A low power CO2 laser cutter (like the one that we use) is fantastic for cutting and engraving wood, fabric, paper, and plastics. It’s also great for engraving painted or otherwise surface coated metal, like anodized aluminum (for example, making the labels on a Maglite).
However, with only a few exceptions, a laser like this generally falls down flat if you want to cut or engrave a chunk of bare metal. One exception is that you can actually cut through metal if it’s thin enough. Another is that you can make dark marks on metal with the help of a ceramic coating compound like CerMark. CerMark is sprayed on metal, then blasted with the laser so that it fuses to the surface, leaving a dark, permanent mark. Unfortunately, a spray can of CerMark costs $60, and as it is a specialty item, it may not be easily available when you happen to need it. So what do you do if you need something like this and you don’t have it?
Searching around for alternatives, we came across this discussion at Sawmill Creek, suggesting that a $10 spray can of dry moly lube might work well, and we decided to give it a try. Dry moly lube is commonly available at industrial supply shops; we were able to locate a can of CRC brand for $12 at Grainger, only a few blocks from our workshop.
And here it is after a little more cleanup. We expect that the marks that you get out of CerMark or other brand-name ceramic coatings are a little darker and more permanent, but it’s clear that this is a viable (if low-end) method of using a low-power CO2 laser to make permanent marks on steel.