Typically if you are coating with a gloss powder, the procedure is: Bake the
base color you are going to over coat with clear about
50% of total cure
recommended.
Now to apply the clear can be tricky.
Back the volts down about
1/3rd, allow the piece to drop in temp
to about 200deg F and apply the clear
lightly until the piece has an even frosted look.
Be careful not to clump or lay
the clear too heavy; it will have a tendency to sag.
Then cure at the normal rate
and temp as recommended by the manufacturer..
This should give you a perfect clear
finish.