As Arwyn and Brian have suggested Hammerite is best avoided in terms of the hammered enamel finishes, the pin holing Arwyn mentioned is down to the chemicals used to create the Hammered effect which causes the paint to be very thin in places allowing corrosion easy access.... However I do use Hammerite PRODUCTS to resist rust and their "ordinary" enamel paints to protect metal. It is best to get rid of rust and down to the bare metal rather than try to "cure" it, though I appreciate that is not always possible.... Good luck with your choices.
