Metal kitchen cabinets are a throwback to the 1940s. They were constructed as modular units so that homeowners could buy the cabinets in pieces as they could afford to add on to their kitchen. Stumbling upon a set of these vintage cabinets is a fun find. The cabinets will easily complement any retro style design you are trying to create. Rust is the biggest challenge with vintage metal cabinetry. Removing the rust will create a smooth surface that will accept new paint.
Clean the cabinet thoroughly with an ammonia-based cleaner and a rag. Remove all residues from the surface.
Brush the metal briskly back and forth with a steel-bristle brush. This will knock loose the majority of the rust.
Sand the cabinets with medium-grit sandpaper to remove additional rust. Sandpaper will work around corners and curves.
Spray the cabinets with phosphoric acid. Phosphoric acid will turn any unseen rust into iron phosphate. Let the acid work on the cabinet overnight.
Brush the iron phosphate crust that formed overnight with a steel-bristle brush. This will knock loose all remaining rust.
Apply a thin coat of oil-based primer to the cabinets with a smooth foam roller. Choose a bonding primer formulated for metal surfaces. Let the primer dry.
Pour oil-based paint into a paint pan. Roll a smooth foam roller through the paint, removing the excess paint from the roller. Apply the paint to the cabinets in a thin coat. Let the first coat dry. Apply a second and third coat, using the same technique.