I believe the can says not to thin it. I found it plenty thin enough to spray with a pretty low-end sprayer. I have heard people say they have thinned with 10% water to extend the dry time, but I can't speak as to their end results. Mine came out great (cabinets)
—— Tech Guy
If your careful when mixing, as to not force bubbles into the mixture you should be fine.
—— David B.
I have used it on white water based enamel painted cupboards. I found that if you put it on after a few hours of drying time for the paint, it will yellow. If you let the paint dry for a few days, it stays crystal clear. it depends on temperature and humidity also. Try it in an inconspicuous area first.