LaserCanvas
Marking metal without a fibre laser
A CO2 or diode cannot cut bare metal, but it can remove a coating from one. Anodised aluminium marks beautifully, powder coat burns off to bare metal, and marking sprays bond a dark layer to steel. All three mark the surface — none of them engrave into the metal itself.
The distinction that matters
Metal reflects and conducts. A hobby CO2 or diode does not deliver enough concentrated energy to melt steel before the heat has spread away, and much of the beam bounces off. What these lasers *can* do is interact with something sitting on top of the metal.
- Fibre laser — absorbed by metal itself. Genuinely engraves into it, and cuts thin sheet. A different machine, not a setting.
- CO2 / diode — mark coatings on metal. The metal is a backing, not the material being worked.
The three methods
| Method | What happens | Result | Works with |
|---|---|---|---|
| Anodised aluminium | The dye in the anodic layer is bleached | Crisp white-on-colour, permanent, no consumables | CO2 easily; diode on dark anodising |
| Powder coat / paint | The coating is burned away | Bare metal showing through the colour | CO2; diode with more passes |
| Marking spray | A compound is fused to the surface | Dark grey-black mark on bare steel | CO2 reliably; diode inconsistently |
Anodised aluminium
The easiest and most satisfying. Anodising is a porous oxide layer that has been dyed; the laser bleaches the dye without removing the oxide. The mark is inside the protective layer, so it does not wear off, and no coating or consumable is involved.
Run it like a fine engrave: low power, high speed, and a tight line interval. Too much power damages the oxide layer and gives a grey, muddy mark instead of a clean white one.
Powder coat and painted metal
Burning the coating away leaves the metal beneath showing. Tins, tools, painted signage and powder-coated panels all work. The contrast depends entirely on the coating colour against the metal — black powder coat on aluminium is excellent, white on aluminium is nearly invisible.
Marking sprays
A spray or paste applied to bare metal, lasered, then washed off. Where the beam hit, a compound bonds permanently to the surface. This is the only one of the three that marks bare steel.
- Apply thin and even — thick coats mark patchily.
- Let it dry fully before lasering.
- It works best on steel and stainless; results on aluminium are poorer.
- It is a consumable, and not a cheap one.
Settings, as a starting point
| Target | CO2 (~50 W) | Notes |
|---|---|---|
| Anodised aluminium | 15–25% power, 1500–2500 mm/min | Raise speed if the mark goes grey |
| Powder coat | 40–70%, 800–1500 mm/min | Enough to clear the coating, not to heat the metal |
| Marking spray | 60–90%, 300–800 mm/min | Usually wants slower than you expect |
What you cannot do
- Cut any of it. These are surface marks on a material the laser cannot get through.
- Engrave depth into metal — that needs fibre, and usually many passes even then.
- Mark bare aluminium without help. It reflects, conducts heat away fast, and has no coating to work on. Anodise it or spray it.
- Mark clear-anodised aluminium with much contrast. There is no dye to bleach, so the result is faint.
Common questions
Can a CO2 laser engrave metal?
It can mark coated metal — anodised, powder-coated, painted, or treated with a marking spray — by acting on the coating rather than the metal. It cannot engrave into bare metal or cut it. That needs a fibre laser, which is a different machine rather than a different setting.
Can a diode laser mark stainless steel?
Only with a marking spray or on a coated surface, and results are less consistent than with a CO2. Bare stainless reflects most of a diode’s blue light and conducts the rest away. Anodised aluminium in a dark colour is the diode-friendly metal to start with.
Why is my anodised aluminium marking grey instead of white?
Too much energy. The goal is to bleach the dye, not damage the oxide layer, so raise the speed or drop the power until the mark turns crisp and white. If it is faint rather than grey, the anodising may be clear rather than dyed, in which case there is nothing to bleach.
Is it dangerous to put metal in a laser cutter?
Reflection is the risk, particularly on a CO2 with polished or bare metal, because the beam goes somewhere unintended and can damage the machine or hit you. Coated and anodised surfaces scatter far less. Never fire at a mirror finish, and keep the lid closed.