mixing epoxy with water - RC Groups
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May 18, 2003, 09:35 PM
Under tension
citabria's Avatar

mixing epoxy with water

I need to make a repair on a foam model tonight to patch a crack that's pretty tough to get to. I don't have any Probond but I do remember hearing that you can mix epoxy with water to lessen its thickness. I searched the group for info on this trick but couldn't find anything. Does anyone do this? What will it do to my hardening time and will it have any effect on the strength of the bond?

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May 18, 2003, 09:46 PM
Registered User
Don't know about water but denatured alcohol works very well. You can also try to heat it up with a heat gun before you put it on the crack.

May 18, 2003, 10:51 PM
Pro Bro #495
fwilly's Avatar
Mine got pretty hot in my truck today and was pretty thin.
May 18, 2003, 11:33 PM
raythomas's Avatar
When I get to the end of my epoxy I will stick each bottle in the microwave for about 8 to 10 seconds. Don't leave it unattended while doing this because the epoxy will get VERY HOT VERY QUICKLY!!! The good thing about this is that it makes it very thin, not like water but close and you can get every last drop of epoxy out of the bottle. The bad thing about doing this is that it causes the epoxy to harden very quickly. The heat speeds up the catalyst process. I would suggest using 20 or 30 minute epoxy for this. 5 min might not be long enough when heated. Ray
P.S. Don't let your wife catch you using the microwave for this! Don't ask me how I know!!
May 18, 2003, 11:36 PM
Registered User
mescal1's Avatar
epoxy cure's by a chemical reaction not evaporation like elmers
or ambroid. i wouldn't try mixing it with water but i have to admit
that i've never tried it either. so, now that i'm curious i'll have to
check it out someday. i also have to admit that i'm surprised
that alcohol works, i'll have to try that out as well. either way,
i'd try it out on scraps before your airplane. the heat gun sounds
like the best way to go for now (i know that works!)
May 18, 2003, 11:39 PM
rpage53's Avatar
I wouldn't put epoxy in an oven that you intend to use for food. Put the epoxy in warm water for a few minutes to achieve the same thing or warm it with your heat gun after mixing.

In this case, I would use odorless CA because you can be sure it will penetrate the crack. Otherwise, put the normal epoxy on the crack and then hit it with the heat gun. Ordinarily, you can easily make it flow into the crack but you also have to worry about not melting the foam.

If you have some laminating epoxy, its much thinner to begin with.

Last edited by rpage53; May 19, 2003 at 12:00 AM.
May 19, 2003, 07:27 AM
Registered User
Flint's Avatar
I use Metholated Spirits (Metho) to thin Epoxy, works great and is very cheap and easy to obtain.

May 19, 2003, 10:46 AM
Stay thirsty my friends.
DR. JOY's Avatar
A good source of methanol is gas line antifreeze. It is what I use to thin epoxy. I would not use Isoprpopyl alcohol as most is cut with water. I have had poor results with it. Heating also works. I myself would probably use foam safe thin CA.
May 19, 2003, 02:16 PM
Striving to Rip the Bring
raptor22's Avatar
yeah, i just use zap-o oderless CA. its better than epoxy, anyway. its lighter, too.

May 20, 2003, 11:07 PM
Mfg of the Marauder & Oculus!
Mr B....'s Avatar
You can make epoxy thinner by preheating at 150 degrees for ten min. before you ad the hardener. After mixing your working time will be less and will get hotter. DO NOT ADD WATER!

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