PETG is harder to print than PLA and easier to print than ABS. That description is accurate but incomplete. The specific challenges with PETG are predictable and fixable, and once your settings are dialed in for a specific brand and printer, PETG prints as reliably as PLA. The issues that frustrate most people switching from PLA to PETG come from trying to use PLA settings unchanged. This guide covers every setting adjustment that matters.
PETG Print Settings Reference
| Setting | PETG Value | vs PLA | Why |
|---|---|---|---|
| Nozzle temp | 235-245°C | +25-30°C | PETG needs higher temp for proper melt flow and layer bonding. Under-temp PETG delaminates. |
| Bed temp | 70-85°C | +15-25°C | Higher bed temp improves first layer adhesion and reduces warping risk. |
| Fan speed | 30-50% | Half of PLA (was 80-100%) | Critical. Aggressive cooling on PETG produces weak layer bonds. This is the #1 PETG mistake. |
| Print speed (walls) | 80-120mm/s | Slower than PLA | PETG needs more time at deposition for clean wall quality. |
| Retraction | +0.2-0.5mm vs PLA | More retraction needed | PETG strings more than PLA due to higher viscosity and temperature. More retraction helps. |
| Layer height | Same as PLA | No change | Layer height is geometry-dependent, not material-dependent. |
| Z-offset (bed gap) | Slightly higher than PLA | Less squish | PETG bonds aggressively. Too much first-layer squish can damage smooth PEI on removal. |
The Three PETG Problems and Their Fixes
Problem 1: Stringing
PETG strings more than PLA. The higher viscosity melt at higher temperatures oozes more on travel moves.
Fix sequence: Increase retraction 0.2-0.3mm above your PLA value. Increase travel speed to 200mm/s+ to minimize time the nozzle spends oozing during travel. Enable combing (travel over solid geometry rather than open air where possible). If stringing persists, reduce temperature 5°C.
Problem 2: PETG Sticking Too Hard to the Bed
PETG bonds aggressively to smooth PEI at printing temperatures and can tear the PEI coating when the print is removed.
Fix: Apply a thin layer of glue stick (Elmer’s purple washable) to smooth PEI before printing PETG. The glue acts as a release agent. The print bonds to the glue rather than directly to the PEI surface, releasing cleanly when cooled. Textured PEI is more forgiving and releases PETG without a glue stick in most cases.
Problem 3: Layer Separation
The most common PETG-specific failure. Lines between layers are visible, parts delaminate under light pressure, or the outer wall peels away from infill.
Cause: Fan speed too high. PETG needs time for inter-layer molecular bonding and aggressive cooling prevents this. Fan at 100% (PLA setting) on PETG is almost always too high.
Fix: Reduce fan to 30-50%. This single change fixes the majority of PETG layer separation. Also ensure temperature is at the upper end of the PETG range (240-245°C). Under-temperature PETG has weaker layer bonds regardless of fan setting.
PETG Surface Quality: Expectations vs Reality
PETG produces slightly shinier surfaces than PLA due to its translucency and surface flow characteristics. This looks good unpainted. It also means PETG shows imperfections like blobs and layer irregularities more visibly than matte PLA.
For painted PETG: Score the surface lightly with 220-grit sandpaper before priming. PETG’s slight translucency and smooth surface resists primer adhesion. A quick scuff creates mechanical texture for primer to grip. Alternatively use a plastic adhesion primer (Rust-Oleum Adhesion Primer) which chemically bonds to the PETG surface.
Elephant’s foot on PETG: More pronounced than PLA because PETG is slightly softer at bed temperature and spreads more. Raise z-offset slightly (0.05mm) compared to your PLA z-offset and reduce bed temperature toward the lower end of the PETG range (70°C).
PETG in Florida: Storage and Printing Environment
PETG absorbs moisture at a moderate rate. In South Florida’s humidity, an open PETG spool degrades noticeably in 3-7 days. Wet PETG produces increased stringing, rough surfaces, and reduced layer adhesion. Store sealed with desiccant at all times.
PETG’s 75°C heat deflection temperature makes it the right choice for any print that will be transported in a Florida car in summer, worn at outdoor conventions, or stored in a garage. See the PETG vs PLA comparison for the full material trade-off analysis.