PETG problems: stringing, sticking, blobs, weak layers

This guide is for PETG prints that string, rip the surface off a build plate, won't stick, leave blobs, or split between layers. It collects what Bambu Lab, Prusa, Polymaker, Overture, eSUN, ELEGOO and Creality say about their own PETG, and keeps each setting to the product or printer the maker names. Our other guides go deeper on each general problem, so this page sticks to what's specific to PETG and links out for the rest. Start here:

What temperatures do PETG makers give?

Prusa and Overture both point back to the profile before anything else. The makers' own ranges vary:

Bambu's general filament guide lists plain "PETG" at 240–270 °C and PETG HF at 230–260 °C, while the PETG Basic data sheet says 230–260 °C, so check the data sheet for the exact Bambu product you have. Prusa says "we suggest using the PrusaSlicer profiles that should work fine," and Overture's FAQ says a mismatch between Bambu Studio's Generic PETG-HF profile and Overture PETG can cause poor bed adhesion, stringing, weak layer bonding and under-extrusion. Overture puts that down to "incorrect temperature and cooling balance."

Stringing and oozing

Every maker here names moisture or temperature, or both:

• Prusa calls PETG "prone to stringing" and says "stringing can be moderated with higher retractions and lower nozzle temperature." It also says cooling the print helps prevent stringing and oozing.
• Polymaker says "dry the filament first. If stringing remains, reduce the nozzle temperature within the recommended 240–260°C range, then fine-tune retraction and travel settings."
• Overture says PETG stringing "is usually caused by moisture in the filament or improper settings," and to always dry the filament before use.
• eSUN says "to prevent stringing, oozing, and nozzle buildup, PETG should be dried at 60°C for 8 hours."
• Creality says PETG's "moisture absorption can cause stringing issues with prints," and recommends its dryer for drying and storing PETG.
• Bambu Lab says the reformulated PETG Basic "shows reduced stringing thanks to its lower sensitivity to moisture compared to typical PETG filaments," but adds that drying is still recommended.

Three makers publish retraction starting points for their own PETG:

eSUN's PETG data sheet suggests turning on Z seam alignment, turning off "Z-axis lift," avoiding travel through the outer shell, and reducing print speed "to achieve the best printing effect." Prusa says that if a tiny bit of stringing is left on Prusament PETG, you can remove it "by quickly blasting your finished prints with a heat gun."

Our stringing guide covers temperature towers, retraction tests and travel settings for any material.

Sticking too hard: smooth PEI and release layers

PETG grips some plates so hard that taking the print off damages the plate. Five makers address it below, Prusa on both its help site and its Prusament page.

Prusa's surface preparation guide calls PETG on a clean, degreased smooth PEI sheet its "most common" example, and recommends "using another type of steel sheet or adding PVA glue as a separation layer."

Textured plates still need care. Bambu says PETG Basic "adheres strongly to the PEI plate," so wait for the plate to cool before removing the model "to avoid damaging the bottom surface." Polymaker's FAQ says that on textured PEI, "you need to let the print and bed sheet cool to room temp before removing," and to use a bed separation agent if needed.

On Bambu printers, the Cool Plate is marked "Not recommended" for PETG in Bambu's filament guide, while the Cool Plate SuperTack is "designed only for printing PLA and PETG."

Our print stuck to the bed guide covers how to free a stuck PETG print without damaging the plate, and our PEI sheet damage guide covers what to do once a sheet is torn.

First layer and Z offset

Prusa: squish PETG slightly more

Prusa's Live adjust Z article says "PETG and other high-temperature materials require to be squished in the surface slightly more as they tend to warp (lift up), compared to the PLA." Its warping article says to lower Live Adjust Z slightly to increase bed adhesion, "but not too much," and warns that "the bed adhesion might be too high with PETG or PC and might result in a damaged PEI surface."

Prusa gives both pieces of advice: a slightly more squished first layer for PETG, and glue stick as a separation layer if you print it on a smooth PEI sheet.

What else the makers suggest

• Polymaker: "If the first layer is not sticking, slightly increase the bed temperature and slow down the first-layer printing speed."
• Overture: use glass or PEI, possibly with a light adhesive like glue stick or hairspray, calibrate the first layer height, print the first layers slower, and "reduce or turn off the cooling fan during the first few layers." It also says to "check that the nozzle height is not too high."
• Bambu Lab: its warping guide says "first layer must be squished," and suggests setting "No cooling for first X layers" to 3 if the first layer won't stick.
• Prusa: print "the first few layers with the print fan off to prevent deformation."

For first-layer checks that apply to any material, see our first-layer adhesion guide, and for corners that lift, our warping guide. If the base of the part flares out, see our elephant's foot guide.

