Oxidation occurs on objects, such as plastic lawn chairs, after a long exposure to oxygen. After oxygen and water come in contact with metal, the process results in rust. With white plastic chairs it may turn them to a dull yellow. Removing the layer of oxidation requires a slight abrasive material such as an automobile polishing compound. With the right technique you can remove the oxidation without getting white particles on your clothes.
Scoop 2 tbsp. of automotive polishing compound onto a small sponge.
Turn the white plastic lawn chair upside down and wipe the legs of the chair with the compound. Rub the compound over the chair with medium pressure, loosening the oxidation.
Flip the chair right side up. Continue rubbing the chair with the compound until completely covered. Use additional compound as needed.
Set the chair on its side. Standing 6 feet from the chair, spray it with the garden hose, removing the oxidation from the plastic and keeping the residue from getting on your clothes.
Place the chair right side up and set in a sunny location to dry. Repeat the process on all the lawn chairs.