blemishes etc after the walls and roof are up....

Jim

PostPosted: Wed Sep 20, 2006 6:39 pm
by Steve Frederick
That's it! Do everything you can while it's apart, on the workbench! :thumbsup:

PostPosted: Wed Sep 20, 2006 6:41 pm
by Steve_Cox
Yeah, Epoxy, before, during and after assembly. :thumbsup:

PostPosted: Wed Sep 20, 2006 8:38 pm
by mbader
But white woodworkers glue won't stick to epoxy.
You'll need to use Gorilla Glue or epoxy for glue which is a good thing in my opinion.

PostPosted: Wed Sep 20, 2006 10:03 pm
by EZ
It's pretty easy after it is assembled too. Also epoxy won't stick that well to itself if it has cured unless scuff sanded and then you have only a mechanical bond. As long as you leave bare wood where you are gluing then I'd say OK. However if you assemble the camper and fill the seams and then coat with epoxy it will be totally covered and sealed. Just my opinion.

Ed

PostPosted: Thu Sep 21, 2006 6:22 am
by kayakrguy
Malcomb, Steve, Ed,

Thanks for the heads up re white glue/sanding. I intend two coats with sanding in between.

Ed, scuff coat?--not, say, 220 grit like you would between coats of varnish?
Just rough it up a bit with, say 100-150?

I assume that latex paint will stick to the epoxy? Varnish stick to it?

....brushing and sanding, sanding and brushing--could do it in my sleep by now <g>

Jim

PostPosted: Thu Sep 21, 2006 11:19 am
by EZ
Jim,

100 grit will work fine to scuff sand to paint over the epoxy. Even 60 grit is recommended. I used 100 the last time (on my camper) and it turned out very nice. I was actually trying to let the wood grain show through but for a really smooth finish 2 coats of thinned epoxy with sanding in between works great. We do love the epoxy dust (wear a mask for sure).

Latex paint sticks great to epoxy and my guess is that varnish will too. In fact for exterior use (woody) you must use varnish with some UV protection otherwise the epoxy will break down (and then get ugly and cloudy).

Ed

$$$ vs Practicality...help needed in the alligator pond....

PostPosted: Thu Sep 21, 2006 6:24 pm
by kayakrguy
Folks,

Whoa! I think I probably did not thin the epoxy enough. The result is that I only have the doors and exterior walls epoxied with the first coat and only have a little less than 1/3 of a can of both resin and hardener left. I still have not done the roof panels!

Now, I know that the next coat has to be thinned much more. Will do. Will TRY to stretch it to the roof panels though I know those might be the ones that need the epoxy MOST.

I will order more epoxy if I HAVE to. But if the thinning works and I CAN get the ceiling panels and second coat on what I have already done, I still face patching screw holes, ply faults, wall/roof gaps, etc.

My question is this...for patching purposes is Bondo a good alternative to epoxy? Will it 'stick' if I have already epoxied the walls etc?

Help as always appreciated here in the alligator pond <g>

jim

$$$ vs Practicality...help needed in the alligator pond....

PostPosted: Thu Sep 21, 2006 6:24 pm
by kayakrguy
Folks,

Whoa! I think I probably did not thin the epoxy enough. The result is that I only have the doors and exterior walls epoxied with the first coat and only have a little less than 1/3 of a can of both resin and hardener left. I still have not done the roof panels!

Now, I know that the next coat has to be thinned much more. Will do. Will TRY to stretch it to the roof panels though I know those might be the ones that need the epoxy MOST.

I will order more epoxy if I HAVE to. But if the thinning works and I CAN get the ceiling panels and second coat on what I have already done, I still face patching screw holes, ply faults, wall/roof gaps, etc.

My question is this...for patching purposes is Bondo a good alternative to epoxy? Will it 'stick' if I have already epoxied the walls etc?

Help as always appreciated here in the alligator pond <g>

jim

through thick and thin

PostPosted: Thu Sep 21, 2006 6:47 pm
by jay
thinning the second coat.. with what??? the first coat, thinned, would penetrate into the wood more deeply [in theory]. i don't know the value of thinning the second coat. and is a gallon of epoxy where you want to save money on this job? your labor is worth 10 times more - and NOT free - and the aggravation you save from having a better completed job will surely outweigh 50 - 100 bucks.

being done before, the areas receiving glue could be masked off to prevent epoxy coverage.


and why would white glue be used at all? isn't that casein glue? don't we want aliphatic resin at the very least?

PostPosted: Thu Sep 21, 2006 8:43 pm
by EZ
Jim,

The idea is to thin the epoxy so that it flows and soaks into the wood. I use acetone and it works well. About 20%-30% acetone to already mixed epoxy. You may have to add acetone as you go because it slowly evaporates out of the epoxy.

I did one coat thinned after my camper was assembled as well as both sides of the door and have about 1/3 or more left. You must have used an awful lot because my camper is larger than most (5 1/2 feet wide).

I would think that it might not penetrate as well but it must have dried thicker than more diluted stuff. Maybe I don't understand where you are in your build. Are you going to epoxy a curved roof before you install it? I would think that is a bad idea.

Sand it and see what it looks like. Maybe it will be as smooth as silk. I have never used varnish over epoxy so maybe you aren't supposed to sand; that is uncharted territory for me but others have varnished. A search is always a good idea because this process may have been discussed 20 times before.

Not much help here.......

Ed

PostPosted: Thu Sep 21, 2006 9:34 pm
by kayakrguy
Ed,

Actually, your warning about epoxing (sic) the roof panels was very helpful.
As far as thinning goes, I did what I thought were the approximate ratios that you mention but since this was my first time doing this, I may have been a bit light with the acetone. As far as what is already done, I think it will be fine. I will make the second coat a little 'leaner'--more acetone.

I intend to paint, so my varnish question was strictly hypothetical...just wondering what you can/can't do with epoxy seal once you have put it on.

In any case I will hold off on the roof panels until they on on.

By the way, you DID finally get out of the driveway, right? <g> I hope to do that someday <g>

Jim

PostPosted: Fri Sep 22, 2006 7:04 am
by Arne
I'm thinking of doing more of the finish work before assembly. One reason is stability. If I use cpes on walls before I cut out the doors, there is less chance of warping. I could even paint the walls (inside) before assembly, then touch them up after they are put up, since there will be some scuffing. It would be a lot easier than crawling around inside afterwards.

As mentioned, the areas to be glued should not be done so the glue will stick.

PostPosted: Fri Sep 22, 2006 12:24 pm
by kayakrguy
Arne,

We did our inside walls and ceiling panels--3 sandings, 3 coats of varnish on the bench. I realize there will be some nicks etc, but those are easily touched up. But the vision a Brobdignagian (me) painting in a Lilliputian space (the trailer) did not make sense. I will let everyone know whether the system works satisfactorily or not. But painting stuff while it is flat on sawhorses is a lot easier than what you describe!

Jim

PostPosted: Fri Sep 22, 2006 3:46 pm
by Arne
I had painted my floor in the tear. I spent a lot of time sliding around on an overturned milk crate to save my back while doing walls and ceiling... it is doable, but 10/4 on the doing it on the saw horses. so much simpler..