Metal finishing Q&As since 1989



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Re-galvanizing metal molds for concrete

October 26, 2011

First let me say that I think this web site is a real value to the industry! It takes a ton of work to put a program together like this and I admire your efforts. I am a consultant for the concrete industry and I have been tasked with surface coating concrete panels. These panels are 24" x 24". The mold for the panel is galvanized steel. It has a π" lip that is bent over and establishes how much concrete to pour into the mold. This lip is visible after the concrete is cured and does not serve any purpose other than a gauge for how much concrete is cast into the frame area. The topical treatment that I have been testing has posed a potential problem. You see, when I prepare the concrete for a topical treatment, I have to mechanically grind and sand the top of the panel. During the sanding process, the tool rides on the metal lip and removes the galvanized coating. The metal looks great all shiny silver but we have created a problem by removing this rust inhibitor. The panels are subject for being placed in high moisture areas and we need the galvanized treatment to prevent rusting from occurring. I have tried to prepare the concrete in other ways but have not been successful at all. We have to use abrasives to open the concrete up so it will properly receive the surface treatment. I was wondering if there is some simple type of a galvanized process/system I could do in my facility to rework these panels. Hope you can help.

Andy Bowman
Product Developer - Bluffton, Ohio, USA

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October 26, 2011

Sir:

I do not understand your question. Perhaps a photo or two could help me understand.

Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

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Photo posted October 27, 2011

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October 29, 2011

I think I understand the problem...?
You dress the surface of the concrete in a galv steel mould and in doing so you remove the galvanizing, and the exposed steel rusts??

You can't regalvanize the steel with the concrete in it.. would not work.
You need to find a way to avoid removing the galvanizing. Either localised grinding of the concrete, avoiding the steel, or masking the steel.

But I can't see how either would work.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

We use brush plating on a regular basis to plate cadmium and nickel plating. It may be possible to replace the zinc using a brush plating system.

Don Davis
- Tulsa, Oklahoma, USA
November 3, 2011