plating, anodizing, & finishing Q&As since 1989
Rusting of bricks that have high iron content
June 11, 2012
Q. It has been suggested that Queenland bricks of light colour should be cleaned with HCl at 20:1 ratio due to the high iron content in the brick. Bricks are usually recommended at 10:1
My question is what pH level would be required to minimise rust stains in the bricks, and wouldn't they rust regardless due to rain water?
- Sydney NSW Australia
A. Dear Gary,
Bricks have a high iron content, but they have iron salts and iron oxide, not iron metal. They don't rust anymore, as they are composed by some oxides. With hydrochloric acid you "clean" from the surface some of the excess ferric oxide.
At pH 2 you may be able to dissolve some iron oxide, but you must maintain that pH level through the immersion of the brick... A 1:10 is somehow a good choice, try 1:20 if the first is too aggressive.
The bricks will not rust with rainwater or any other rusting agent!
Hope you can solve your issue. Best regards,
- Cañuelas, Buenos Aires, Argentina