The metal marking process using a CO2 laser is best described as a thermal bonding of a coating to the metal. These special coatings like CerMark can be brushed or sprayed onto the metal and use the heat energy from the laser to fuse the coating onto the surface of the metal.
The list of metal types compatible with the thermal bonding process is extensive. Steel, stainless steel, aluminum, pewter, chrome-plated steel, titanium, tungsten carbide, tin, and many more alloys can be marked using CerMark metal marking coatings and a CO2 laser system.
The laser marking process starts with clean and uncoated metal. Remove any and all oils that may be on the surface of the metal. Often in manufacturing there are stamping release agents or corrosion inhibitors used on metal, which need to be cleaned off. Use a cleaning solution that dries without leaving any contaminates behind, such as denatured alcohol. Soaps and other cleaning agents are acceptable to use with a final wash down using denatured alcohol.
Also keep in the mind the metal should have no clear finish or coating on it. It is mandatory that the marking compound be in direct contact with the metal. Anodized or clear lacquer finishes on the metal impede the bonding process and create spotty results.
Applying the metal marking compound can be done in several ways and is best dictated by the material being laser marked. CerMark is available in several forms, including a concentrate paste that can be brushed or sprayed onto metal. The concentrate paste is the most cost effective and is ideal for a wide range of metal types.
Another popular form is a ready-to-use spray can, which is ideal for medium-sized projects. The handy spray can applies the CerMark like regular spray paint and dries to the touch quickly. The CerMark tape form is handy for certain projects, especially flat, stainless-steel projects. The rigid nature of the CerMark tape is not very flexible and best for metal items that are flat or almost flat.
—Mike Fruciano, Coherent