One of the tubs in our new home has a few spots where the enamel is chipped away and the metal underneath has started rusting. I don't want to replace the tub yet, so how can I clean and patch the tub? Not so much concerned with aesthetics as with prolonging the life of the tub.
With one of these: Enamel Repair Kit
You simply sand out any rust in the chipped enamel, then paint on a new enamel coating. The finished repair should be permanent, and if well-done nearly undetectable.
I first use a mini wire brush,not too stiff bristles..you can sand some too,then vacuum all dust out.Then apply a rust coverter(i use OSPHO)this will"kill"and convert any remaining rust to "black"metal.Wait 24 hrs.then I tape off 1/2 inch outside of problem area(I use blue painters tape..much easier to remove than regular masking tape),then tape newspaper to cover an additional12 inches out for any overspray when I prime it),spray with oil primer from can,like rustoleum,not too heavy let dry then apply enamel final coat,2 will probably be better and last longer,id let this dry as long as possible,finished!