Anodic treatment is a surface treatment that forms an oxide layer on the aluminum alloy. Through laser engraving, the surface oxide layer will be decomposed.
Stainless Steel (with coating or Hybrid Laser)
Stainless steel reflects most of the energy from a CO2 laser due to its wavelength. So special oxidants are required to allow the stainless steel to oxidize and darken at relatively low temperatures and darken the color. Wear work gloves when applying the coating. If you're using Hybrid Laser, the laser can engrave on stainless steel