The color engraving technology enables multi-color effects on specific materials. To achieve effects like the one shown below, you can use xTool F2 Ultra UV, which supports color engraving of vector fill images and bitmap objects.
Note: To use the color engraving feature with F2 Ultra UV, upgrade xTool Studio to V1.8 or later. The processing files and effect examples provided in this tutorial are based primarily on UV laser color engraving on 304 stainless steel. You can also use the same method to explore color marking on other metals, such as brass and titanium.
Importance of color engraving settings
Color formation mechanism on stainless steel
- Oxide coloration
Under laser irradiation, stainless steel's metallic elements produce colored oxidation products. - Transparent oxide film (thin-film interference)
A transparent oxide layer forms, creating color through light interference effects.
Key findings & recommendations
Minor variations in power, focus, or energy can significantly alter the engraved color. For consistent results, calibrate personalized color-engraving parameter settings based on your device’s performance. Once saved, these settings can help to streamline future engraving workflows.
Before color engraving
Color engraving results can be affected by multiple factors, including laser energy, material type, ambient humidity, and temperature fluctuation.
In this case, you're advised to first test your material with a parameter array to identify desired colors, then record and save the corresponding settings for consistent, high-quality output.
1. Test color engraving with an array
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Test array in xTool Studio | Actual processing results on the material |
(1) Download the test array file and open it in xTool Studio.
Test array for xTool F2 Ultra UV
(2) Use 304 stainless steel (SUS304) and process it after focusing and conducting the necessary device settings in xTool Studio.
If you use xTool Studio for the first time, you can see Process on Flat Surface with xTool F2 Ultra UV for reference.
Note: To ensure optimal results, please place the objects to be engraved within 60 x 60 of the center of the baseplate.
(3) After processing, evaluate the results and proceed as follows:
- If satisfied with a color outcome in a specific grid, mark down those parameter settings, including the processing speed and power.
- If seeking improved colors, locate the target color and its corresponding processing speed and power. Then create an additional bidirectional gradient test array by adjusting settings in increments or decrements of 0.5% power and 50 mm/s speed.
For example, to optimize cyan coloration (currently set at 16% power and 600 mm/s speed), generate an additional test array using these parameters as your baseline, then systematically adjust values in: - Power: ± 0.5% increments (e.g., 15.5% or 16.5%)
- Speed: ± 50 mm/s increments (e.g., 550 mm/s or 650 mm/s)
2. Set up a personalized array
Note: To save the settings in later steps for future use, please use Material test array to set up the array.
(1) Create a new project and set an element.
(2) Create a material test array.
Array specifications:
- Minimum single matrix size: 10 mm × 10 mm
- Recommended maximum rows/columns: ≤ 8
- Row/column spacing: ≥ 1 mm
(3) Ungroup the test array.
(4) Click the target grids and set parameters for all satisfied colors in the previous step, including power and speed.
(5) Click the 
icon, then choose a way to save this test array file.
(6) Click Process and take a picture of this test array on your material for later use.
3. Add material to xTool Studio
(1) Create a new project, then click Unknown material in the upper right corner.
(2) Hover over + Add Material, then click Add to Cloud or Add to Local.
(3) Input the Material name.
Note: If an official material listed below matches your material, you may click it to make it your material name.
(4) Click the + Add New button.
(5) Hover over Import parameters from file, then select Import parameters from file or From my space below to import the test array file you just saved.
(6) On the Associate Setting window, select a setting from the drop-down list, ensure that its Processing Type is set to Color Engrave, and then click Confirm.
(7) If needed, enable Set as default. Click Import to upload the picture of the processing result you took previously, then click Save.
(8) Click Apply.
Color engraving steps
1. Refer to the user guide to get the device ready, and place the material to be processed on the device.
2. Connect your F2 Ultra UV to xTool Studio.
3. Follow this to set the focus position.
Note: After laser focusing, the measured material thickness can be seen on the right side of xTool Studio.
4. Use the tools on the left side of the canvas to import or create a vector fill image or bitmap object.
5. Select the object, and use the toolbar above the canvas for further editing.
Note: If the object is a bitmap, please note the following:
(1) Select the bitmap and click Color seperation in the upper bar.
