Gradient Effect prints a uniform mixed color instead of a height-based gradient

[i-skachkov]

Type of issue

Other (functional bug, wrong result, UI glitch, etc.)

Bambu Studio Version

2.7.1.62 as well as bet

Where is the application from?

Bambu Lab Official website

OS version

Windows 11 and Mac OS

Additional system information

Windows 11
Имя устройства P3PGQEL
Процессор Intel(R) Core(TM) Ultra 9 185H (2.50 GHz)
Оперативная память 32,0 ГБ (доступно: 31,4 ГБ)
Код устройства 19C3BED1-8E8B-487D-9463-0DA7ABDF1FF4
Код продукта 00329-10021-99067-AA968
Тип системы 64-разрядная операционная система, процессор x64
Перо и сенсорный ввод Для этого монитора недоступен ввод с помощью пера и сенсорный ввод

Mac
M1 16 GB 512 GB

Printer

Bambulab X2D

How to reproduce

Reproduction steps

1. Add a Mixed Filament profile from two PLA Silk+ filaments.
2. Enable Gradient Effect.
3. Configure the curve from 100% material 1 at the bottom to 100% material 2 at the top.
4. Assign this mixed filament profile to a model.
5. Slice and print.
6. Observe that the color mixture remains visually uniform from bottom to top.
   Description
   The Color Mixing → Gradient Effect does not produce the expected color transition along the model height.
   I created a mixed filament profile using:

• Filament 1: Bambu PLA Silk+ Green
• Filament 2: Bambu PLA Silk+ Gold
• Gradient Effect: enabled
• Direction: Filament 1 → Filament 2
• Enable per-part gradient effect: disabled
  The configured curve is:
• Green at 100% for the lower ~25–30% of the model
• Gradual transition from green to gold through the middle section
• Gold at 100% near the top
  Printer and materials
• Printer: Bambu Lab X2D
• Materials: two Bambu PLA Silk+ filaments, green and gold
• AMS: [please add model/configuration]
• Nozzle: [please add]
• Layer height: [please add]
• Bambu Studio version: [please add]
• Printer firmware version: [please add]

Actual results

The finished print has the same apparent green/gold mix across its entire height. The print appears to use a constant alternating-layer pattern rather than changing the proportion of the two filaments according to the gradient curve.

Expected results

The lower part of the model should print fully green, the upper part fully gold, with a gradual transition in between.
Actual behavior

File uploads (project / log / crash dump / performance profile)

bambu-studio.zip

Checklist of files to include

• Project file (always)
• Log file (always)
• Crash dump / report — required for crash / freeze issues (Windows .dmp / macOS .ips / Linux gdb backtrace)
• Performance profile — required for performance / lag issues

[BambulabRobot]

Hi, thank you for taking the time to report this issue and for the details you've already provided — they are very helpful!

To help us pinpoint the root cause more accurately, it would be great if you could also share:

• Thank you for the detailed reproduction steps and system information! To help us investigate the gradient effect behavior, could you please upload the 3MF project file that reproduces this issue? This will allow us to inspect the exact gradient curve configuration and slice settings. You can export it via File → Save Project As in Bambu Studio.

Of course, if you have any other context (screenshots, screen recordings, software version, OS info, etc.),feel free to add them as well. We appreciate your help and patience!

[SSSmAsHeRRR]

I can confirm the same issue on Bambu Studio 2.8.2.60 on macOS with a Bambu Lab H2D.

When using Gradient Effect with two filaments, the gradient is not visually shown on the model, and after slicing, the Preview appears to alternate the two filaments in a fairly regular pattern instead of progressively changing their proportion with Z height.

The gradient curve therefore seems to be ignored, producing a constant color mix instead of a real vertical gradient.

[Gildashard]

Same issue on 2.8.2.60 on Windows 11 on H2C. Looking at the Preview, the filament use should show far less red than blue but its roughly equal.

Mixed filament gradient issue.zip

[Lorn888]

Same issue

[mvanhorn]

Implemented in #12008.

[logikal]

same issue. you can see that the object is uniformly mixed, no matter what height curve is chosen.

This is in osx bambu studio 2.8.2.61.

attached another 3mf for you @BambulabRobot . Would be great if you could get this assigned or merge OP's PR for the next release.

3DBenchy-color-mixing-bug.3mf.zip