Polyurethane is a clear varnish that dries to a hard solid finish.
Top coat for latex painted cabinets.
Your best bet would be painting them with an oil based paint as the top finish paint as well.
This will give your piece maximum hardness and durability.
Do not apply water based polyurethane over the top of gloss latex and acrylic enamel.
On the other hand a few fresh coats of paint can go a long way toward transforming your existing cabinets for a fraction of that price.
To give painted furniture maximum protection top coat paint with 3 coats of clear coat.
It protects your wooden surfaces from scratches and prevents paint from peeling and.
For almost all dark matte paints i like to use a poly or wax as well.
If you painted your cabinets with any of these paints apply a water based poly over the top to prolong the life of the finish.
For example my entertainment center does not have a top coat but the paint itself is an acrylic emulsion paint.
How to use polyurethane over latex paint.
This sounds excessive but our top three clear coats all have very fast dry times which will cut down on the time to finish your project.
Water based polyurethane is well suited for low sheen flat eggshell or satin latex paint.
Polycrylic might help but probably not for long.