Aluminium Pre-Treatment

Aluminium substrate pre-treatment according to BS 12206 involves three main processes: chemical treatment with aqueous solutions containing either chromate ions or chromate and phosphate ions, chromium-free systems, and electrolytic conversion (pre-anodising). Chemical treatment with chromate or chromate and phosphate ions is the traditional pre treatment for architectural aluminium and provides proven corrosion protection in service and good powder adhesion. Chromium-free systems generally use chemistry based on Zirconium, Titanium or a combination of both and have proven to the performance criteria of EN 12206-1. Lastly, electrolytic conversion (preanodising) is an electrolysis process that builds a natural oxide layer on aluminium to a thickness within specified limits. All three processes must be carefully monitored and controlled for compliance with EN12206-1:2021.