I need to slightly thin some 30 minute epoxy to make glassing a wing center section easier. I know that the high water content of isopropyl tends to weaken the epoxy, so which would be best? Denatured ( ethyl with methanol added ) or straight methanol?
On Tue, 28 Jun 2005 10:16:49 -0400, "Mark D. Fain" wrote in :
If you're just fuelproofing or otherwise "painting" the epoxy on, I'll bet you couldn't tell the difference between these two.
I'd use whatever you have most of on your shelf.
If you're trying to get epoxy to flow a bit and want to retain much of its strength, you can heat it. It doesn't take much. It will flow like water, then set up very, very quickly. Check for drips and clean them up quickly--you've only got a small window of opportunity to do so.
I don't use alcohol at all, spread the stuff on, use a heat gun to GENTLY warm the epoxy up a LITTLE, and it will flow and soak through the fiberglass into the wood VERY well use one of those fake credit cards you keep getting in the mail as a squeegee to force the epoxy through the cloth and to get any air bubbles out, once you can clearly see the wood grain through the fiberglass, the glass is fully saturated, and the epoxy is down to the wood. then use a roll of TP or paper towels to mop off the excess epoxy
you may want to go back later and fill the mesh with something later, but leaving gobs of excess epoxy on the surface adds a LOT of weight and contributes very little if anything to the strength.
You may want to hunt around for some epoxy resin that's meant for layup. Glues are intentionally thickened; a resin will be formulated to do exactly what you want.
Please excuse a newbie question, but I have seen this before and not understood it very well. Do you mean using the whole roll of TP/towels like a paint roller? Is there some way to use the absorbent without it sticking to the epoxy & mixing with it? Is this done in addition to the credit card squeegee?
Don't add alcohol to epoxy. It screws it up. I mean, you use epoxy because it is supposed to be strong. If you don't care how strong it is, use water based polyurethane paint. It works well as a fiberglass binder too.
But, as Marty suggested, to thin epoxy, the best thing to do is to use a slow curing epoxy and then heat up both tubes in warm tap water. That will thin it to good brushing consistency and will not significantly weaken its strength. It does speed up the curing time, so keep an eye on it.
That is exactly what I do, use it like a paint roller. move pretty fast, and keep stripping off the outside layer.
It doesn't take NEARLY as much paper as you would think, particularly if you use a "credit card" or old playing card or something to squeegee off most the excess before you mop up the drips.
the epoxy will tend to act almost like heavy oil or thin grease, and the TP or paper towel will pretty much skate over the top without sticking PROVIDED that you work fairly quickly, and don't let the epoxy get tacky before you start cleaning up.
Another good thing to do is to heat the parts to be glued with the old heat gun, rather than the epoxy itself- this does not shorten the pot life of the mixed epoxy, and really makes it flow into every crack and soak into the wood as soon as you apply it. - I'm here to help - Paul
Go to the drug store and get some 99% alcohol. Last I bought was about $3 per pint. I have been using this for years with no problems. I also thin Epoxy finishing resin with it for glassing / reinforcing Quickie
500 pylon racer wings .Powered with Nelson engines they go over 150 mph. Holds okay on these.
Laquer thinner works well. Some contain a small amount of alcohol, but not enough to attract much water. But this will weaken the epoxy. I only use it for fuel proofing.
Lyman, WHERE do you find Epoxy thinner? I've never seen anything labeled as such. I use alcohol which is listed as the thinner in a lot of places. It works great.
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