Cr(VI) Exposure from Grinding Hard Chrome Plated Steel

January 26, 2009

I am the EHS (Environmental, Health & Safety)representative of a mold-building shop. The production foreman asked me if it's safe to machine and polish blocks of steel that have been plated with chrome. Since the plated chrome is derived from the hexavalent, Cr(VI), chromic acid, I'm a bit concerned with potential inhalation hazards (the exposure limit is extremely low).

Jeffrey Murphy
Machine shop - Rogers, MN, USA

First of two simultaneous responses -- January 27, 2009

It does not matter what the chrome is derived from as long as it is chrome metal it has a valence of zero and is thus safe to grind with normal grinding precautions.

James Watts
- FL

Second of two simultaneous responses -- January 28, 2009

Jeffrey,

As plated chrome is in the 0 valence state. The only way there could be any hexavalent chrome present is if your platers have rinsed the parts very poorly and allowed the hexavalent chrome dry on the parts. This will be fairly obvious as the hexavalent chrome will be a red/brown colour, the as plated chrome should be a silvery shiny metallic colour.

Brian Terry
Aerospace - Yeovil, Somerset, UK