How to use CerMark: step by step

A CO₂ laser cannot mark bare metal on its own: the metal reflects the beam instead of absorbing it. CerMark solves that. It is a spray coating of fine ceramic and glass particles that absorbs the laser energy and fuses to the surface where the beam hits it. Everything the beam does not touch rinses off with water afterwards, and what stays behind is a black or dark grey mark.

The same process works on glass, ceramics, stone and slate, with the CerMark variant made for that material. This article takes you through the whole job in six steps, from a greasy part to a finished mark, with the reasons behind each step.

Marking or engraving?

CerMark marks: it adds a layer to the surface and removes nothing. Engraving cuts material away. Most people search for “engraving metal with a CO₂ laser”. Workshop CO₂ lasers, BRM machines included, cannot engrave metal. CO₂ systems that can do exist, but they are industrial installations in a different market segment altogether. On a workshop CO₂ laser, marking with CerMark is how you put a mark on metal.

The whole process on video

This video loads from Bunny Stream once you allow functional cookies.Edit Cookies

Using CerMark from start to finish: degreasing the part, shaking and spraying the can, drying the coating, marking it with the laser and rinsing off the residue

Which CerMark for which material

All of them are applied the way this article describes. They differ in the material they bond to.

Spray	Use it on
CerMark LMM-6000	Harder metals: stainless steel, steel, titanium, brass, copper, plated metals. Gives the darkest mark on stainless steel.
TherMark LMM-14	Softer metals: aluminium, chrome-plated stainless steel, silver-plated brass, gold-plated galvanised steel
CerMark LMC-6044P	Glass, ceramics, porcelain, decorative tableware
CerMark Ultra	The newest, universal variant: metals as well as glass, tiles, ceramics and slate. It covers what the three above do, but on a given material the mark can come out less black than with the variant made for it.

On glass and ceramics a spray is optional: the laser marks them without it, but the result is a dull white frost. On metal it is required. See why use a laser spray.

What you need

• The CerMark spray for your material
• Alcohol (isopropyl or denatured) and a lint-free cloth, to degrease the part
• A respirator: a half mask with 3M 60921 cartridges (organic vapour plus P100 particle filter) or an equivalent combined vapour and particle filter
• A well-ventilated place to spray
• Optional: a hair dryer or an oven, to dry the coating faster
• Lukewarm water and a soft sponge or cloth, to rinse off afterwards

Step 1: Prepare the material

The surface has to be free of grease and dust. Wipe it down with alcohol and let it evaporate. The manufacturer also lists cleaning agent films and lacquer as things that stop the coating from bonding, so a part with a clear lacquer or a protective film needs that removed first.

Do not touch the area you are going to mark once it is clean. A fingerprint is enough grease to leave a gap in the mark.

Most failed marks start here. An uneven coat or settings that are slightly off still give a usable mark; on a surface that is not clean the coating cannot bond, and nothing stays behind after rinsing. If you are not sure the part is clean enough, clean it again.

Step 2: Prepare the CerMark

Shake the can vigorously for a few minutes, until you can hear the mixing ball rattle. Then keep shaking for at least one more minute.

The coating particles settle at the bottom of the can when it stands. If they are not fully back in suspension, the coating and the solvent come out unmixed: the layer goes on unevenly, and the solids can clog the nozzle.

Step 3: Apply the coating

Spray in a well-ventilated area and wear the respirator while you work with CerMark. Download the safety data sheet for your spray from CerMark MSDSs.

Apply a thin, even layer in one or two passes:

1. Hold the can about 25 cm (10 inches) from the surface.
2. Start spraying beside the part, not on it.
3. Move across the part at a steady speed and carry on past the far edge before you stop.
4. If the bare surface still shows through, do a second pass. One or two passes are almost always enough.

Starting and stopping off the part is what keeps the layer even: the spray comes out uneven for the first moment, and a hand that slows down at the edge leaves a thicker band there. The manufacturer’s target for LMM-6000 is a coating of 20 to 25 µm, about the thickness of a thin coat of paint.

A thicker coat does not give a darker mark. It takes longer to dry and needs much more laser power to fuse all the way down to the surface, so a mark that would have worked on a thin coat comes out weak or rinses off.

Step 4: Let it dry

Make sure the coating is completely dry before you start marking. A thin, even layer dries in a few minutes; the manufacturer gives 3 to 5 minutes for LMM-6000. At 10 minutes it is dry in practically every case.

You can see when it is ready. The coating goes through three stages:

1. Wet: glossy, it looks like fresh paint.
2. Dry but dark: the shine is gone, but the colour is still deep.
3. Light grey: the coating has turned pale and matt. Only now is it ready to mark.

When you are short of time, a hair dryer dries it in seconds, or you can put the coated part in an oven at a low temperature.

A dried coating does not expire, so you can coat parts ahead of time. Some of our customers coat a batch weeks in advance and keep it in a storage rack until it goes on the machine, with good results. The condition is that nothing touches or scratches the coated area in the meantime: wherever the coat is damaged, the mark will have a gap.

