PETG settings: temperature, cooling and stringing fixes
PETG prints best at 225–245 °C on a 70–85 °C bed, with the part fan at 30–50% and no enclosure. It's tougher than PLA and handles heat up to roughly 70 °C. It also strings more and can weld itself to smooth PEI, so dry the spool and print on textured PEI or a glue-stick release layer.
- Nozzle 225–245 °C. Start at 235 °C. Fast printers and PETG-HF often run 240–260 °C.
- Bed 70–85 °C on textured PEI, or smooth PEI with a thin coat of glue stick.
- Part fan 30–50%, off for the first 2–3 layers.
- Don't over-squish the first layer. Raise the Z-offset slightly compared with PLA.
- Dry it at 60–70 °C for 4–6 hours if it strings or pops.
PETG print settings table
Starting values for Bambu Lab, Prusa, Creality and other FDM printers. Your spool's label wins if it disagrees: Prusament PETG, for example, is rated 250 ± 10 °C.
| Setting | Starting value | Notes |
|---|---|---|
| Nozzle temperature | 225–245 °C | Start at 235. Cooler cuts stringing; hotter gives stronger layers. |
| High-speed / PETG-HF | 240–260 °C | Faster flow needs more heat. Bambu rates its PETG HF at 230–260 °C. |
| Bed temperature | 70–85 °C | 75–80 is a good default. Go to the top of the range for big parts. |
| Part cooling fan | 30–50% | Off for the first layers. More fan cleans up overhangs but weakens layers. |
| Enclosure | Not needed | Avoid cold drafts. On enclosed printers, crack the door if the chamber runs warm. |
| Print speed | 40–80 mm/s (standard hotend) | PETG-HF on a high-flow hotend can go much faster. Flow is the limit. |
| Max volumetric flow | About 8–12 mm³/s (standard) | Lower than PLA on the same hotend. HF grades are made to flow faster; use the vendor profile. |
| Retraction | 1–3 mm direct drive; 4–7 mm Bowden | 25–40 mm/s. Tune with a retraction test, in small steps. |
| First-layer Z-offset | Slightly higher than PLA | Squished PETG piles up on the nozzle and drops blobs. |
| Layer height | 0.12–0.28 mm (0.4 mm nozzle) | 0.20 mm is the everyday default. |
| Bed surface | Textured PEI; smooth PEI only with glue stick | The glue is a release layer, not an adhesive. |
| Drying | 60–70 °C, 4–6 h | Up to 8 h for soaked, translucent or HF spools. |
How to stop PETG stringing
PETG is sticky when molten, so a few wisps are normal. A spider web is not. Work through these in order; each one is cheaper than the next.
- Dry the filament. Wet PETG strings no matter what else you change. 60–70 °C for 4–6 hours.
- Lower the nozzle 5 °C at a time until the surface dulls or layers weaken, then go back up 5.
- Tune retraction with a retraction test. Change distance in 0.2–0.5 mm steps.
- Turn on wipe while retracting so the nozzle drags the ooze onto the part.
- Keep travel inside the part ("avoid crossing walls" or combing) and use fast travel moves.
- Clean the nozzle. PETG residue on the tip turns into blobs and burnt specks.
Leftover hairs come off with a quick pass of a heat gun. For the full list of causes, see stringing and oozing.
PETG sticking too well to PEI
PETG grips smooth PEI so hard that pulling the print off can tear the coating. Prusa tells users not to print PETG on smooth PEI at all unless they add glue stick first.
- Use a textured (powder-coated) or satin PEI sheet. The texture grips mechanically and releases when cool.
- On smooth PEI or glass, wipe on a thin layer of glue stick as a release layer.
- Raise the Z-offset slightly. PETG doesn't need the squish PLA does.
- Let the bed cool fully, then flex the sheet. Never pry a hot PETG print off PEI.
Your PETG print ripped a chunk out of your smooth PEI sheet. What's the best fix for next time?
PETG bonds chemically to smooth PEI. Textured PEI or a thin glue-stick layer gives it something to release from. A hotter bed or more squish makes the bond even stronger.
PETG temperature resistance
PETG's glass transition is about 80 °C, and data-sheet HDT values (0.45 MPa) run 68–78 °C: 68 °C for Prusament PETG, 69 °C for Bambu PETG HF and 78 °C for Polymaker PolyLite PETG. Prusa rates PETG parts for use below 80 °C.
In practice that covers most indoor and outdoor parts, warm electronics enclosures and garden hardware. A parked car's dashboard in summer is borderline; use ASA or ABS there. PETG also holds up outdoors much better than PLA, though ASA is the specialist for years of direct sun.
