Polyester resin cure temperatures and time

[TrevorStott]

Currently our temperatures are roughly 20 degrees Celcius or 68F during the day and around 11C or 52F at night. If I'm glassing in stringers, etc can I do this at these temperatures or do I need to wait longer? My understanding is that I need 15c or 60F for poly resin to cure properly but I don't know if it needs to be above 60F for 24 hours or just a few hours. Can someone help me understand my limits and timings here?

 

[Chris51280]

According to uscomposites, they do not recommend glassing at 60F anyways. They say that there may be shrinkage and stress cracks due to temperature variation on the substrate and the resin. Best case, have everything at 75F.
I did my stringers at 40F outside and a heater inside a barn and heated up the area to 70-80F depending on the day. I mixed at 1.25%-1.5% and got around 30min work time. I turned off the heat when I was done laying down glass and the barn was able to retain some heat in the next 30min to and hour. That was enough for it to kick and harden. Seemed to work ok for me. Do double layups that will help since it has more resin and get hotter which helps in the curing. Plus it gets a better bond

 

[Woodonglass]

Yes you can do your layups at 20C. Poly starts to KICK in about 30 mins in low temps.

Poly has a chemical cure process and it does NOT​

require outside temps to aid the cure process. As LONG as you have a couple of hours above 20C and then it doesn't FREEZE within 24 hours, you'll be absolutely fine.

 

[TrevorStott]

perfect, thank you very much!