In Part 1 we established that colour on stainless steel comes from controlling the thickness of an oxide layer grown by the laser — and that the thickness is measured in nanometres. In this part, we look at the four settings in LightBurn that control that process, and what adjusting each one actually does.
The four parameters are frequency, pulse width, speed, and power. They don't all do the same thing, and understanding which ones control hue versus which ones control saturation will save you a lot of wasted blanks.
Controls how many laser pulses hit the surface per second. Higher frequency means more pulses, more energy delivered, thicker oxide layer.
Controls how long each individual laser pulse lasts. Longer pulses deliver more energy per pulse, affecting oxide depth and colour saturation.
Controls how fast the laser head moves across the surface. Slower speed means more pulses land in each area, delivering more cumulative energy.
Controls the energy output of each pulse as a percentage of the machine's maximum. Scaled by wattage — a 60W machine at 50% delivers the same energy as a 30W at 100%.
Frequency and pulse width — the hue controllers
These are the two settings that determine which colour you get. Think of them as the "tuning" parameters — you dial them to a recipe for a specific colour, and then leave them alone while you adjust the others for your particular machine.
Frequency works by controlling how many pulses per second reach the surface. At higher frequencies, pulses arrive so quickly that the surface temperature stays elevated between pulses — the oxide layer builds up steadily. At lower frequencies, the surface has time to cool slightly between pulses, and the oxide grows differently. This change in thermal behaviour is what shifts the colour.
Pulse width controls how long each individual pulse lasts — measured in nanoseconds, which are billionths of a second. A longer pulse lingers on the surface, driving more energy into a smaller area. In colour marking, pulse widths typically run from 2 ns (very short, very precise) up to around 200 ns for certain effect recipes. Most stainless colour recipes sit in the 2–60 ns range.
Frequency is the primary hue dial. These are approximate ranges — exact values depend on your source, lens, and pulse width. Always verify on your own machine.
Speed — saturation and consistency
Speed controls how long the laser dwells over each point on the surface — not directly, but as a consequence of how fast the scan head moves. A slower scan means more pulses land in each area, more cumulative energy is delivered, and the oxide layer grows thicker and more evenly.
Increasing speed beyond a recipe's recommendation typically shifts colour toward the lighter, bluer end of the spectrum and reduces saturation. Reducing speed below the recommendation risks overheating the surface, which can produce a washed-out or inconsistent result — sometimes called "burning through" the colour.
Power — your wattage matters here
Power is expressed as a percentage of your machine's maximum output. This is the one parameter that must be scaled when moving between different wattage machines — a 30W machine at 80% power and a 60W machine at 80% power are delivering very different amounts of energy to the surface.
The scaling formula is straightforward:
Adjusted power % = Original % × (Reference wattage ÷ Your wattage)
So if a 30W recipe calls for 80% power and you have a 60W machine: 80 × (30 ÷ 60) = 40%. Your 60W machine at 40% delivers roughly the same energy as the 30W at 80%.
Importantly, power does not change which colour is produced — it affects saturation and consistency. Too low and the colour is faint or non-existent. Too high and the surface overheats, producing muddy or uneven results. The right power level is the one that produces a clean, saturated result without signs of burning.
Select your machine wattage to see power percentages scaled from the 30W reference recipes. Frequency, pulse width, and speed stay fixed — only power changes.
| Colour | Power (min–max) | Frequency | Pulse width | Speed |
|---|
⚠ flags indicate power at or above 100% — the colour may appear with reduced saturation; run at 100% and test.
Values are starting points, not guarantees. Results depend on your machine, lens, steel grade, and surface finish. Always run a test card first.
Frequently asked questions
Which MOPA parameter has the biggest effect on colour?
Frequency and pulse width together determine which colour you get. Frequency controls how many pulses per second hit the surface; pulse width controls how long each pulse lingers. Change either one and the colour shifts. Power affects saturation and consistency, not the hue itself.
Does wattage affect which colours a MOPA laser can produce?
No — wattage does not change which colours are achievable. A 20W and a 100W MOPA laser using the same frequency and pulse width settings will produce the same hue. The difference is that higher wattage machines need lower power percentages to deliver the same energy, and they can mark faster overall.
What happens if I increase speed too much during colour marking?
Increasing speed reduces the dwell time of each pulse on the surface, which means less energy is delivered per unit area. The oxide layer grows thinner, colours shift toward the blue end of the spectrum, and saturation drops. Very high speeds may produce no visible colour at all.
Why does my MOPA colour marking look different from the reference chart?
Reference charts are calibrated on a specific machine, lens, and steel grade. Your results will vary based on your machine's actual output power, lens focal length, steel grade and surface finish, and even ambient temperature. Use the reference chart as a starting point, then adjust using the test card. See our MOPA Colour Reference Chart for downloadable test cards.