Post Curing

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#1

When post curing an epoxy laminate do you always do so with the part still in the mold?

I’m thinking vacuum infusion or wet lay up/vacuum bagged… popping the part out of the mold, THEN placing it in the oven to post cure This would be done after an initial 24hr room temp cure with part still in the mold and vacuum bag.

This all assumes I can find the right epoxy.

It’s good for me to know this stuff and learn. I understand many parts are V.I.P.'d and it seems some would need a post cure if not being done in an autoclave?

#2

Leave it in the mold & under vacuum for post curing as the heat can distort the part.

Autoclave is not necessary but a large enough oven.

#3

with certain epoxies you can do a post cure with out the part in the mold. Call the epoxy company and ask them if it is self supporting during post cure. And depending on the part you may need to support it up so it doesnt warp. I have used huntsman 8105 in this manner before on many large hign temp molds. However that being said it is best to post cure the part in the mold for many reasons if you can IMO.

#4

Even Autoclaved parts need a post cure IMO

#5

I thought the autoclave doubled as an oven for curing?

Yeah i was a bit concerned about post curing with the part out of the mold. Sure would suck to have it warp.

But some good news, I found a clear epoxy resin that was recomended on this forum that has a tg of 375F. HTR212-386 from ResinServices.

I contacted them and they will sell me a one gallon kit for $90. Pretty darn good price for what the resin is. Room temp cure, shore D 90, tg 375f, not sure about it’s other properties but i am sure it will work for me. These parts are going under the hood of a car, and some are car body parts. From what i hear the sun will heat black carbon fiber up to 200f. on a hot day.

#6

It does act as an oven, but alot of parts need a additional post cure cycle to develop their full strength quickly, or raise the sevice temp.

#7

which is normally done in the clave in the same run. I do heat cure epoxy VARTM runs which include the post cure in the cycle.

#8

Even though it’s room temp cure, this will still need post curing to reach those properties, right?

#9

The way the data sheet reads no post cure is needed and the data sheet offers no post cure temps/times. I believe it is tg 375f with room temp cure.

#10

What?! The autoclave cycle IS the post cure.

#11

might be. When in doubt, call them and ask :slight_smile:
I hate the epoxies that take 30min to heat cure at 200…then 8hr at 300 post cure…oi!

#12

yeah 8 hours is a long wait and burning up extra electricity. I’m afraid of leaving equipment on and unattended.