5% probably is not enough thinner. Check with the manufacturer about their recommendation too, they probably have a different, faster-drying one for spray than for brush and roll.

: After getting a miserable finish using brushes, both foam and natural brisle,
: and Captain's. I sanded the thing bare and tried my HVLP gun. I thinned
: with the recommended thinner at about 5%. It is definitely a better finish
: than my brushing job but still far from perfect. I got a little bit of
: orange peel but at least the runs and drips are not there, as they were
: with the brushing.

: I found varnishing to be the hardest part of the entire process.

: Good luck.....