Quick PSA: overheating epoxy

[Head Monkey]

Just a quick reminder that extra epoxy should not be left in a small mass, but should be spread out to cure slowly. I mixed 50g of my normal QCM mix this afternoon to do a minor repair on a buddy's board. I used only about 5g of the epoxy on the board, and left the extra 45g in the cup. I meant to dump it into a pie plate, but I forgot and just left the cup sitting on the pie plate. Here's some pics of the result, with an undamaged cup for comparison. It released toxic fumes as it ate itself, of course. I was out of the room at the time! I would have preferred to have been there to notice and put a stop to it.

I know this gets discussed here every few years, but I figure a quick reminder never hurts: when epoxy does this, the fumes it releases are toxic, and a large enough mass runs the risk of actually igniting. Stay safe...

[endre]

I burned a black hole in a table once, I mixed epoxy in a polystyrene (foamed) cup. Insulted cups are obviously very bad for mixing epoxy, I got an exothermic reaction in 3 seconds. (this epoxy normally cures in more than 20 hrs at room temp.) It hardened before it started to boil, left no bubles or anything, just a pond of melted polystyrene and a smoking, black hole in the wooden table.

[SHIF]

This is why I only use paper cups, the cheap 9 oz. size from Long's Drugs.

I measure 104 grams of QCM epoxy into several cups prior to a lay-up. The typical resin pump dispenses 26 grams of curing agent per pump stroke. This way I simply dispense curing agent into these mini-batches on demand, thus minimizing waste. I always start with one or two extra cups of epoxy, just in case. Un-mixed epoxy gets transfered back into the can for next time.



-S

[iggyskier]

If you notice at the end of this photo, you will see my reminder to never, ever leave epoxy sitting there. This happened early on and I just left it so I never forgot about it. It sat where I put the other cups of epoxy.

[rockaukum]

What is in the open can in the foreground of said picture?

[iggyskier]

What is in the open can in the foreground of said picture?

ha. funny you mentioned it.

It was some freakish can of acetone that had a top we had to take off with a wrench. Not sure what was wrong with it.

Once I give the base material, edges, and tipspacers a final acetone cleaning, I usually swapped gloves and didn't touch anything but the skis until the were in the press, and sometimes definitely didn't cap the can.

Definitely on the list of things you probably shouldn't do either . Knocking over a gallon of acetone is not something you want to do, but then again, at least acetone cleans up after itself .

[iggyskier]

What is in the open can in the foreground of said picture?

ha. funny you mentioned it.

It was some freakish can of acetone that had a top we had to take off with a wrench. Not sure what was wrong with it.

Once I give the base material, edges, and tipspacers a final acetone cleaning, I usually swapped gloves and didn't touch anything but the skis until the were in the press, and sometimes definitely didn't cap the can.

Definitely on the list of things you probably shouldn't do either . Knocking over a gallon of acetone is not something you want to do, but then again, at least acetone cleans up after itself .

then again, at this point, that can could have even been empty. I think we went through at least 7-8 gallons of acetone throughout the process, Mostly to clean the cassettes as quickly as possible, but it went quick.