Epoxy - One hour sun time equals how much less work time

General Discussion
1

I am wondering if any of you have any rules on how long you leave epoxy in the sun before mixing with hardener.

On my latest board I used the Hawaiian epoxy which was purchased from Burfords blanks at Currumbin Queensland.

For the laminating coats the epoxy was left in the sun for one hour prior to glassing, warm day early spring here temperature about 25 degrees celcius or 76 degrees farenheit, I used the slow hardener and ended up getting 40  minutes of work time.

The resin fowed nicely and was easy to work with, 3 hours later no longer tacky.

Same with epoxy filler coat on bottom, resin in sun for one hour, 40 minutes work time.

For the deck coat I left the epoxy in the sun for 3 hours and when pouring into the mixing cup noticed it was much runnier.

This time the resin went off after 30 minutes, 10 minutes less work time.

So my question is, is 5 minutes of work time lost for every hour epoxy is left in the sun, is this a reasonable ballpark number to use.

 

 

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2

so if you leave the epoxy in the sun all day and laminate in the evening, you have no work time left :wink:

serious, it’s just the temperature from the moment you mix resin and hardener and during the work time. You could choose a medium temperature of maybe 20°C during work time to loose none of the 40 minutes, and after that put the board in the sun to speed up the curing process.

There’s a rule of thumb: 10 degree more halves the curing time / working time.

Example:

20°C-> 40 min work time

30°C-> 20 min work time

40°C-> 10 min work time