How long does it take to convert Chromium VI to Chromium III on galvanized steel?
Some galvanized steel is dipped into chromium quenches after hot-dip galvanizing. The chromium creates a passivated surface on the galvanized coating that prevents wet storage stain and white rust on the galvanized coating for a short period of time after galvanizing.
After reacting with the zinc when the newly galvanized part is dipped into the chromate quench, the chromate converts from Chromium VI (hexavalent chromium) to Chromium III (trivalent chromium). There is a small amount of Chromium VI that remains on the galvanized surface, but it converts to Chromium III shortly after being galvanized.
The AGA conducted a study on the conversion of Chromium VI to Chromium III a few years ago. That information was published as an Environmental, Health and Safety (EHS) Note and is titled Hexavalent Chromium Study. That study is available as a download below.
Hexavalent Chromium Study