Can you use a semi gloss white latex paint , (to paint interior trim) with this unit ? Does it need to be watered down at all?

The Control Painter will spray semi gloss latex paint. It may need some thinning, around 5-10%. Just enough to flow well through the nozzle. Some latex paints will spray just fine without thinning though so you can try it either way. For further help give us a call at 800-328-8251. Thanks for your inquiry!