Tub Re-Glazing

JPM

I am getting ready to re-glaze a couple of tubs for some rental property I own. I have tried the HOMAX spray from HD and it seems to work well on porcelain that has been prepped correctly ... except for one thing ... it does not last in areas that no longer had porcelain. the HOMAX person said to use their 2 part epoxy (sold in really tiny bottles) to coat cast iron before applying spray. The areas I need to cover are about 6-8 sq in so I would need several bottles. Have to think there is a better alternative?

Also, was thinking of spraying the whole tub with marine primer then marine paint ... seems like that might work too.

Have stayed away from other alternatives due to perceived complexity and price .... AM I NUTS? could be, let me know.

THANKS FOR THOUGHTS AND OPINIONS.