Epoxy Warning

I was joining two wing halves yesterday and mixed up a large batch of

30 minute epoxy. The temperature in the garage was about 90 degrees. I had just finished coating the spar that joins the two halves and had inserted it into one wing half and was coating the inside edge of the wing when I noticed the epoxy was already starting to harden. I had just enough time (about a minute to coat the second half and join the wings. The meshed together INSTANTLY! I could not even remove the excess epoxy with alcohol as it had set up so quickly. Word to the wise here. If you are using epoxy in this hot weather, bring it to room temperature in the house first. After I set the wing in place I looked at the epoxy cup and the chemical reaction of the epoxy in combination with the heat of the garage had melted the cup!
Reply to
Ted
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Hi ted, this works both ways, if you mix slow-set Epoxy and use some of it you can stick it in the freezer for a few hours and the cold will stop the reaction dead, then take it out and allow to warm up and it is ready for use. I have used this trick for years with excess Epoxy or I havnt been able to complete a job for some reason, I have used half of the mix and frozen the other half for three or four hours then thawed it out to finish off, Epoxy setting times are calculated at around 76 degeees F so higher air temps speed everything up,

regards, Terry

Reply to
Terence Lynock

Check the age of your epoxy. I have finally learned (the hard way - of course) that old epoxy is the opposite of old CA. It sets up extremely fast where the CA takes a week or more to cure out when it has been aged. What you described sure does sound like old epoxy, or at least like my old epoxy.

YMMV

Jim Branaum AMA 1428

Reply to
Six_O'Clock_High

Isn't that a sick, helpless feeling?? My experience has been that if you are mixing up a big batch of epoxy, it is better to mix it on a large flat surface such as a coffee can lid, than in a cup. Seems the deeper the epoxy, the more heat it generates (or can't dissipate) and the faster it sets up. Just my observations.

John VB

Reply to
JJVB

When epoxy is confined in a small space it will produce heat which will make it cure all the faster. After mixing up your batch of epoxy in a cup or bowl pour it out onto a paper plate to spread it out. This will let the heat "bleed off" without transferring it back to the mixture. As someone else pointed out cooling will slow the reaction and curing time. To make applied epoxy cure faster you can use a heat gun. You do have to be careful though as the epoxy will get a bit runny when the heat is first applied but will then begin curing at an accelerated rate. Another tip for removal of cured epoxy is to heat it up with said heat gun and it will become "pasty" enough to scrape off.

(BTW most of my knowledge of epoxy comes from System 3's Epoxy Book

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Reply to
Mark Daughtry, SR

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