You can improve the appearance of cast aluminium patio furniture by refinishing it with the appropriate coating. However, you need to take into consideration that cast aluminium is nonporous, which means that paint will not adhere to the surface. The cast aluminium needs to treated beforehand with a specific type of acid-based primer. This will etch the cast aluminium, effectively creating a surface more conducive for paint adhesion.
Wash the cast aluminium patio furniture with a water-based degreaser, using a coarse brush. Rinse the furniture with a water hose. Allow the furniture to dry in the sun for one to two hours.
Protect portions of the patio furniture you do not want painted by covering them with painter's tape and masking paper. Place the furniture on a dust sheet.
Wear a respirator and coat the furniture with galvanised metal self-etching spray primer. Spray at a distance of eight inches from the furniture. Wait four hours for the primer to dry.
Spray the primed furniture with acrylic enamel at a distance of eight inches. Wait four hours for the finished cast aluminium patio furniture to dry.
Add a second coat of enamel to the cast aluminium patio furniture if the self-etching primer shows through.
If you paint unprimed cast aluminium patio furniture, the finish will peel. Don't use an ordinary latex primer; the finish will ultimately shed.