PETG-HF, PETG-CF and other PETG types
| Type | Best for | How to print it | Watch out for |
|---|---|---|---|
| Standard PETG | Brackets, enclosures, outdoor parts | 225–245 °C | Stringing; PEI over-adhesion |
| PETG-HF / high-speed PETG | Fast CoreXY printers | About 230–260 °C with a high-flow profile | More moisture-sensitive; Bambu lists drying as required |
| PETG-CF (carbon fiber) | Stiff, matte functional parts | 240–270 °C, hardened steel nozzle | Abrasive; slightly better heat resistance (Bambu PETG-CF: 74 °C HDT) |
| Translucent PETG | Lamp shades, light pipes | Standard settings, very dry filament | Moisture shows up as cloudiness and bubbles |
| PET-CF (not PETG) | Engineering parts near 200 °C | 260–300 °C, enclosure, hardened nozzle | See the engineering filaments guide |
PETG troubleshooting: common problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Stringing and wisps | Wet filament or nozzle too hot | Dry the spool, lower 5 °C at a time, turn on wipe. |
| Blobs and burnt specks on the print | Residue building up on the nozzle | Raise the Z-offset slightly, clean the nozzle, fit a silicone sock. See blobs and zits. |
| Torn PEI sheet | Chemical bond to smooth PEI | Textured PEI or glue stick; remove only when cool. |
| Ridges or nozzle dragging on layer one | Z-offset too low | Raise it 0.02–0.05 mm. |
| Weak layers that split | Too much fan or too cold | Fan to 30%, nozzle up 5–10 °C. |
| Droopy overhangs, saggy bridges | Not enough cooling | Bridge and overhang fan 80–100%, slow those features. |
| Popping, bubbles, cloudy surface | Wet filament | Dry at 60–70 °C for 4–6 hours. |
| Corners lifting on big parts | Drafts or cool bed | Bed to 80–85 °C, add a brim, block drafts. |
| Clogs on an enclosed printer | Heat creep from a warm chamber | Open the door; check the hotend fan. |
Is PETG food safe?
Not automatically. PET-family plastics are common in food packaging, and Prusa notes PETG itself may be considered food-safe. But it still doesn't recommend any printed part for direct food contact, because layer lines harbor bacteria. Colorants and brass nozzles add more unknowns.
If you print food-contact parts anyway: pick a spool with a food-contact declaration for that color, use a clean stainless-steel nozzle, seal the surface with a food-safe coating, and treat the part as single-use. Hot dishwashers can soften PETG near its 70–80 °C limit.
PETG vs PLA vs ABS: when to choose PETG
| Material | Nozzle | Bed | Heat resistance (HDT) | Main strength |
|---|---|---|---|---|
| PLA | 200–220 °C | 55–65 °C | About 55–60 °C | Easy, stiff, detailed |
| PETG | 225–245 °C | 70–85 °C | About 68–78 °C | Tough, low warp, water resistant |
| ABS / ASA | 235–260 °C | 95–110 °C | About 87–103 °C | Heat resistance; ASA resists UV |
Choose PETG for brackets, snap-fit enclosures, planters, outdoor fixtures, printer parts and anything PLA would crack or soften.
Skip PETG for fine miniatures (the PLA guide is your friend), parts that live in hot cars, and anything that must be acetone-smoothed (see the ABS and ASA guide).
Frequently asked questions
What is the best temperature for PETG?
Start at 235 °C and stay within 225–245 °C on a 70–85 °C bed. High-speed printers and PETG-HF filaments often need 240–260 °C to melt fast enough.
Why is my PETG stringing?
PETG strings mostly because it is wet or too hot. Dry it at 60–70 °C for 4–6 hours, lower the nozzle 5 °C at a time, then fine-tune retraction and turn on wipe.
Does PETG need an enclosure?
No. PETG barely warps and prints well on open printers. Keep cold drafts away, and on an enclosed printer open the door if the chamber gets warm enough to cause clogs.
Is PETG stronger than PLA?
PETG is tougher: it bends instead of snapping and handles heat to roughly 70 °C, versus 55–60 °C for PLA. PLA is stiffer and prints sharper detail.
Is PETG food safe?
Not automatically. PETG resin is widely used in food packaging, but printed layer lines trap bacteria, and nozzles or colorants can add contaminants. Use a food-contact-declared spool, a stainless-steel nozzle and a food-safe coating, and treat parts as single-use.
Related articles
Sources & further reading
- Prusa Knowledge Base: PETG material guide
- Prusament: Prusament PETG technical data sheet
- Bambu Lab Wiki: Filament guide (nozzles, temperatures, drying)
- Prusa Knowledge Base: Drying filament
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