Epoxy Set Times vs Temperature

[FourPoints]

Last weekend I pulled the aluminum U channel that the companionway slats slide down into off to start the process of rebedding it since it has developed a small leak at the bottom when it rains heavily. When I pulled it off I noticed there were many imperfections in the fiberglass it was covering, and many points for water ingress, most of which would eventually find it's way to the bilge, and explains most of the mystery drips I've seen from places far from anywhere that should be able to drip.

Yesterday I mixed up a batch of penetrating epoxy and injected about a cup of epoxy into these little holes with an epoxy syringe. The temperature was about 50 degrees when I did this, and to help kick the mix I went slightly heavy with the hardener, and also fired up the stove to heat up the area (which was quite effective, warmed up the interior to about 75 degrees in no time). I could not however keep the temperature that warm all night.

Over night it dropped down into the low 40's, and will be back in the 50's today.

The epoxy says it's minimum cure temperature is 50, and takes 24 hours to cure. My question is did I screw up by using it when the overnight temp is lower than 50, or will the lower temperatures simply take longer to cure? I had thought that it would just stop curing while below 50, and resume the process when it warms up, but now I'm wondering if I was wrong...

 

[oliversdad]

You are correct that the curing process will simply slow down with lower temps.However adding more hardener is not recommended at least with West System brand.It will set up eventually but be careful with the mix.Barry

 

[wetass]

Second what Oliversdad wrote, but just want to emphasize the point about not deviating from the recommended ratio of hardener to resin. Epoxy is not the same as polyester or vinylester resin where you can add a bit more hardener to help it along in colder temps or lower the ratio to slow it in hot weather. With Epoxy, you want to use different hardeners (slow and fast), not change the ratios. If you do, Epoxy may never fully harden.

 

[CalebD]

What brand of penetrating epoxy did you use?

I think that it will cure, eventually. It might take a few days, a week, who knows? It may not cure optimally because of the extra hardener, but it should cure, eventually.

 

[FourPoints]

I didn't add that much extra hardener, it's pretty close to the proper ratio, I know it messes things up to be too far off.

I used the West Marine brand Penetrating Epoxy since I happened to have a bunch laying around (found it on sale for about $20 for the 16oz package, for that price I knew it would eventually get used) . http://www.westmarine.com/webapp/wc...toreNum=50218&subdeptNum=50219&classNum=50220


I don't really care if it takes all week, or even 2 weeks to cure, the boat is on the hard and covered so there is no rush, just as long as it's cured by this time next month

 

[CalebD]

Well you certainly got a good deal getting 16 oz of that stuff for $20. WM's web page lists it for $54.99 for that size.

It still think it will cure, eventually. If it still seems tacky by next weekend you could hit the areas you epoxied with a heat gun to help the exothermic (gives off heat as it cures) process of curing.

Epoxy is funny stuff when it comes to heat. Normally it gives off heat as it cures but this will not happen unless it is already at some minimum temperature. Normally you don't have to add heat if it is warm enough but you can add heat to bring it up to the minimum temperature which should help to jump start the curing process.

 

[FourPoints]

That was why I fired up the galley stove for about 45 minutes, it was certainly warm enough to get started, just hoping that it is warm enough today and tomorrow to let it finish.

 

[Hello Below]

FourPoints,

Give it time, it will cure. Several winters ago, I took out my cabin sole to refinish in the garage. Did all the sanding and cleaning required and decided to seal the back of the teak with epoxy. It flowed out nice and smooth and initially looked great. Twenty-four hours later it had not kicked. I think it was about day 8 or maybe 10 when I headed to the garage with a garbage bag, rags and lots of mineral spirits to clean up my mess. To my surprise sometime during the previous 12 hours the epoxy had cured hard. I was so relieved as I was not looking forward to the cleanup job if it was at all possible. We live in the PNW where the high for the day was around 45 and the low around 40 in the winter. The garage is just about ambient. So the moral of the story is, give it time. I think you will be all right.

 

[jibes138]

I built a small dinghy and I used to put the extra epoxy mix I didn't use in an old freezer in the garage so I wouldn't waste it. At 100 bucks a gallon over ten years ago it is too valuable to not use all of it. This worked fine, when it warmed back up it would cure like normal.