Here's a quick video of a Boss HP-2436 Co2 laser engraving on stainless steel using a metal marking spray.
Simply spray your material evenly, engrave, and wipe off the excess to enable your Co2 laser to easily engrave on metals with a dark black finish. You can buy metal marking spray products at the websites below.
http://www.cermarksales.com/
http://www.thermark.com/