LMM-6000 dries to a hard coat that you can handle and stack. LMC-6044P and LMM-14 dry to a powder that marks with a single touch, so store parts coated with those so that nothing rests on the coated face.

Step 5: Mark

The coating only fuses when it gets enough energy per square millimetre. That makes CerMark a high-power process: expect a lot more power, or a lot less speed, than you would use for engraving wood.

Settings depend on the laser, the lens, the material underneath and how thick the coat is, so test first:

1. Mark a small grid of squares on a scrap piece or on the back of the part, each with a different speed at the same high power.
2. Rinse the test (step 6) and pick the square with the darkest, most even mark.
3. Use that speed for the job.

Rules that hold for every machine:

• Thicker coat, more power. A thin coat needs less power for the same result, which is another reason to spray thin.
• Focus on the surface of the part. The finer the spot, the higher the energy density. See finding true focus.
• Use a fine interval, the distance between engraving lines, of about 0.06 mm. Gaps between the lines show as stripes in the mark.
• Glass needs less power than metal. Too much heat can crack or chip a glass surface. Start low and work up.

How to read a test after rinsing:

What you see	Cause	What to change
Nothing stays on after rinsing	Surface not clean, so the coating could not bond	Degrease again, see step 1
The mark rinses off partly or looks faint	Not enough energy	Slow down or raise the power
Patchy or blotchy mark	Uneven coating, or the can was not shaken enough	Shake longer, spray a thinner and more even coat
Lines visible in the mark	Interval too large	Lower the interval
Grey or brown mark instead of black	Too much energy, the coating burns away instead of fusing	Speed up or lower the power
Gaps where the part was touched	Grease on the surface	Degrease again and do not touch the area

Marking produces smoke, like any laser job. Run the extraction: laser fumes and extraction.

Step 6: Rinse off the residue

After marking, rinse the unbonded coating off with lukewarm water and wipe it with a soft sponge or cloth. Only the fused mark stays behind. The residue can go down the drain with the rinse water, according to the manufacturer.

How long does the mark last?

The mark is fused to the surface, so it does not wash or rub off in normal use. It does wear slowly over the years, along with the surface it sits on, and releases fine particles as it wears.

• Our experience: after 10 years a mark is still on the part and still readable, as long as the text is not too small. We expect a readable life of roughly 10 to 20 years, which is why we call the mark semi-permanent.
• The manufacturer calls the mark permanent and resistant to acids, bases, solvents, heat, cold, salt spray and weathering.

Two things shorten the readable life: abrasion, such as a tool that is handled or cleaned a lot, and small text, where a little wear already makes characters unreadable. If a mark has to stay readable for longer than this, or at a very small size, CerMark is not the right process for it.

Not for medical use or surfaces that touch food

Because the mark releases particles as it wears, CerMark is unsuitable for medical devices and instruments, and for any surface that comes into contact with food or drink: the inside or rim of a glass or mug, the top of a plate, cutlery, cutting boards, food processing equipment.

Decorative glass and ceramics are fine, as long as the mark sits where food and drink never come and the item does not go in the dishwasher, where loosened particles could end up on other surfaces. A wine bottle marked on the outside, a glass or ceramic flower pot and decorative tableware are all suitable.

Storing the can

When you have finished, turn the can upside down and spray until nothing but propellant comes out. That clears the coating out of the nozzle, so it does not dry in it and block the can.

Store the can lying on its side, in a dry, dark place between 5 °C and 35 °C. Standing upright, the solids settle into a lump at the bottom that is hard to shake loose; on its side they spread out and mix back in more easily.

CerMark has a limited shelf life once the can has been opened. Buy the amount you will use.

On a BRM machine

A BRM CO₂ laser marks with CerMark like any other CO₂ laser, with one rule we hold to firmly: never mark metal without a laser spray. The beam heats the metal until it melts, and the molten metal reflects the beam back along the optical path to the laser source. Damage caused that way is not covered by warranty.

Colouring the metal does not prevent this. Paint or a marker burns off under the beam, the metal underneath melts, and the melt reflects the beam just the same. Use a laser marking spray, which is made to absorb the beam and bond to the surface.

Starting parameters:

• Stainless steel with CerMark on a 100 W machine: 85 % power, 500 mm/s, 0.06 mm interval. From the indication parameters for engraving, 100 W CO₂. For other materials and power classes, check the BRM material library for LightBurn.
• Treat it as a starting point and run the test grid from step 5. Each laser source is different, and a thicker or thinner coat shifts the result. The general method for dialling in a material is in how can I find the right parameters for my material?
• Engrave with the 50.8 mm lens: it gives the smallest spot, and so the highest energy density.

On a BRM 90130-X or BRM Budget 90130-X metal laser, mark CerMark in acrylic mode, with the lens you use for wood and acrylic. Metal mode adjusts the focus height automatically and is not meant for marking. See what metals can you cut with the BRM 90130-X?

We supply all four sprays in the table above. For the right spray for your job, or help when a test does not come out, create a ticket.