epoxy -- freezing during curing OK?

[Charles Neuman]

Is it OK if epoxy freezes some time during its curing?

I am working on ways to heat my shop space. A 1500 W electric heater helps, but doesn't quite do it. I'll need more muscle, probably propane. Since I wouldn't want to leave a propane heater unattended all night, I would have a situation where epoxy is curing during the day at room temperature, then freezing at night. If I use a fast cure epoxy, most of the curing could take place during the day, but it would still experience freezing at night. I'm curious what problems this would cause. My guess is that the epoxy would eventually cure fine. However, the wood could expand and contract with the temperature changes, and that could be a problem, depending on what I am epoxying. Any ideas or suggestions?

[ 12-06-2005, 09:59 AM: Message edited by: Charles Neuman ]

[Lewisboats]

cover the affected areas with polytarp and stick an electric heater under the 'tent', don't try to heat the whole garage. Leave a little air gap above the top of the panels/structure so the air can get above your work.

Steve

[Al Owen]

Electric blankets work well , once the epoxy starts to set. They don't use a great deal of power, and are controllable as to temperature.

[Dan McCosh]

Answer to the first question is no, lower temperatures do affect the curing and strength of the epoxy. The polymer chains do not reach their normal length when cured at low temperatures. High temperature curing, including using ovens, is commonplace in making high-stength composite laminates. If the purpose is only a coating, you can probably get by, however.

[ron ll]

I have a similar situation except on the boat, not in a shop. I am reluctant to leave any kind of a heater unattended on the boat, except that the engine has a block heater that mitigates the extremes a bit. I will be using West 205 hardener which they say is good to 40F or below. It probably will be in the mid 40s during the day, but could drop into the mid 30s overnight. Am I asking for trouble? Or do I have to postpone until spring?

[Tom Robb]

"When all else fails, read the directions"
A motto I live by. :rolleyes:
One could, in a pinch, call/email the manufacturer and ask those who ought to know....

[Norman Bernstein]

I have a similar situation except on the boat, not in a shop. I am reluctant to leave any kind of a heater unattended on the boat, except that the engine has a block heater that mitigates the extremes a bit. I will be using West 205 hardener which they say is good to 40F or below. It probably will be in the mid 40s during the day, but could drop into the mid 30s overnight. Am I asking for trouble? Or do I have to postpone until spring? I use West System epoxy all the time in an unheated garage. I do use a kerosene heater while I'm working in there... but after I'm done for the evening, it cools off rapidly to ambient temps. I use simple heat lamps for spot heating epoxied joints where possible... and if they're well positioned and not near anything combustible, I'll leave them on while I'm not working in the garage.

In my experience, West System epoxy will always cure, even if the joint has gone cold, as long as it spends sufficient time at sufficient temperature, at SOME point... even days later.

There is one caution I'd want to state, however: if you're using epoxy to laminate something on a form, and it's left to cure in the cold, there can be significant cold flow EVEN IF IT SEEMS THAT THE EPOXY HAS FINISHED CURING! I did some laminated curved carlins for my catboat project, left them to cure in the cold, and they seemed fully cured, judging by feeling the squeeze-out... but when they were released from the mold, there was significant spring-back.

I re-made them, and this time, brought them into the warm house to cure. When I finally released them from the clamps, there was no perceptible spring-back.

[seayou77]

There is a story about a twelve meter under construction when a security guard turned the heater off at nite while frames were curing. The boat raced but was scrapped after the series cause the frames delaminated. Epoxy has progressed but be careful.

[George Roberts]

I don't think that epoxy will freeze at normal winter temperatures.

As others have said the cure time might be rather long and the state of cure might not be as obvious as desired.

[wyndham]

I do the same thing as IRONMULE I use Freench Fry lights from Home Deopt. Cheap, safe, easy to use. Buy three or four simple porcelain single bulb sockets like you'd use on a closet ceilig, moun them to a piece of plywood and set them on the shop floor under the work. My lay up and clamping table is usually a sheet of ply on top of a pair of horses. With four lights under neath whatevr is on the table stays warm enough to cure.

[stephen e morris]

I use MAS epoxy.cold does not affect it,just lengthens cure time.You can check out there website or give them a call.the stuff doesn't blush either -I have used it for years-cold was never a concern.

[Charles Neuman]

Thanks for the suggestions. I just got an infrared light bulb with a clip-on fixture. Make sure to get one that handles the power of the bulb. For a 250W bulb, I had to get one with a porcelain fixture.

I think this will do the trick. Propane by day, and infrared radiation by night.

I found an interesting safety product. It's a smoke detector that links up with another smoke detector of the same type. If one goes off, the other goes off. It's wireless, of course. So I could have one in the shop and one in the bedroom. They are expensive (about $80 for two), but it would provide some peace of mind.

Charles

[Aramas]

'Epoxy' isn't a single, homogenous thing. It has lots of components that have different phase change(freezing/gassing) temperatures. Some components will freeze before others, and may cause those components to clump together in crystals or dendrites, cutting them off from the curing process.

So freezing is bad, hmm-kay?

[Y Bar Ranch]

I built an Arctic Tern stitch and glue kayak in the absolute dead of winter, in the garage, in central PA. Many times the temps were in the low 20s in my garage. Obviously, I wanted to get it in the water.

Used System 3. No heat lamps or other external heating. While mixing, the epoxy would warm a bit and then I'd apply it. Sometimes it took days for the epoxy to cure. One bottle of resin crystallized and had to be warmed to undo it. But with patience and cold fingers I was able to do everything, including wetting out all the fibreglass tapes. I waited until it warmed a bit before doing the single layer of fibreglass over the upper hull.

I've had it out in major ocean surf, including pitch-poling in a wave I should have let go by. Structural integrity is still A-OK.

But I waited until it warmed up to do the second one. If I did it again, I'd use heat lamps, even if only just to speed things up.

[BrianY]

built an Arctic Tern stitch and glue kayak in the absolute dead of winter, When else should one build an "Arctic Tern" ? :D

[ron ll]

I applied some epoxy last night in my shop at about 40 degrees and this morning it had set up fine. I used West with 205 hardener. One very pleasant surprise was that there was virtually NO odor or fumes. The can says "odor free" but I didn't believe them. Totally different than Smiths penetrating epoxy which actually elicited complaints from our neighbors over the smell.

[Andrew]

You can judge the cure of your epoxy by the state of the left overs in the mix pot, particularly if you leave near the work.