If you're thinking about refinishing a steel tub with paint, there are some important factors to consider before you get started. First, unlike wood, steel is not suited for paint adhesion and requires a special type of base coat capable of etching the surface. In addition, you may need to apply a special primer, depending on the tub's condition. Finally, you will need to choose a specialist coating based on the location and function of your steel tub.
Take the steel bathtub outdoors. Wear a respirator if the steel tub is fixed indoors.
Scrub the steel bathtub with a water-based degreaser, using a coarse brush. Rinse the steel bathtub with a garden water hose. Use wet rags if the tub is fixed indoors. Wait one to three hours for the steel tub to dry.
Place the steel bathtub on fabric dust sheets.
Coat the clean steel bathtub with a galvanised metal etching primer, using a paintbrush intended for use with latex paints. Wait four hours for the primed steel bathtub to dry.
Wash the brush with water.
Coat the primed steel bathtub with an appliance epoxy paint. Apply paint to the steel tub just as you did the primer. Wait six hours before adding water to the finished steel tub.
Most steel bathtubs are galvanised with a layer of zinc, which helps protect them from rust. Occasionally this coating will fail and the tub will begin to oxidise. If your steel bathtub is rusting, you must apply a coat of iron oxide primer after you apply the etching primer. Use a red oxide primer that is compatible with latex paints.
Never use an ordinary latex or oil-based bonding primer to coat a steel bathtub, or the finish will fail.
Never paint over a bare steel bath tub, or the paint will peel.
Don't use an ordinary acrylic latex paint or oil-based enamel unless the steel bath tub is merely decorative.