This code covers the essential pretreatment processes required for non-ferrous metals like aluminum, zinc (galvanized iron), copper, and lead before painting in buildings. It details cleaning, degreasing, mechanical roughening, and chemical conversion methods (such as wash primers) to ensure proper adhesion and long-term durability of the paint film.
Code of practice for the painting of nonferrous metals in buildings, Part 1: Pretreatment
Quick Reference Values
Weathering period for new untreated galvanized surfacesminimum 6 months
Wash primer (etch primer) recommended dry film thickness10 to 15 microns
Flash-off time for solvent degreasinguntil completely dry
Practical Notes
Never paint fresh galvanized iron directly; it must be allowed to weather for several months or be treated with a mordant solution/etch primer.
Ensure all protective oils or temporary coatings on aluminum extrusions are completely removed by solvent degreasing before applying etch primers.
Avoid using strong alkaline cleaners on aluminum as they can etch and damage the surface uncontrollably.