Pushing the temperature envelope

[jbo_c]

Next week highs will be 60-65 and I have only slow hardener. I can keep the epoxy in the 70s prior to mixing, but I’m working outside. Other than not quite as easy to wet out the glass, should I be Ok to keep working?

I’m saying I’ll end up laying glass around the high temp, so the overnight “cure” temps will be dropping to the 40s. I understand from reading that cure will continue again once temps rise the next day.

Am I pushing too far or OK to keep going? I’ll have to stop work soon either way.

I could get faster epoxy by then, yes, but I don’t really need anymore.

Jbo

[Reid]

Jbo,

You can keep going with the slow hardener, however, it will take longer to cure. Try and do the initial layup when temps are at their height. If available, use other means of raising the temp after layup, heat lamps, space heater, etc... Be careful not to blow/apply direct heat on the lamination (heat gun or heat lamps too close). This can cause a lot of heat related air bubbles. You simply want to increase the ambient temperature around the lamination. If temps stay below 60 then it may take a couple of days to fully cure. You could also use a warm bath to raise the initial temp of the resin and hardener. Be careful not to raise the temps too much as this can have a negative effect on your pot life and work time.

Good luck,
Reid

[fallguy1000]

Overnight temps are key. And watch for blush with a finger test for greasiness.

[TomW1]

Jbo hang some plastic around the outside of the boat and get 4 space heaters and place them at the 4 corners of the boat under it. This will keep the bottom warm and transfer the heat to where you are working. The fans should be about 3ft from the ends of the boat and the ones at the ends slightly angled towards the other side, so you get a circular flow going. At the end of the day cover the top of the boat so heat does not escape.

Hope this helps.

Tom

[jbo_c]

Heat isn’t (really) an option. I’m building in an open pole barn about 100 yards from a house and electricity.

Pretty soon I’ll be done until spring regardless.

But if I can get the inside glassed, I can put together all the frames/bulkheads in my shop over the winter. (Boat won’t fit.). That should really speed up early spring progress.

Jbo

[OrangeQuest]

I had to do some epoxy work in the same conditions. All I had was the slow hardener I bought for summer work. I tried to avoid doing anything when the air would drop below 55 deg or so at night but I may have still done it anyway. It extended my working time for one thing, but the epoxy still cured correctly, just took longer. I would apply epoxy in the morning while the day was still heating up. The epoxy had the warmest part of the day to cure and most days, it would pass the fingernail test by the next morning. If I was using clamps to hold something together, it stayed clamped for 48 hours just to be sure it cured enough to stay together. But it worked great for glass work. I kept my resin and hardener indoors where it could stay warm and still mixable.

If you have doubts then just do a few small areas to test your results. Otherwise, wait for warmer weather.