: I’ve been struggling with the epoxy fill coats. Lots of bubbles, and an
: uneven coating. I left the garage heater on by mistake today and when I
: got home it was 85F in the garage. I put a coat of epoxy on and it’s
: smooth as glass. It was about 70F when I put the other coats on. Also, I
: didn’t have near as much trouble last year, but I was applying the epoxy
: in the summer time.

: I’m using System 3 with slow hardner.

: Dwight

Temperature does matter but it can also be the temperature of the epoxy when you apply it or the boat itself, not just the temp of the shop. Some people warm up the components before mixing when they wet out glass to reduce viscosity.
The method you use to apply fill coats may have to vary a little, the first is on a very rough surface while the next has a much smoother base, less prone to bubbles, etc. And yes. the appropriate hardener is important. S-3 recommends that the slow hardener normally be used to retard the other two in a mix to suit yr conditions, rather than straight up.