Right, not really an enamel.
You spray this product onto a metal or glass surface, laser it, then wash off the part that was not hit with the laser. I saw this used at TSMP on metal and the result was very good. The woman using it recommended it.
I got a 6oz bottle of the spray on Thermark Laser Marking Material LMM14 Black from the manufacturers web site [url]thermark.com[/url] for $62 plus $11 shipping UPS. Not cheap.