Re: Plastic sheet and Epoxy experience
How about, if you're only using the plastic once and it's not very
thick, making a pinhole in the plastic to let the air out of the bubbles?
thick, making a pinhole in the plastic to let the air out of the bubbles?
>Jeff wrote:
>snip Using a scrapper only stretches the plastic, then it shrinks back causing small ripples. This is very important, don't over work the plastic! It causes a lot more problems than it'll ever solve.
>
>Secondly, once you get the plastic on, leave it alone, don't try to get more air bubbles out. snip
>
>I will be sheathing the entire outside of my boat with 10 oz cloth. So youOnly in my opinion I guess. Unless you using the Lexan which is very expensive, I think that this plastic from Wal-Mart would not lay smooth on a thick coat of epoxy and cloth and you would end up with wavy results. Even on the thin epoxy/glass stuff you can leave indentations if you pressed down with fingers as you reached across. I can only image that it would be worse with a thicker layer of cloth and epoxy. You probably would not save sanding time in the long run on the thicker epoxy/glass.
>are recommending that this technique probably isn't worth it for that?
This is where the Lexan film would work better because of it's stiffness.
Jeff
[Non-text portions of this message have been removed]
On Mon, 9 Feb 2004 08:53:31 -0700, "Jeff" <boatbuilding@...>
wrote:
I will be sheathing the entire outside of my boat with 10 oz cloth. So you
are recommending that this technique probably isn't worth it for that?
Later,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
wrote:
> If you have heavier cloth, it's probably not worth the effort since you can get it fairly smooth just rolling on epoxy and tipping off with a brush. I'd use it on the real light stuff say under 3 oz. as this stuff is notorious for floating on top of the epoxy and can give you a terrible finish full of air bubbles and ripples if you rush the job. I hate the light stuff but it's easy on epoxy and much cheaper if all you doing is stopping the plywood from checking.Jeff,
I will be sheathing the entire outside of my boat with 10 oz cloth. So you
are recommending that this technique probably isn't worth it for that?
Later,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
I learned a few things using the plastic sheet on epoxy.
Put enough epoxy on to fill the weave or you'll get dry spots under the plastic then roll it on slowly and get as many air bubbles out as possible with a roller, not a squeegee. Using a scrapper only stretches the plastic, then it shrinks back causing small ripples. This is very important, don't over work the plastic! It causes a lot more problems than it'll ever solve.
Secondly, once you get the plastic on, leave it alone, don't try to get more air bubbles out. When the epoxy is setup but before 24 hours, fill the air bubbles with epoxy and filler that's easy to sand like glass beads, or even talc. I used a syringe and had about 100 or so small bubbles in a 4' x 12' area.
Once it's all cured, the sanding is easy because it's so smooth and the air bubbles that where filled stand proud and are easy to sand down. I figured it saved me a couple of hours sanding so far which is by far worth the $12.00.
Now would I do it again? Sure but I'll buy a real good roller and have a second hand to help me to hold it up as I roll. Using the Lexan film would make the job a snap but at a big cost compared to the Wal-Mart plastic.
If you have heavier cloth, it's probably not worth the effort since you can get it fairly smooth just rolling on epoxy and tipping off with a brush. I'd use it on the real light stuff say under 3 oz. as this stuff is notorious for floating on top of the epoxy and can give you a terrible finish full of air bubbles and ripples if you rush the job. I hate the light stuff but it's easy on epoxy and much cheaper if all you doing is stopping the plywood from checking.
One other thing, if I was going to have the wood grain show through and use varnish as the finish coat, I'd stay away from this procedure using the Wal-Mart stuff and spring for the expensive Lexan or anything that won't stretch as you work the air bubbles out.
Jeff
[Non-text portions of this message have been removed]
Put enough epoxy on to fill the weave or you'll get dry spots under the plastic then roll it on slowly and get as many air bubbles out as possible with a roller, not a squeegee. Using a scrapper only stretches the plastic, then it shrinks back causing small ripples. This is very important, don't over work the plastic! It causes a lot more problems than it'll ever solve.
Secondly, once you get the plastic on, leave it alone, don't try to get more air bubbles out. When the epoxy is setup but before 24 hours, fill the air bubbles with epoxy and filler that's easy to sand like glass beads, or even talc. I used a syringe and had about 100 or so small bubbles in a 4' x 12' area.
Once it's all cured, the sanding is easy because it's so smooth and the air bubbles that where filled stand proud and are easy to sand down. I figured it saved me a couple of hours sanding so far which is by far worth the $12.00.
Now would I do it again? Sure but I'll buy a real good roller and have a second hand to help me to hold it up as I roll. Using the Lexan film would make the job a snap but at a big cost compared to the Wal-Mart plastic.
If you have heavier cloth, it's probably not worth the effort since you can get it fairly smooth just rolling on epoxy and tipping off with a brush. I'd use it on the real light stuff say under 3 oz. as this stuff is notorious for floating on top of the epoxy and can give you a terrible finish full of air bubbles and ripples if you rush the job. I hate the light stuff but it's easy on epoxy and much cheaper if all you doing is stopping the plywood from checking.
One other thing, if I was going to have the wood grain show through and use varnish as the finish coat, I'd stay away from this procedure using the Wal-Mart stuff and spring for the expensive Lexan or anything that won't stretch as you work the air bubbles out.
Jeff
[Non-text portions of this message have been removed]