PLA supports for PETG, and PETG supports for PLA
Use a different filament only at the support contact surface, with a small separation and strength test before a full print.
Assign the contact material
PLA and PETG often separate more easily from each other than from themselves. Keep the support body in the model material and assign the other filament only to the interface. Preview every swap: some support styles can create unexpected material changes.
Start with a source, then test the pair
One published PLA/PETG experiment used zero contact Z distance, zero interface spacing and one interface layer. Another X1 Carbon owner reported clean separation using a 0.20 mm preset with Bambu Tough PLA and PETG Basic. These are different experiments, not a combined verified profile.
Protect the model from contamination
On a shared nozzle, tune flushing in both directions and keep interface waste out of structural infill. A color-clean purge does not prove polymer purity. On separate nozzles, validate priming, ooze and nozzle-specific material support. Test strength across the heights where material swaps occur.
Check the hardware first
The machine must support the required material changes within a layer. A simple layer pause on a single-material machine usually cannot do this job. Dedicated support products have specific compatibility lists; soluble support is not automatically suitable for every material or feeder.
Sources & further reading
This is our troubleshooting sequence, informed by the sources below. Community outcomes belong to their authors and have not been independently reproduced.