Question from USA:
We had galvanised corugated sheets for roofing. Some of them started rusting from edges and some of them had white rust on them. Can you suggest any repair procedures so that I can reuse those sheets.

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Expert Answer:
Kishor,

The white rust will end as soon as the panels are unstacked and normally will wash off with a nylon brush, soap and water. The edge rust is another issue however. The edges are the raw cut sides and ends of the panels. In the open air the zinc will run down the panel and across the raw edges carried by rain water and minimize this occurance. Stacked however this may not occur.

If they are still stacked you should be able to wire brush or steel wool the edges and then apply a "liquid galvanizing" to the panel ends and edges. If they are already instaled the process is a bit more difficult to remove the existing rust and apply the liquid galvanizing. This may take masking, cleaning, re-masking, coating and a bunch of tedious labor.

Hope this helps,

Dale Nelson Roof Hugger, Inc.