<http://schema.org/description>
"Trivalent black passivates currently in use reflect the great strides made in appearance, corrosion protection, and solution life. All these are improved and the processes are a little more like the old two-part hex black. However, they still employ multiple additives and controllers to maintain the solution."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.pfonline.com/articles/getting-better-all-the-time>