Probably the same issue as with latex gloss paint. It naturally sprays
with less gloss than when applied with a brush. Nature of the beast.
I'd bet you aren't doing anything "wrong". Someone explained the
mechanism that dulls that type of paint when sprayed but I forgot. It
was a paint rep. that told me the details. It's NOT the typical "too
dry", "too far away" syndrome. Don't let 'em blame your technique.
It's a property of latex, and I'm betting it's a property of the
acrylic, too.

Dave

MVG wrote:

I'm using a spray gun/cup HVLP system to spray a glossy acrylic pain on
wood, and for some reason the finish refuses to gloss. When spread with
a brush, it looks great, although with brush marks. Has anyone seen
this problem before? I'm about to apply a water-based urethane to try
to get the shiny finish if necessary.