Blobs and nozzle buildup

Bambu Lab says noticeable buildup on the outside of the nozzle "happens mostly with PETG-type filaments, including standard PETG and PETG-CF." It names damp filament as "one of the most common causes," then a flow ratio set too high, a speed and temperature mismatch, a faulty nozzle wiper, and models with many travel moves. Its numbers for PETG-type filaments:

• Flow ratio: 0.93 to 0.96. Below 0.93, gaps and weaker layer bonding become more likely. Above 0.96, oozing and buildup become more likely. Bambu PETG Basic and PETG-CF default to 0.95.
• At low speeds: lower the nozzle temperature by 5–10 ℃, lower the max volumetric speed by 4–5 mm³/s, and raise the max fan speed threshold by 10–20%.
• Many travel moves: retraction of 1.2 to 1.6 mm at 40 to 60 mm/s, and "as a rule, keep it under 2 mm."

eSUN also lists nozzle buildup among the problems drying prevents. ELEGOO says its PETG HF "can reach up to 600 mm/s, while moderate speed settings are recommended for the most consistent print quality."

Our filament sticking to the nozzle guide covers Bambu's full steps and how each printer maker says to clean a blob off safely. For blobs and zits on the part's surface, see our blobs and zits guide.

Why are PETG layers weak?

Polymaker gives a direct fix for its PETG: "Reduce cooling within the recommended 20–60% range, slightly increase the nozzle temperature within the recommended range, and reduce printing speed if needed. If using an enclosed printer, closing the enclosure may also help improve layer adhesion." Its FAQ sets the fan at a minimum of 20% "at 30 second layer time" and a maximum of 60% "with 10 second layer time."

Prusa and Overture describe the same trade-off between cooling and strength:

• Prusa: "if you want the model to be as tough as possible, try to turn off the print fan. Higher filament temperature improves merging between layers which leads to better mechanical resistance." For solid parts, it says to increase the number of perimeters "instead of adding more infill."
• Overture: the fan improves the surface by reducing stringing, "but be aware that it may weaken layer adhesion. Conversely, not using a fan can enhance layer adhesion and strength."
• Bambu Lab: a flow ratio below 0.93 makes it more likely that "layers bond together more weakly."

Our layer adhesion guide covers the general checks for temperature, cooling, drafts and moisture.

Drying

The makers agree PETG takes on moisture, but not on how hard to dry it.

Polymaker's own product page also shows 65 °C for 4 h in its specification block, and Bambu's general tables give generic PETG 60–65 °C (drying guide) and 70 °C (filament guide) for 8 h in a forced-air oven. Use the figure for your exact spool, and the data sheet where there is one.

Bambu says "do not use a microwave oven or a kitchen oven to dry filaments," because the heat is uneven. Its AMS 2 Pro and AMS HT lower the drying temperature to 55 °C once you start printing with PETG. Our wet filament guide covers how to tell if a spool is damp.

Bridges, overhangs and supports

Prusa lists "Poor bridging and overhangs" and "Supports are hard to remove" among PETG's cons, and Prusament's page adds "Not suitable for tiny parts." What the data sheets give:

• Bambu Lab PETG Basic and PETG HF: maximum overhang angle about 70°, maximum bridging length about 30 mm. Support material is "Support for PLA/PETG" for PETG Basic and "Support for PETG" for PETG HF.
• Overture PETG: threshold overhang angle 60°, and a raft separation distance of 0.1–0.2 mm.

See our overhangs and bridging guide and our supports hard to remove guide for the general settings. If the supports come out welded into one piece with the part, see our supports fused to the part guide.

A sensible order

1. Load the filament maker's profile or settings, not a generic or PLA profile.
2. Dry the spool to its maker's setting, and keep it sealed with desiccant.
3. For stringing, lower the nozzle temperature within the maker's range, then tune retraction from the maker's numbers.
4. On smooth PEI, use glue as a release layer, or switch to a textured or satin plate. Let the plate cool before removing the part.
5. If the first layer won't stick, lower the Z offset slightly (Prusa) or slow the first layer and raise the bed slightly (Polymaker).
6. For nozzle buildup on a Bambu printer, keep the flow ratio between 0.93 and 0.96.
7. For weak layers, reduce cooling within the maker's range, raise the temperature slightly and slow down.
8. On an enclosed Bambu printer, follow Bambu's door and top-cover rule for your bed temperature.

Checklist

• Nozzle, bed and fan inside the filament maker's ranges.
• Filament dried to its maker's setting, not past it (Overture warns about brittleness).
• Glue or another release layer on smooth PEI, or a textured or satin plate instead.
• Plate cooled before the part comes off.
• First layer squished slightly more than for PLA on Prusa printers.
• Flow ratio 0.93 to 0.96 on Bambu printers.
• Retraction set from the maker's numbers, and under 2 mm on Bambu printers.
• Cooling reduced for parts that need strength.
• No Cool Plate for PETG on Bambu printers (the Cool Plate SuperTack is fine).

If you're still choosing a spool, our PETG shortlist compares the spools themselves.

How this guide was checked

This is a research-based guide. We haven't run these tests for it. Every setting, quote and recommendation comes from the Bambu Lab, Prusa Research, Prusa Polymers, Polymaker, Overture, eSUN, ELEGOO and Creality pages and data sheets listed in the sources, retrieved on 2026-10-13. Settings are kept to the product or printer each page names, and where makers disagree we show both. Bambu's store page says PETG HF "is discontinued and will not be restocked once sold out," so its settings are here for existing spools. Read more in our editorial standards.

PETG: what to check before you buy a spool ↗