The One Metal A CO2 Laser Handles Beautifully

Most makers are told that CO2 lasers do not do metal, and for bare steel or raw aluminium that is broadly true — the beam reflects and the heat conducts away faster than you can deliver it. Anodized aluminium is the exception, and it is a genuinely profitable one. The anodic layer is a hard, porous oxide coating sitting on top of the metal, and a CO2 beam interacts with that layer rather than the metal beneath, lifting or bleaching it to leave a permanent light mark against a coloured background.

That is why anodized blanks are the standard material for pet tags, name badges, keychains, instrument plates, promotional goods and industrial labels. The mark is not a coating you can scratch off; it is a physical change in the surface layer, which means it survives handling, weather and washing.

Understand What You Are Actually Marking

The anodic layer is thin, typically measured in microns, and it is dyed. Your job is to remove or alter just that layer without damaging the aluminium underneath. Too little energy and you get a faint, patchy smudge that disappoints the customer; too much and you can cut through the layer into bare metal, producing a dull grey mark with poor contrast and a slightly recessed feel.

Key properties to keep in mind:

• Contrast comes from the difference between the dyed surface and the exposed layer beneath
• Dark anodizing (black, navy, deep red) gives the strongest contrast with a light mark
• Clear or silver anodizing marks poorly on its own; use a marking additive instead
• Hardcoat or thick anodizing needs more energy and often a second pass
• Anodized coatings vary between suppliers, so test every new batch

Buy blanks from reputable suppliers and ask whether the anodizing is dyed or colour-anodized, because that changes how much energy you need. Keep samples from each supplier with the settings that worked taped to them; that reference board will save you hours over a year.

Blank Prep: Clean, Flat And Securely Held

Surface contamination is the number one cause of uneven marks. Anodized sheet arrives with machining oils and fingerprints, both of which change how the surface absorbs energy and produce blotchy, unpredictable results.

A reliable prep routine:

• Degrease with isopropyl alcohol and lint-free cloth; wear cotton gloves afterwards
• Do not sand or abrade the surface; you will remove the layer you intend to mark
• Check the blank is flat; bowed tags lift out of focus and lose sharpness at the edges
• Secure thin blanks with low-tack tape, a vacuum table or a custom jig — never rely on weight alone
• For curved items such as anodized tumblers or flashlights, use a rotary attachment and index the artwork carefully

Jigs pay for themselves quickly in metal work. A simple plywood fixture with a recess cut to the exact blank size lets you drop in twenty tags, engrave them all, and lift them out without re-measuring. Cut the recess with your own laser, add a finger notch for removal, and label it with the blank part number.

Settings, Focus And Dither Choices

Anodized aluminium responds best to a fast, energetic mark. Because the layer is thin, dwell time is your enemy: slow speed or high overlap builds heat in the substrate and softens what should be a crisp edge.

Practical starting ranges for a home workshop:

• Speed: 300–600 mm/s for raster marking on a mid-power machine
• Power: 40–70%, adjusted so the mark appears light and clean rather than grey and recessed
• DPI: 300–400 for text and logos; 200–250 for photographic images
• Dither: ordered or halftone patterns give the crisp engineered look; Jarvis works for photos on dark anodizing
• Focus: exactly on the surface; a defocused beam is the fastest way to a blurry, low-contrast mark

Focus discipline matters more here than on wood, because the difference between a sharp mark and a fuzzy one is a fraction of a millimetre of table height. Re-focus whenever you change blank thickness, and check focus at all four corners of a full-bed jig — most hobby tables are not perfectly level.

Run a test grid on every new batch: a column of increasing speed and a row of decreasing power, then choose the cell with the brightest, cleanest mark. Photograph the grid. Over a few months you will build a settings library that makes quoting and production almost automatic.

Contrast Tricks: Marking Sprays And Fill Options

When the natural mark is not strong enough, or when you need to mark clear or silver anodizing, a marking additive is the answer. These are sprays or pastes applied before engraving that bond to the metal under the beam, producing a dark, durable mark on otherwise uncooperative surfaces.

• Clean and degrease the surface first; additive will not bond through oil
• Apply a thin, even coat — thick coats flake and produce inconsistent density
• Let it dry fully, then engrave; remove the residue with water and a soft brush
• Expect to use lower power than for direct marking, since you are fusing a coating rather than bleaching a layer
• Always test on scrap from the same batch, because coating thickness changes the result

For coloured anodizing you can also add contrast after engraving by rubbing a contrasting paint or wax into the mark, though this is less durable than a fused mark and is better suited to decorative items than to tags that will see real wear. Vapour-blasting or a light abrasive pad on the surrounding surface can increase apparent contrast on large panels, but test it, since it dulls the anodized finish.

Products Worth Making And How To Price Them

Anodized aluminium supports a tight, high-margin product range that requires no finishing, no sealing and almost no cleanup — a genuine advantage over wood and leather in a small workshop with limited space.

• Pet ID tags: the classic. Deep engraving, high contrast, weatherproof, and customers reorder
• Luggage and bag tags: personalised, durable and frequently bought in sets
• Name badges and desk plates: steady corporate and club orders, often repeat business
• Keychain tags and bottle openers: low material cost, strong impulse-buy pricing
• Promotional goods and branded giveaways: bulk orders for local businesses and events
• Industrial labels and equipment plates: higher volume, lower unit price, very repeatable

Pricing should reflect how little labour these items need. A blank tag costs very little and takes a minute or two of machine time, but the value is in durability and personalisation. Multiply landed blank cost by four to six for single personalised items, offer volume breaks at ten and fifty units, and build a simple quote sheet so local business enquiries can be answered in minutes rather than days.

FAQ

Q: Why is my engraving uneven or patchy across one tag?

Uneven marks usually come from surface contamination, poor focus or a warped blank. Degrease with isopropyl alcohol, verify focus at all four corners of the piece, and use a jig or tape to hold the blank perfectly flat. If the pattern follows a regular band, suspect an unlevel bed or a loose gantry rather than a power problem.

Q: Can I engrave bare, unpainted aluminium with a CO2 laser?

Not effectively on its own. Bare aluminium reflects most of the CO2 beam's energy and conducts heat away quickly, so you get little or no mark. Use a metal marking spray or paste designed for this purpose, or switch to a fibre laser source for direct marking on raw metal.

Q: How durable is the mark, and will it fade outdoors?

A properly made mark through the anodic layer is extremely durable — it is part of the surface, not a print sitting on top of it. It resists abrasion, sunlight, salt water and dishwasher cycles far better than printed or painted labels, which is exactly why anodized plate is the standard for outdoor equipment labels.

Add Metal To Your Product Range This Month

Order a small mixed pack of coloured anodized blanks, cut a plywood jig to fit, and run a speed-and-power grid on each colour. Keep the winning tiles as your reference and you will have a new, no-finishing product line ready to list by the weekend. If you are comparing machines for this kind of detailed marking work, review bed sizes and power options in the Redsail Laser cutter range.

For larger-format production work, see the HF Laser cutter range.