ORIGINAL: darock
Go ahead, thin it with water and see what happens. I suspect you won't be chuckling anymore
I should have made it more obvious........ chuckle
The drug store isopropyl alcohol is only 70% isopropyl alcohol. What do you guess you're thinning with when you use it? So you're actually already thinning with water. And therein lies the answer..........
chuckle.....
Guess what, 70% is NOT the only grade of drug store isopropyl. chuckle...
I said that you can thin with water, and darn if you can't. You could thin with mud if you wanted to. Or motor oil. chuckle.... (but I wouldn't if I were you) If you're smart enough, it'll be obvious to you whether or not you should thin with water or mud and whether or not it'll make the epoxy stronger. But to save misunderstanding, don't thin with water or things that have water in them unless the strength of your epoxy isn't really important.
Sure, one can thin it with whatever they please. However, if they want it to cure, it's best to stick to things that have been proven to work.
None of us are setup to do a quality test of the resulting strength of our epoxy, nor do any of us do any kind of test other than maybe a crash test later. Sure, some look at and touch the epoxy later on after application. But painting epoxy on a firewall isn't exactly an application that requires all the strength of the epoxy. And everybody forgets that whatever is trapped by the cured epoxy is adding weight.
Do yourself a favor and do a little test. Mix up a batch of epoxy in a little cup. Weigh it. Thin it with whatever you wish. Weigh it right away. Let it cure. Weigh it again.
Do another little test. Mix up some epoxy. Spread some of it on a balsa sheet. Now thin the rest with whatever you wish. Spread it on the other end of that balsa sheet. Let them cure. Now break the sheet where the two epoxy spreads are.
It's amazing how simple and easy some questions are answered for ourselves.
Even easier than reinventing the wheel, go do some searches online. West Systems IS equipped to do the required testing. They've concluded that diluting epoxy weakens it and can cause other issues. Their tests show that even a small amount such as 5% produces measureable changes. Even though the application being discussed does not require significant strength, it's still important to meantion so someone who doesn't know any better does not decide to dilute epoxy for some other application, such as wing or stab joints. Think this won't happen? Think again.
This is a beginner's forum. It's important to provide accurate information because people come here to learn. Belittling people who provide this information, making light of it, or making off the wall suggestions does nobody any good.
Edit: for those interested in learning more about this subject, I've found the following article to be helpful:
http://www.westsystem.com/ewmag/14/ThinningEpoxy.html