(2) Use images with solid color blocks. Avoid gradients, transitional colors, or tiny color pixels. See example:
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(3) Tiny color blocks with few pixels can be removed, as they won't noticeably affect the final piece.
6. Select an object part from the Object list, click Color Engrave in the right panel, and configure processing settings.
7. Repeat the previous step until all parts of the object have been set properly.
8. Preview the processing area.
You can use framing to preview the processing area on the material. During framing, the laser dots move along the boundary of the objects to be processed. Perform the following steps to start framing.
(1) Click ... next to Framing in the bottom-right corner of the xTool Studio window and set the framing parameters.
In Rect mode, the laser dots move along the rectangular boundary of the objects to be processed.
In Outline mode, the laser dots move along the outlines of the objects to be processed.
In Polygon mode, the laser dots move along the polygonal path defined by the vertices of the objects to be processed.
(2) Click Framing in the bottom-right corner of the xTool Studio window. The laser dots will move along the boundary of the objects to be processed, allowing you to preview their processing area on the material.
9. Click Process.
10. Click Start.
11. When the software shows Ready, press the XTOOL Start/Stop button on the touchscreen controller to start processing.
⚠️ Safety reminder: During laser processing, keep the protective enclosure closed or wear goggles that can shield laser beams of 355 ± 5 nm wavelengths.
Important notes
Processing scope
- This tutorial specifically addresses UV laser color engraving on 304 stainless steel.
- The methodology may be adapted for exploring color marking on other metals (e.g., brass, titanium).
Critical processing factors
Color inconsistency may occur even with identical parameter settings due to material inconsistencies, ambient humidity, or temperature fluctuations, which can lead to different oxide layer composition and thickness.
Explore more colors
When it comes to color engraving on 304 stainless steel, the color consistency is sensitive to equipment performance variations, ambient temperature, humidity fluctuations, material surface conditions and consistency, and more. To help obtain better colors on the material, this section outlines the rules of UV laser color engraving on 304 stainless steel, providing useful guidance for parameter adjustment when actual results deviate from target colors.
Color Spectrum Rules
As laser energy increases, colors progress through: Light yellow → Yellow → Orange → Pink → Purple → Blue-purple → Blue → Cyan → Green → Brown → Black
Parameter Adjustment Rules
Power:
0.5% increment changes one hue (follow the Spectrum Principle)
Speed:
100mm/s increment changes one hue
Frequency:
- Above 500KHz: 100-200KHz changes one hue
- Below 500KHz: Produces special dark colors (black in shadow, colored in light)
Pulse Width:
Recommended >20 ns for visible colors
<20 ns has minimal color effect
Adjustment Strategy:
4+ hue difference: Adjust power/speed
<4 hue difference: Adjust frequency/pulse width
Finish Effect Rules
Different surface finishes affect light reflection on stainless steel, leading to variations in color engraving results even with identical parameters.
304 stainless steel finish types
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Mill finish | Brushed finish | Polished finish | Mirror finish |
Color engraving results on different 304 stainless steel finishes
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On mill finish | On brushed finish (horizontal) | On brushed finish (vertical) | On polished finish | On mirror finish |
The specific rules are as follows:
- Mill &. Brushed finishes: Minimal difference in color engraving effects.
- Polished & Mirror finishes: Colors on the left side of the test array are produced as those on mill finish under the same parameters.
Warning: Please exercise extreme caution when using mirror-finished materials for color engraving processing. Due to their high reflectivity, mirror surfaces can easily cause irreversible damage to laser equipment. Particularly, do not place mirror materials in the central area for processing, and use the minimum possible power settings (usually <60).
- Energy Compensation Required:
- Polished finish: Increase power by ~1% or decrease speed by 100 mm/s to match colors on the mill finish.
- Mirror finish: Increase power by ~2% or decrease speed by 200 mm/s to match colors on the mill finish.
Note:
- Mirror finishes can be achieved via mechanical or chemical polishing. The mirror finish shown above employs the former technology.
- If your stainless steel is polished via chemical methods, the metal composition may alter, affecting color engraving outcomes.
