Remove grease, oil, etc. by washing with a commercial paint cleaner. Thoroughly rinse and allow to dry. Acid and alkali contamination should be removed by thorough rinsing with clean water. Efflorescence or mould on plaster, masonry or timber surfaces must be treated. Rust, millscale, oxide deposits, loose or flaking paint or other foreign material on metal surfaces should be removed in accordance with the requirements of the chosen system, then apply primer, sealer or undercoat as required.