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Hey Guys,

We're expecting low temps in the high 30's for the next three days/highs in the 50's & low 60's. West System Fast Hardener epoxy specs say not for use under 40 degrees. If I apply it and the temps drop does it slow/stop the cure until the temps rise or does it negatively impact the cure permanently?

Yes, I have a space heater, but I'm not confident I'm going to get a lot of heat to hold overnight in the motorbox/deck bulkhead area, especially if we get some wind.

Thanks,

JohnV8r

Highs in the 30s????? I wouldn't risk it

If it were highs in 70s, lows in 40's and I could put heat on it, I would go after it if you could get it done earlier in the day and have a few hours of the high temps before it dropped at night.

I may be conservative here - I am worried and am going to be a wimp about the cold and some goop to seal up 4 bolt holes going through my transom not curing............

John,
The fast hardener creates quite a bit of heat in the chemical process to cure the epoxy mix. Too cold and it won't chemical bond properly to the resin and cure correctly thus producing weak applications.

John, I agree with the above. adding my 2 cents... You'll need to keep it above 40 (60-70 is better) during the entire cure cycle or it could result in a hardened but weak bond. (i.e. 70 degree epoxy isn't going to bond well to a 30 degree hull, and if the epoxy or substrate gets below 40 before full cure then you could have problems) West Systems has some good articles on cold weather bonding..

Here in Maryland, I keep the hull/substrate warm with electric heating blankets, space heaters and monitor with a remote thermostat - all bought from Walmart. Keep the epoxy at room temperature when mixing, bond earlier in the day and monitor the temp for too hot or too cold through the night.

some safety considerations - I unplug all heaters, electric devices except for overhead lights and have good ventilation when I'm wiping down with acetone and I try to be real careful to not apply too much epoxy at once as it will catch fire.

Hutch

Thanks guys! I'm glad I asked. It's just typical that right when I need to do some critical glass work a cold front rolls in. I'm going to wait until the temps are right. Part of the project I'm trying to get done is the shaft log conversion to the fiberglass logs. I don't want an inferior bond on the hull below the waterline.

I love the electric blanket on the hull idea! Never thought of that.

I bought an electric blanket a month ago and have some old comforters that I was going to use as insulators. But, I decided to wait until next week in SC when our weather warms up for my work below the waterline.

BTW, I watched a Boatworks Today video on YT where Andy was warming up the epoxy to about 90F (I think) before he started mixing. If you're working in cold temps you may want to consider keeping your epoxy indoors at least to room temps.

The subject of the video was the ratio of thickening agent for epoxy.