I'm having trouble with my epoxy kicking in only 5 mins after mixing.I mean the cup get's very hot to the touch.I only mix it for 10 secs or so.Could I be mixing it to much?Any ideas would help.Thanks,Mike

What brand epoxy?

Here's a dumb question. Did you get the 5 minute hardener mixed up with the 30 minute epoxy? I'll bet you wonder why I ask!!?? HMMMM!

Kwik Bond from hobby people

No, This is the second time this happen so i double checked and I used the 30 min

Epoxy is fun stuff! I had this happening to. Thought mine was incorectly labeled as Tower\Greatplanes had a recall but then I mixed up some more and it seemed about 30. On some epoxies I think the 30 is the time that is setup by. Not the working time. I got some epoxy at home depot and it said 25-30 on it. It was starting to setup in half that time. I think ambient temperature has an effect on it. You need to mix it more than 10 seconds. It needs to be thorough. Could be you're getting more hardener than resin to. Since you know how that epox sets up you can plan when you use it. Try a different brand and it will probably set up different.

You're mixing too much epoxy in too small a container. The epoxy curing process is exothermic, which means it gives off heat. If you mix too much in one batch and don't allow the heat to dissipate, it could go into a runaway situation where more heat = faster cure and faster cure = more heat.

BE VERY CAUTIOUS! Burning epoxy fumes are extremely toxic. Mix epoxy in smaller batches and/or in a wider cup in a well ventilated area. If it does start to get too hot, hold your breath and take it outside QUICK. Your lungs and brain cells will thank you for it.

Hi,
I'm dismayed, but not surprised, that this is still happening.

About a year ago, I had 4 minute set up time on my epoxy; either 30 min or 15 minute label, don't recall which. I believe it was thirty. Hobby stores all buy from two or three sources and put their own name on the bottles. Mine was made by Bob Smith; he was very courteous, and kindly offered to replace my screwed up new wing; but I managed to fix it. His explanation for the fast set up was that, about three years prior, he had recalled a bad batch in which the hardener had not been mixed before bottling. Properly mixed hardener is slightly yellowish; unmixed hardener is clear and won't work right.

He said mine was probably old stock that missed the recall. I do know that my local hobby shop only orders small quantities and doesn't have any old stock.

Complain to both your dealer and the bottler. Even if no harm was done, they should be notified to not sell their remaining stock and to refund your money. If damage was done, obtain replacement or a little compensation. I accepted some replacement epoxy and CA.
Good luck.
Bob

Hi Volfy
You're correct that mixing large quantities will speed up curing; however, in view of the extreme cure rate, along with my own experience which was duplicated exactly by the hobby store owner mixing a small quantity, combined with Bob Smith's explanation of prior bad batch possibility, the problem seems not to be quantity nor container here.
I suppose the only solution is to test a bit before using any epoxy.
Bob

Tower hobbies has recalled 30min epoxy b/c its really 6min! check "the clubhouse"(i think) for more info

Chris

And what does this have to do with ARFs?

If the 30min epoxy just sets up in 5mins without getting hot, then I would say it's mislabeled or formulated wrong. However, if it gets hot to the touch, then you're definitely mixing too large a batch in too small a container. Either that, or the formulation is seriously messed up.

Having said that, my Tower 30min epoxy does gell much faster than 30min - more like 15min. Annoying, but not bad enough to be unusable.

Thanks for all your input.I did try a small batch and it did work a lot better.Thanks,Mike

I once mixed such a large batch of epoxy that the clock in my shop started running backwards.