Temperature and epoxy

I am starting to build a dory in San Diego and have some concerns about the cool, damp weather we are having this winter.   I am building the boat on my apartment's patio under a shelter I built.  The shelter has withstood 4 inches of rain and 40 mile per hour winds during the several storms we have had this winter.  However, it is not fully enclosed and the temperatures have been from the mid 40s to the mid 60s and has been very humid. 

I saw previous threads about using shop lamps and a poly tarp tent over the boat to help cure the epoxy (which I intend to do).  My question is what are the warning signs that the cold and dampness may be negatively impacting the epoxy?

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RE: Temperature and epoxy


When I called MAS about temperatures & humidity, the rep told me I was good on epoxy down to 41 degrees (with slow hardener), and that unless I was standing in the rain, not to worry about humidity. 

However, she also said fiberglass cloth will pull humidity out of the air and hold it in the weave, which can cause problems... and that I should leave my glass sealed in a bag until I'm ready to put it on/wet it out.

In your situation, I'd say it's definitely worth a phone call (lot of $$ wrapped up in that epoxy!).  MAS: 1-888-627-3769.

Good luck,


RE: Temperature and epoxy


Your winter is our post-thaw spring. Around here those are the normal conditions for the pre-Okoumefest push to finish (and a few times for Okoumefest itself). I can tell you from personal experience that you don't have anything to worry about. Just leave the glass wrapped like Larry says (which you want to do anyway to protect it from dirt & dust), apply the epoxy when it's in the 60's, give everything a little longer to cure and enjoy the fact that the water's coming down liquid and that you can work on your boat instead of shoveling the drive.




RE: Temperature and epoxy

Thanks for both of your replies.  I keep forgetting that storms that give us rain in San Diego eventually dump snow on the east cost.

This is the first time I have worked with epoxy so I have been busy gluing pratice boards together under different conditions.  The problem I have is that I do not have a clear image in my head as to what either succuss looks like or what failure looks like.


RE: Temperature and epoxy

I have been working in my garage in New England and temperatures have been 20F to 40F the last month.  I found I could epoxy pieces together with localized heat, halogen lamps, for example but I could not seal or wet out cloth unless I got the temperature of the substrate and epoxy up to 55-60 degrees.  The viscosity of the epoxy has been too thick to spread effectively.  This is a good warning sign for me is how thick is the epoxy before I add any thickeners like a cell-o-fill or wood flour.



RE: Temperature and epoxy

Thank you all for your help and thanks to John for his post on the other epoxy temperature thread.   When I tested my practice boards, my first test was a disaster - I didn't stir the epoxy enough, mix in enough cell-o-fill or get the shop lamps close enough.  As a result the epoxy never cured and when I stress tested the board, it broke on the scarf joint.  My other two tests were successful, the epoxied scarf joints proved to be stronger than the wood and the boards broke on solid wood not the scarf joints. 

Thanks to all of your posts, I am now storing my epoxy and wood parts in my apt instead of the porch, and I know that before I start any boat wide epoxying or glassing, I will need to warm up the boat under the tarp as well as the air before I start.

 Thanks again


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