I've recently had an old metal sink base sandblasted, primed & painted. What type of sealer should I use to prevent the paint from being scratched?
KMS pretty much summed it up. What determines how well a finish will last is the type of finish and the object being finished and how its used. If this was something that would take on a lot of abuse. Then an automotive type finish should have been considered. Also powder coat paints are really hard and are very scratch resistant to abuse. If you used a simply spray can type of finish or a latex type of paint. There is like Kevin said, little more that you can do.