PETG prints like PLA’s cranky older sibling. It’s tougher, more heat-resistant, and doesn’t snap — but it strings like spider silk and either bonds permanently to your bed or refuses to stick at all. After running hundreds of PETG spools through everything from Ender 3s to Vorons, I’ve dialed in settings that eliminate the frustration. Here’s the exact profile.
How to Print PETG Without Stringing or Adhesion Headaches
Step 1: Get First Layer Adhesion Right — The PETG Paradox
PETG adhesion is bipolar. On bare glass, it bonds so aggressively it can rip chunks out of the surface when you remove the print. On untreated PEI, it sometimes won’t stick at all. The fix is a release agent that also promotes adhesion — sounds contradictory, but it works.
Best bed surfaces for PETG, ranked:
- Textured PEI sheet — Gives excellent adhesion hot (80-85°C) and self-releases when cool. No glue stick needed. This is the gold standard.
- Smooth PEI with glue stick — The glue stick acts as a release agent, not an adhesive. Spread a thin, even layer. Without it, PETG can fuse to smooth PEI and tear the coating.
- Glass with glue stick or hairspray — Works reliably but requires reapplication every 2-3 prints.
- Bare glass — Never. PETG bonds covalently to bare glass. You will chip the glass removing the print.
Z-offset adjustment: PETG needs slightly more gap than PLA — about 0.05-0.10 mm higher. PLA likes squish; PETG does not. If the first layer looks smeared and translucent, the nozzle is too close. Back off until the extruded line has a slightly rounded top profile with visible layer lines.
Bed temperature: 80°C for the first layer, 75-80°C for subsequent layers. Below 70°C and PETG warps on prints wider than about 100 mm. Above 85°C and the print base stays too soft — you get elephant’s foot on the first 2-3 layers.
Step 2: Dial In Extrusion Temperature
PETG prints between 230-250°C depending on brand and print speed. Start at 240°C and run a temperature tower (225-255°C in 5°C increments) for each new spool. Different colors — even from the same brand — print at different optimal temperatures. White PETG often needs 5-10°C more than black because the titanium dioxide pigment affects melt flow.
Signs of too cold: Matte finish, poor layer adhesion (the print delaminates with hand pressure), extruder clicking.
Signs of too hot: Glossy finish with excessive stringing, sagging on overhangs, burnt wisps of filament accumulating on the nozzle.
Step 3: Eliminate Stringing — The PETG Nemesis
PETG’s stringing comes from its high melt viscosity and long molten tail. It doesn’t snap clean like PLA. Four settings control it:
Retraction distance: 4-6 mm for Bowden, 1-2 mm for direct drive. Too much retraction pulls molten PETG into the cold zone, causing heat creep clogs. Too little and strings connect every travel move.
Retraction speed: 25-40 mm/s. Faster isn’t better — above 50 mm/s, the extruder gear can strip the filament instead of pulling it back.
Travel speed: 150-200 mm/s on travels. The faster the nozzle moves between extrusion points, the less time the oozing filament has to form a string. This is the single most effective anti-stringing setting for PETG — crank it as high as your printer’s mechanics allow without layer shifting.
Wipe and coast: Enable “Wipe while retracting” (0.4-0.8 mm) and set coasting volume to 0.064 mm³ (default Cura value). Coasting stops extrusion slightly before the end of a line, letting the built-up nozzle pressure empty naturally instead of oozing on the travel move.
Avoid crossing perimeters: Enable “Avoid printed parts when traveling” and “Avoid supports when traveling.” This forces travel moves to stay within the infill, where any strings are invisible.
Step 4: Fan Speed Management
PETG layer adhesion weakens dramatically with too much cooling. The polymer chains need time to entangle before solidifying.
Perimeters and solid infill: 20-40% fan after layer 3. This provides enough cooling for overhang definition without killing layer adhesion.
Bridging: 100% fan only during bridges. The fan auto-modulation in modern slicers handles this — set bridge fan speed to 100%, regular fan to 30%.
First 3 layers: 0% fan. This ensures strong bed adhesion and prevents warping on large footprints.
