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Dec 16, 2007, 11:06 PM
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lake flyer's Avatar

epoxy thinner

Is there a way to thin epoxy to keep the weight down when covering foam with glass ?
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Dec 16, 2007, 11:20 PM
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Isopropyl rubbing alcohol, get the 91% stuff and not the 80%, can thin it down as much as you like. The other approach is a heat gun and a toilet paper roll--use the heat gun to make the epoxy flow like water and then roll the toilet paper roll over it to soak up excess, peel off the soaked TP, and do the next section. If you use TP, be sure to roll it in the direction that does not unwind the paper....Pete M

PS--unless you really want to use epoxy, you could use water based polyurethane instead to hold the fiberglass down...
Dec 16, 2007, 11:28 PM
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portablevcb's Avatar
I like to use denatured alcohol when thinning epoxy. I'll still use paper towels to soak up the excess. But, I haven't used it enough to be good at it either.

Dec 16, 2007, 11:45 PM
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lake flyer's Avatar
I will give the alcohol a try .

Wouldn't heating it also cause it to cure too rapidly ?
Dec 17, 2007, 06:06 AM
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The toilet paper and denatured alcohol has worked the best for me . Go easy on the solvent , too much can change the properties of the epoxy .

Mike 1484
Dec 17, 2007, 07:20 PM
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I have used with great success the Dan Parsons
0.6 oz cloth and his method of glassing which can be found here; http://www.geocities.com/condorsrc/t.../fibrglas.html

I use Pacer Z-Poxy (PT-40) instead of the epoxy that Mr. Parsons uses. Using his procedure is the easiest I have found for glassing because the epoxy is thinned so much that the resin can be brushed on and allowed to cure. There is no blotting with toilet paper or scraping with a playing card or whatever. Just paint the resin on and let it cure. The 0.6 oz glass cloth and the thinned resin lays into concave corners and around compound corners with ease.

I also did not bother with the scale weighing of the two epoxy parts, just mixed it 1-1-2 per his recommendation and tried it on several test pieces of scrap balsa, liked the results and used his method to glass the actual airplane, a 1/6 scale GP Cessna 182 Gold Edition. Be sure and apply a second coat of thinned e-poxy, per his recommendations, because the first coat is so thin and you want to sand it you will be sanding the glass fibers right quick, to quick.

I have both 91% isopropyl alcohol and methanol in the shop and don't remember which I used for the thinner, the 91% alcohol I think. Mr. Parsons says either will work. You could make a small test batch using your choice of thinner and go from there.

If you have tried the classical method of glassing, playing card scraping or toilet paper blotting or wiping excess epoxy off with bunched paper towels, and hated it, this method will change your glassing life forever.

Dec 17, 2007, 08:28 PM
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lake flyer's Avatar
Thanks again for all the help. I will be thinning with isopropyl alcohol .