I want to paint my kitchen cupboards (they came with a Nelson Home package). They seem to be part wood and part metal. The metal is on the top, bottom and at the seams. My paint store asked if they were baked enamel. I haven't a clue. They said if it was baked enamel that I could use a latex plastic primer before I paint. Otherwise, I'm not sure. Also should I sand the metal to help the primer adhere to the metal? If anyone has any help to offer it's greatly appreciated. The cupboards are circa '76. Thanks.