Enclosure: PETG doesn’t need an enclosure for small prints, but anything over about 150 mm in any dimension benefits from a draft shield or partial enclosure. Room drafts cause uneven cooling, which creates warping forces that pull corners off the bed. A cardboard box over the printer during the first 10 layers is a zero-cost enclosure that works.
PETG Print Settings Reference Table
| Setting | Recommended Value (Bowden) | Recommended Value (Direct Drive) | Effect if Too High | Effect if Too Low |
|---|---|---|---|---|
| Nozzle Temperature | 235-245°C | 230-240°C | Excessive stringing, burnt blobs | Poor layer adhesion, matte finish |
| Bed Temperature | 75-80°C | 75-80°C | Elephant’s foot, soft base | Warping, corner lift |
| Retraction Distance | 4-6 mm | 1-2 mm | Heat creep, filament grinding | Stringing, wisps on travel moves |
| Retraction Speed | 25-35 mm/s | 30-40 mm/s | Stripped filament, extruder skip | Ineffective retraction |
| Travel Speed | 150-200 mm/s | 150-250 mm/s | Layer shifting (mechanical limit) | Stringing (nozzle dwells) |
| Part Cooling Fan | 20-40% (after layer 3) | 20-40% (after layer 3) | Brittle parts, delamination | Sagging overhangs |
| First Layer Speed | 15-25 mm/s | 20-30 mm/s | Poor adhesion, lifted corners | Elephant’s foot from dwell time |
| Z-Offset (vs PLA) | +0.05-0.10 mm | +0.05-0.10 mm | No adhesion, spaghetti | Nozzle digging, smeared first layer |
PETG Printing Mistakes
Mistake 1: Using PLA retraction settings for PETG
PETG oozes more than PLA during travel because it has a wider melt transition. Copying your PLA profile’s 2 mm retraction to PETG guarantees stringing. Start 1-2 mm higher for Bowden, 0.5-1 mm higher for direct drive.
Mistake 2: Printing PETG on bare glass or smooth PEI without a release agent
PETG contains glycol-modified PET, which chemically bonds to silicates in glass and adhesives on PEI. The bond can exceed the cohesive strength of the bed surface — the print tears the surface coating off. Always use a release layer (glue stick, hairspray, or Magigoo) on smooth surfaces. Textured PEI is the exception — the texture provides microscopic air gaps that break the vacuum effect.
Mistake 3: Storing PETG without drying, then printing it wet
PETG is hygroscopic — it absorbs moisture from ambient air within 48-72 hours. Wet PETG pops and sizzles at the nozzle (you can hear it), creates surface bubbles, and strings 3x worse than dry filament. Dry at 65°C for 4-6 hours before the first print and store in a sealed container with desiccant. This alone fixes more “PETG problems” than any slicer setting.
Mistake 4: Not reducing flow rate for PETG
PETG is denser than PLA and melts more completely in the hotend. At 100% flow rate, most PETG over-extrudes by 3-8%. Reduce flow to 95-97% and calibrate with a single-wall cube (measure wall thickness, should match nozzle diameter × 1.0, not 1.05+). Over-extruded PETG builds up on the nozzle, creating blobs that eventually drop onto the print.
⚠️ Safety Notice: PETG printing at 230-250°C releases low levels of volatile organic compounds (VOCs) including caprolactam and styrene derivatives. Print in a well-ventilated area or use an enclosure with a fume extraction system. The printer’s electrical components must be rated for the continuous current draw at these temperatures. Fire safety requires a smoke detector near the printer and a fire extinguisher rated for electrical fires.
As we covered in our PLA vs PETG comparison, the material choice depends heavily on your application. For PETG parts that need reliable bed adhesion on large prints, review our 3D Printer Bed Adhesion Fixes guide.
For FPV pilots printing TPU camera mounts and PETG frame parts, eSUN PETG offers the best balance of printability and impact resistance — it strings less than budget brands and holds layer adhesion down to 235°C. Available in the filaments section at uavmodel.com.