We have a built in buffet shelf in our dining room. We think it was originally made of MDF. The paint was chipping away so we sanded and repainted it. Now we are afraid that if we put anything on there long term, it will stick to the paint. I usually put frames on this long shelf and they will probably bond to the wood b/c it's newly painted. Should I cover with some kind of lacquer or polyurethane so it will dry with a nice solid finish?