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White rust - prevention and cure
Galvanized sheet damaged by white rust generally cannot be restored to its original high luster appearance.
The rust stain, depending on severity, irreversibly alters the surface characteristics of the zinc to varying degrees.Nevertheless, there are treatments that are helpful in improving the appearance, depending on the severity of the stain.
The following methods have been used successfully to treat the effects of white rust on galvanized steel depending on the severity of the staining.
For less severe white rust staining
- Rub or brush the galvanized surface with a mixture of mineral oil and sawdust. The mild abrasive action may remove the stain, although this treatment is not of much help for galvanized that displays advanced wet storage stain.
- Use a household cleanser, like Formula 409, and brush the surface.After brushing, then rinse the surface with water.
- Use a 10% (by volume) acetic acid solution to wash the galvanized surface and follow the wash immediately with a thorough rinsing with water to neutralize the surface.Use a stiff bristle brush to assist in the removal of the white rust.Ensure that you have dried the galvanized sheets before restacking them.While this treatment may remove some of the metallic luster, even in non-stained areas, it also will remove the white rust.
For more severe white rust staining
- Use a solution of 5% (by volume) of phosphoric acid in water. Add a wetting agent to the solution and brush the solution onto the galvanized sheets.Rinse the galvanized sheets immediately to neutralize the surface and then thoroughly dry the sheets.This treatment will remove some of the metallic luster, even in non-stained areas.
- Removal of white rust is probably not possible if the stain has progressed to dark grey or black in color.
For damaged galvanized sheets
- Apply a good, color matched, zinc-rich paint to restore the protective value of the zinc coating and improve the appearance of white rust damaged sheets.Thoroughly brush the surface of the damaged galvanized sheets, rinse with water, and dry the sheets before painting.After two years or so, weathering will largely remove any difference in appearance between the zinc-rich paint and the galvanized surface.
Call us today at 1-219-931-3131, email us at sales@midwestmetalfabrication.com, or send a fax using 1-219-844-8512 to get a quick quote to help solve your heavy gauge steel fabricating problems.
When a project calls for heavy gauge metal fabricating for OEM or end-user parts and components, call the rest, then use the best - Midwest Metal Fabrication! Call 1-219-931-3131 today!
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