PETG is harder to print than PLA but more useful — it handles 80°C without deforming, bonds well between layers, and tolerates moisture and mild chemicals that would degrade PLA within weeks. The main annoyances: it strings more than PLA, it sticks so aggressively that it can pull chunks off a glass bed, and wet spools produce prints that look fine but snap unexpectedly.
Where PETG Makes Sense
Mechanical parts exposed to moderate heat (electronics enclosures, printer parts), containers for liquids or cleaning products, outdoor applications in temperate climates, anything that needs to survive a dishwasher cycle on the bottom rack.
Where PETG Underperforms
High-heat environments above 75°C — use ASA or ABS instead. Parts requiring tight dimensional tolerances — PETG shrinks inconsistently across brands. Anything requiring a hard, smooth surface finish without post-processing.
Temperature Starting Points
Nozzle: Start at 235°C. Most PETG brands print cleanly in the 230–245°C range. Going above 245°C dramatically increases stringing without benefit. If you’re fighting stringing, drop temperature before touching retraction.
Bed: 75–80°C on PEI. On glass, 80–85°C is more reliable. Let the bed soak for 5 minutes after reaching temperature — PETG adhesion is sensitive to the bed surface being fully at temperature, not just the sensor reading.
The First Layer Problem
PETG bonds to surfaces more aggressively than PLA. On bare glass or PEI, it can fuse permanently. Solutions: apply a thin layer of PVA glue stick as a release agent, use a textured PEI surface (not smooth), or reduce first layer squish — the Z-offset for PETG should be slightly higher than PLA, not lower.
If the first layer rips the PEI coating when removed, your Z-offset is too low or your bed temperature is too high. Drop bed to 70°C and don’t let the part cool below 30°C before removal.
Retraction
PETG requires more retraction than PLA due to higher melt viscosity and adhesion. Start at 1.0mm (direct drive) or 5mm (Bowden), and increase by 0.5mm increments. Don’t exceed 2mm on direct drive — this causes consistent jams in the heatbreak.
Fan Speed
40–60% is the target range. PETG needs some cooling for overhangs but too much cooling hurts layer adhesion. 100% fan produces brittle inter-layer bonding on load-bearing parts. Full fan is only appropriate for detailed models where strength isn’t critical.
Moisture Sensitivity
PETG absorbs moisture noticeably within 24–48 hours of open air exposure in humid climates. Signs of wet PETG: audible popping during extrusion, rough surface texture, more stringing than usual, and prints that snap cleanly along layer lines. Dry at 65°C for 4–6 hours. Keep open spools in sealed containers with desiccant if you’re not printing daily.