05-27-2003, 11:53 AM
I followed your thread about applying the PETG film over epoxy. Very nice. I would like to try this shortly and have a couple of questions.
1. Although it is softer, would Lexan work instead of the Polyester? Will the epoxy release from it easily?
2. On your weave-filling coats of epoxy, did you thicken the epoxy with something? If so, what?
05-27-2003, 02:34 PM
Hey Dave, (and others who love glass-flat finishes without sanding, filling, sanding, filling . . . )
The polyester film is the best choice because of cost and its ability to not bond to the epoxy. Lexan film will cost three times that of PETG or Mylar. I have not tried polycarbonate (Lexan) film and I suspect that it will release fine, after thorough cure of the epoxy. If you try to peel the film off too early, even the PE will stick too much and evidence itself in shearing the glass fibers, causing a "whiting" of the fibers.
Lexan and some PE film come with a thin film release liner, or cling mask film that can be left on the film, insuring that the main thick film will peel off fine - even allowing re-use of the film again. I peeled off the release liner immediately as I layed it in the wet as shown below:
I did not thicken the epoxy at all, and this is how I did it:
I rolled on a thin sealer of West 105/206, (207 preferably, but I was frugal) then I layed in the 4 oz cloth, then mixed up 105/207 and poured down the side while I rolled it in thick, but not dripping off too much. I used a 6" wide flat rubber speedball roller - easy to clean or you can apply masking tape to the surface and not clean it - I just sand it down to the tape after cure with my RO sander as it spins. I get multiple reuses without the mess of cleaning it off.
Then I lay in the film (.015 to .040 but .030 is best) and roll out the bubbles - soothing work.
This will only work on flat curves, not compound curves, unless you go with thinner, more stretchy film, and even then you risk the film creeping off in an ugly spreading bubble. Don't bridge over buildups of multiple layers of glass tape at the chines unless you use a lot of epoxy to fill the valley. Minimal valleys are fine, and this film method is great for feathering epoxy from thick to thin.
If you can't get the bubbles all out, you can peel the film off, add more epoxy, and resume rolling out the bubbles - I had to do this a little when I spent too much time rolling the aft end and found that the 105/205 (fast hardener-not smart) sealer was setting up too soon near the bow to roll out. You cannot tell at all that it is thicker here. Hopefully it won't blush there in time. WEST technical help said that I would be fine with the 207 over top, coupled with varnish and the fact that this is a somewhat shaded part of the boat - not like a foredeck.
I suspect that if more people saw this, this film procedure would become standard practice. It actually is standard practice to lay in a release fabric that is pulled off after cure, leaving a rough surface for subsequent coats of epoxy, but this film is superior to that in that it "pre-fairs" the surface by the thick film's flat memory, leaving no wrinkles or waves.
05-27-2003, 02:53 PM
John, thanks for the reply. I'm not sure where I might find the film locally. Might be cheaper to go with the lexan than to drive up to the Twin Cities to get film. I've got some small areas to do and thought I'd give it a shot.
05-27-2003, 03:15 PM
I've had good results using heavyweight plastic constuction tarp material. Haven't measured it but it's thick enough to be translucent and when it hits the epoxy the bubbles are easy to see. I assumed it was vinyl but may be poly. I comes folded on a roll so has some creases but with the heat I'm dealing with I plan to spread it in the sun before getting a warm body to help set it in place on the deck this weekend. How are you putting pictures in your posts?
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