Shearwater Sport epoxy problem

Tried to glass the underside of the deck this morning.  Got the first piece on pretty smoothly - the rear half of the deck.  I'd made up 3/4 cup of epoxy.  But it did start to get pretty warm as I was finishing up the sternmost couple of feet.  So I left about a quarter cup in the container and did not quite get all the way around the cockpit

Took a lunch break.  Did a few chores.  Then went back to the boat.  This time, to attempt to forestall the premature warming, I only mixed up about a half-cup to finish up the aread around the cockpit and do the additional layers of reinforcement on the deck between the cockpit and the forward edge of the rear hatch.  Got the cockpit area done fine, then started on the rear deck reinforcement. 

Laid down the first additional piece and started pouring epoxy.  The damn stuff started heating up and stiffening up again.  So much so that it didn't thoroughly wet the second layer of cloth.  So now I've got one good layer and one not-so-good layer on top of it.  I mixed up a small third batch just to do the best I could with it. 

So...try to do anything about it, or just put the third and forth layer on top of what I've got?

It it has to be fixed, am I sanding through the white areas to get to the good bottom layer?

And is there a maximum safe quantity of epoxy that will not cook itself and give you a reasonable work time?  I assume it's related to the ambient temperature.  Where I am in Florida, it's warm now, but not hot - mid to high 70s.

Thanks guys.



4 replies:

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RE: Shearwater Sport epoxy problem

tough problem to have....

if it did not wet out, i would sand it out or otherwise remove the not-wet out piece. sanding back to the first layer should be fine.  if its not wet out, it will not perform the function it needs to perform in the composite.  the glass does not provide the strength is you are counting on if it is not properly encapsulated in the epoxy resin.

on the quantity/heating problem.  honestly, it sounds a bit strange...high 70s is warm but not particularly hot...and the quantities you are working with do not seem excessive.   a couple ideas.

  • do you work first thing in the morning or whenever the coolest part of the day is.
  • once mixed, get it out of the cup and onto the area you are working.  if you keep it in the cup, the heat can build up fast, if you get it out and immediately start spreading it.....that will buy you time from a 'its getting hot' kicking kind of event.  
  • are you using a hardener that is for hot environments like florida?  you can check the epoxy manufacturers site....but make sure you are using slow cure hardener.

hope that helps



RE: Shearwater Sport epoxy problem


   If your glass is white from lack of epoxy then just add epoxy to the areas you missed. I don't know what else would cause whiteness as you describe.

Strategies for warm weather and medium-to-fast epoxy---

Mix smaller batches.

Use a wide-bottomed container to encourage dissipation of exotherm heat- plastic gallon sized ice cream containers, or the like.

Do the big areas first, to get most of your batch quickly out of the pot. The smaller remainder won't cook as quickly as you fidget with the details.

Did I mention, mix smaller batches? -this always works.

If you feel the batch getting warm, stop using it for glass wetting -warm epoxy can still work for putty and fillets or even top coats, but it's too risky on dry glass. 

RE: Shearwater Sport epoxy problem

   H types faster!

RE: Shearwater Sport epoxy problem

I too am in humidity prone Florida. The only time the pot life is exceeded was when I got the hardener too rich........too much hardner.  I'd check your mixing technique and as the others have said smaller batches. For example you mention 3/4 cup, 6 oz.   We only mixed ten pumps.. full pumps, full travel.    No where near 6 oz.  When we needed to cover a lot of area two of us worked. One applying and one mixing.    

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