Laser Engrave Over 50 Different Materials

You need a special spray to mark metal. The laser won’t actually leave a mark on metal. If you have anodized aluminum, the laser will burn away the color layer. Go to the search in the top right and search for “cermark.” You should find plenty of info on marking metals, and the dos and don’ts with that.

Actually, I found another post from the original poster:

You can see he used something on the metals.