Epoxy curing vs. temperature

[xantipo]

I just finished the floats and I’m preparing the mold frames for main
hull planking.
I have however some questions about the behavior of epoxy curing under
lower temperatures as we approach cooler weather. I’m particularly
worried about temperature cycling during the night/day period.
In my location ( Northern Portugal) I’m still getting temperatures in
the upper 20’s C but during the night time it call fall as low as 15
degrees and as winter sets in these values will come down gradually.
The question is if it’s ok to do the lamination and initial cure ( 4
hrs) in the 18-25 C range even though temperatures may fall during
the night before they return to the 18-25 C the next day.
Although it can get cold in my location (usually never under 0C during
the night) , there will be many days where day temperatures will hit
the low 20’s.
I’ve been trying to get some information about this issue on the net
but haven’t been able to find anything acceptable.
I know that some of you working in higher latitudes use space heating
to be able to work during winter and I’d like to know if the heat is
used only during lamination and initial curing or if it’s left on
during the full curing period.

[simon]

> I have however some questions about the behavior of epoxy curing under
> lower temperatures as we approach cooler weather. I’m particularly
> worried about temperature cycling during the night/day period.
> In my location ( Northern Portugal) I’m still getting temperatures in
> the upper 20’s C but during the night time it call fall as low as 15
> degrees and as winter sets in these values will come down gradually.

My 2 cents worth and bear in mind I don't have alot of experience is
that my biggest problem with cooler temperatures was that when the
temp got down below 15 Deg the resin would become quite thick and was
hard to wet out the fabric properly. The temperatures I have had here
have been around the 15 to 20 on a good day then falling to 2 or 4 in
the night. The resin still went off but just took a while (a few days
in some cases) for it to get hard enough to sand without clogging up
the sand paper. I have been using Nuplex R-180 epoxy resin and the
instructions that came with it said a minimum of 15 deg for the
application of the resin and to increase the clamping time with lower
temperatures when using with fillers.

Probably best to contact the manufacturer of the resins if you can as
they are all different and some do require higher temps to cure
properly

Cheers
Simon

[Grant Kinsman]

I've had good success working at 15C outside in the garage.  In the past I applied local heat but now I just use a faster hardener.  There are some comments at the below link.

http://www.westsystem.com/ss/problem-solving/
Grant

--
Grant Kinsman

[Luis Matos]

Thanks for the feedback.

 

In the meantime I came across a document http://www.jamestowndistributors.com/userportal/document.do?docId=235&title=West+System+Cold+Weather+Bonding that in my opinion addresses the issue quite well.

 

My doubt was not so much about working at low temperatures since , down to a certain limit, with an adequate hardener it's possible to work at low temperatures. I was mainly worried about temperature cycling from 18-25C during day time, when lamination and curing is normal, to 5-10C during night time  when , for the given hardener system, the curing will nearly come to a halt. According to the document mentioned that isn't a problem since the curing process will resume as temperatures reach normal levels the next day. A warning is however issued regarding the potential for condensation build-up due to different temperatures between surfaces and work space, which can be avoided by letting surfaces reach room temperature before lamination.