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Rust proof coating on mild steel

We are in the process of developing an antenna for outdoor application. This requires mounting accessories which are made in mild steel. We are unable to find a rust proof coating for this. We have tried zinc plating and then powder coating which is not working out fine. We have to subject these items for salt spray test. Pl. provide a suitable solution.

Rao MS
telecom division. - Hyderabad, Andhra Pradesh, INDIA
2001

Dear Sir,

There is no such thing as a rust proof coating. To prevent rusting, the mild steel must first be cleaned and then pre-treated. This enhances the adhesion of the coating which prevents moisture getting through to the substrate and causing rust. The two coat system you are using at the moment is perfectly adequate for the end use. I would suggest looking at your cleaning process and pre-treatment process. If you get these two processes correct there would be no need to zinc prime you could just use a polyester powder.

Hope this helps.

Drew Devlin
- Lincolnshire, UK
2001