Dash Paint

I painted a dash piece with the SEMS Trim Black and it turned out fine, nice black semi gloss.
Months later, I painted a dash piece and it turned out a really flat black.
I contacted SEMS Tech Line and was told that humidity will have an effect on the paint finish and very high humidity will cause it to dry to a very flat finish.
Sure enough the part that dried to a nice semi gloss was painted in the Indiana Spring weather, cool dry air.
The part that dried to a very flat finish was painted on a hot humid Indiana Summer day.