You cannot put oil based products over latex products...however they make water-based polyurethanes that you can apply over latex paint. They come in Satin, Semi-gloss and Gloss sheens and can be found at any Sherwin Williams store!

I don't know whether there are any rules about what you can put on top of latex paint. All I know is I use polyurethane finish on nearly everything without thinking about what the material under the polyurethane is made of. You can buy shiny or semi-gloss. The result for me is as shiny as I want it and it lasts forever, indoors. Outdoors, the sun will clobber most anything, eventually, but for indoor furniture, I wouldn't hesitate to put polyurethane on latex paint.

I painted my bedroom furniture with Para Optima Latex Paint in Melamine Finish. Everything looks great but the finish is a little to stain for me. My question is, can I put a top coat on it that will make it look semi-gloss but also be a sealant at the same time. Also, I heard there are no paint sealants for latex paint because all the sealants are oil based and latex is water based. Is that true?