Not directly — but with a marking spray a CO2 laser leaves a permanent mark. Here’s how, and when you need fiber instead.
Short answer
Not directly on bare metal — a CO2 laser’s 10.6 µm beam is reflected by bare metal, so it won’t mark steel, brass, or aluminum on its own. What it can do is mark metal with a marking spray or paste (CerMark, LaserBond, and similar): you coat the part, run the laser to bond the coating to the surface, then wash off the excess to leave a permanent dark mark. The one exception is anodized aluminum, which a CO2 laser marks directly by ablating the anodized layer. For fast, spray-free marking and true engraving on bare metal, a fiber laser is the right tool — see our metal-engraving guide.
Use a marking spray with a CO2 laser.
Because bare metal reflects the CO2 wavelength, the proven method is a metal marking spray or paste. You apply the coating, run the laser over it, and the heat bonds the coating to the metal; washing off the unfused excess leaves a durable, high-contrast dark mark. It is a real, production-used process for logos, serial numbers, and labels — it just adds a consumable and a couple of steps, and it bonds a mark to the surface rather than cutting into the metal.
When to use fiber instead.
If you mark metal regularly, a fiber laser is faster and needs no spray: it anneals, etches, and engraves bare stainless, aluminum, brass, copper, and titanium directly. Boss’s FM Series fiber markers are built for exactly this. The CO2-plus-spray route is best when you already own a CO2 laser and only mark metal occasionally; for volume metal marking, fiber wins. See how to laser engrave metal for the full picture.
Related questions
Can a CO2 laser engrave metal?
Not bare metal directly — the CO2 wavelength reflects off metal. With a marking spray or paste, a CO2 laser leaves a permanent dark mark, and it can mark anodized aluminum directly. For spray-free engraving of bare metal, use a fiber laser.
Can a CO2 laser engrave brass, aluminum, or stainless steel?
Only with a marking spray, which bonds a dark mark to the surface; bare brass, aluminum, and stainless reflect the CO2 beam and won’t mark on their own. Anodized aluminum is the exception and marks directly. A fiber laser marks all of these bare and is the better tool for metal.
How do you engrave metal with a CO2 laser?
Apply a metal marking spray or paste to the clean part, run the laser to fuse the coating to the surface, then wash off the excess to reveal a permanent dark mark. Test settings on scrap first. Without a coating, a CO2 laser cannot mark bare metal.
Will a CO2 laser engrave metal directly?
No — not bare metal. Direct CO2 marking only works on coated metal (via marking spray) or on anodized aluminum, where the laser ablates the anodized layer. Everything else needs a coating or a fiber laser.
Keep going
- Related: How do you laser engrave metal? · Can a CO2 laser engrave anodized aluminum? · What can a CO2 laser engrave?
- Products: FM Series fiber markers · LS / HP CO2 lasers