Would like epoxy advice

[flynfrog]

Howdy guys, yet another epoxy question. Was giving a tube a coat of epoxy and epoxy was frozen. In the long run I heated up the epoxy until it turned crystal clear. I thought whats the worse that can happen if I add the hardener? I added the hardener and shortly after like 45 minutes or so this happened.

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The epoxy melted the cup, gelled hard, and of course was smoking away. What is the maxium temperature that I can heat the resin up to so this doesnt happen to me again?

what you have there is an exotherm. can be very dangerous. Room temp epoxies should be used at room temp.

Its not as simple as a max temp total mass of mixed resin also matters. What is happening is the reaction is going at of control and producing to much heat thus feeding the reaction even more. There is no one max temp for epoxies. I have some at work that are solid until about 250F

 

[REK]

what you have there is an exotherm. can be very dangerous. Room temp epoxies should be used at room temp.

Its not as simple as a max temp total mass of mixed resin also matters. What is happening is the reaction is going at of control and producing to much heat thus feeding the reaction even more. There is no one max temp for epoxies. I have some at work that are solid until about 250F

Bummer, thats weird though, because only the epoxy in the cup got like that. The rest of the epoxy that I coated the tube did not harden like that.

 

[rharshberger]

Bummer, thats weird though, because only the epoxy in the cup got like that. The rest of the epoxy that I coated the tube did not harden like that.

The epoxy in the cup was a concentrated mass, the epoxy on the tube was not and it quickly cooled from the temp of the stuff in the cup to room temp, most likely (thats my opinion of course). Its 60 degrees in my shop right now and I have been doing some epoxy work with US Composite 635 w/med hardener, and its pot life is extended a little by the cooler temp, I also mix it in smaller quantities and use wider flatter containers to hold the epoxy after mixing.

 

[JDcluster]

Small confined spaces are not good for mixing epoxy.
A larger surface area is needed for proper mixing / pot life.
I use a 2 qt buck for mixing Aeropoxy and West Systems.

The deeper the epoxy is, the quicker it will cure in the cup.
Try that with 5 min epoxy and it will catch fire due to heat build up.

JD

Bummer, thats weird though, because only the epoxy in the cup got like that. The rest of the epoxy that I coated the tube did not harden like that.

 

[flynfrog]

The larger bucket is nice when degassing too more surface area less depth to pull bubbles out of. If you want to heat your resin id recommend getting it in a larger container or ideally on the part first. PTMW has different resins that are not in the areopoxy line that are higher temp if you want to work with warm stuff. They also have a VARTM resin that I have been playing with that works really well at room temp in heavier fabrics. You might also look at some of the longer pot life tooling resins if you are looking for more work time.

 

[Cyril's Scribe]

The other option is to warm the resin and catalyst separately in whatever containers you feel like throwing away or cleaning up, I like to use plain white vinegar, and then mixing the two together once they have both cooled to room temp.

 

[markkoelsch]

I would say you do not want the resin and hardener at more than typical room temperature-say 75-80 f. Warm them separately.

As others have said, if you are mixing larger batches a shallow and wide basin is the ticket. For small jobs the cup is fine in my experience. I too have had the cup melt a couple times- happens when you have enough mass.