Can you use polyurethane to finish and seal a painted piece of furniture?

Question

I spray painted an entertainment center but it looks uneven...glossy in some spots and dull in others. Is is safe to use polyurethane to give it a uniform, finished look?

Answer 1

Yes, but maybe it will yellowing. Try to repaint it first use smooth stroke, never stop the spray above the surface. Also don't restart above.

Answer 2

If you sand it evenly then spread the poly on it it will be fine. Poly takes a long time to dry but after it does and the more coats you put on it will give it a deeper luster.

Answer 3

I suspect that you did not apply a sealer to the unit before you started painting it.  The wood is soaking up the volatile vehicle and giving it a spotty finish.  

I would sand the finish lightly between coats, and continue with the same paint you had been using.  The final couple of coats should be of a sheen that you want, gloss, semi-gloss, or matte.

There is no reason to "change horses in the middle of the stream" and risk damaging your finish.  Stay with the same material, just more coats of it.  The piece will be around for a while, don't rush it.