Filament Guide
PETG Filament Guide
The practical workhorse. Tougher and more durable than PLA.
Last updated: March 2026
PETG
Polyethylene Terephthalate Glycol-modified
The practical workhorse. Tougher and more durable than PLA.
Beginner-Intermediate
Very Popular
PETG is a modified form of PET - the same plastic used in water bottles - with glycol added during polymerisation to prevent the crystallisation that makes standard PET brittle and hard to print. The result is a semi-crystalline thermoplastic that combines decent toughness, chemical resistance, and heat resistance while remaining easier to print than ABS or Nylon.
PETG was adopted into FDM printing in the early 2010s and has become the second most popular filament after PLA. It sits in a sweet spot: meaningfully stronger and more temperature-resistant than PLA, but without the warping headaches of ABS.
Its main quirk is stringing - PETG is "sticky" and oozes more than PLA, requiring careful retraction tuning. It's also slightly flexible, which can be a pro or con depending on the application.
Chemistry
Polyester - PET modified with glycol comonomer to suppress crystallisation
Print Temp
Heat Resistance
Softens at ~80°C[2] - survives car interiors on most days
Food Safe?
Base material is, but layer lines harbor bacteria. Not safe without coating.
Chemical Resistance
Good vs. water, weak acids. Attacked by ketones and strong solvents.[1]
UV Resistance
Better than PLA, worse than ASA. Degrades over years of outdoor exposure.
Pros
- Much tougher and more impact-resistant than PLA
- Good heat resistance for everyday use (~80°C)
- Very little warping - no enclosure needed
- Slight flexibility adds durability
- Good layer adhesion and interlayer strength
- Decent chemical resistance
- Transparent/translucent variants print beautifully
Cons
- Strings aggressively - retraction tuning required
- Sticks too well to PEI/glass if overheated
- Softer surface - scratches more easily than PLA
- Absorbs moisture - needs drying if stored open
- Not as stiff as PLA - flex can be unwanted
- Harder to sand and post-process
Best Used For
Mechanical parts
Outdoor enclosures
Water containers
Snap-fit parts
Electronics housing
Living hinges
RC car components
Aquarium parts
Light pipes / diffusers
Niche Tips
Bed adhesion paradox: PETG sticks too well to bare PEI. Use a PEI sheet with a thin layer of glue stick or hairspray, or print on a cool textured sheet.
Transparency: Clear PETG at 0.1mm layers with near-zero fan speed produces genuinely translucent parts - great for light diffusers and lamp shades.
PETG is more moisture-sensitive than PLA. If you hear crackling or see foam/bubbles in the extrusion, dry at 65°C for 4-6 hours.
Stringing fix: Lower print temp by 5-10°C, increase retraction distance, enable "wipe on retract." Combing mode helps too.
Storage & Humidity
Target: below 25% RH. PETG is a moderate moisture absorber. Unlike PLA, moisture visibly degrades quality within hours of open-air exposure in humid environments - expect stringing, bubbling, and reduced layer bonding.
Drying wet PETG: 65°C for 4-6 hours. PETG's higher Tg (glass transition temperature) allows drying at higher temps than PLA without spool deformation.
If stringing suddenly gets worse on a roll that's been sitting out, dry it before touching retraction settings. Wet PETG strings like crazy.
Bed Adhesion
Best surfaces: Textured PEI with glue stick, BuildTak, glass with hairspray. PETG is unusually sticky and needs a release agent on smooth PEI.
Critical warning: PETG on bare smooth PEI without a release agent can bond so strongly it tears the PEI sheet surface when removed. Always apply a thin glue stick layer or hairspray before printing PETG on smooth PEI. This is one of the most common expensive mistakes in 3D printing.
Recommended bed temp: 70-85°C.
Release: Wait for full cool-down to room temperature - PETG tears and leaves residue if removed warm. If still fused after cooling, place the build plate in the freezer for 10 minutes.
Variants & Special Types
PETG ProPremium PETG with better flow consistency and reduced stringing. Generally easier to dial in than standard PETG.
PETG RapidOptimized for faster printing with modified flow characteristics. Maintains layer adhesion at higher speeds.
PETG-CFPETG with chopped carbon fiber. Increased stiffness, reduced warping, matte finish. Popular for drone frames and structural brackets. Hardened nozzle required.
PETG ESDElectrostatic dissipative PETG for electronics environments. Better chemical resistance than PLA ESD, making it suitable for industrial settings.
PETG FX120High-temperature PETG variant with higher heat deflection than standard PETG. Bridge between PETG and engineering materials.
PETG V0 / FRFire-rated PETG meeting UL94 V0 flame classification. For enclosures near heat sources or applications requiring fire safety certification. Significantly more expensive.
References
- Prusa Knowledge Base - PETG. Print temperatures, chemical resistance, and material properties. help.prusa3d.com/article/petg_2059
- Bambu Lab Wiki - Filament Guide Material Table. Glass transition temperatures and printing parameters for common filaments. wiki.bambulab.com/en/general/filament-guide-material-table
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Frequently Asked Questions
Is PETG food safe?
PETG is the same base polymer used in food packaging and water bottles (PET), and some PETG filaments carry food-contact certifications. However, FDM-printed parts have layer lines that harbor bacteria and are difficult to sterilize. For food contact, use a food-safe coating to seal the surface, or limit use to dry goods and single-use applications.
Does PETG need an enclosure?
No. PETG warps much less than ABS and prints reliably in open air at typical room temperatures. An enclosure is unnecessary for most PETG prints. Extremely large parts or drafty environments may benefit from enclosure, but it is not a requirement for the material.
Why does my PETG string so much?
PETG is inherently stringier than PLA due to its higher viscosity and tendency to ooze. Reduce stringing by increasing retraction distance (4-6mm for Bowden, 1-3mm for direct drive), lowering nozzle temperature by 5°C increments, and enabling wipe/coasting in your slicer. Keeping PETG dry also helps - wet PETG strings significantly worse.
Can PETG be used outdoors?
PETG has better UV resistance than PLA and does not degrade as quickly in sunlight, but it is not fully UV-stable. For short-term outdoor use (months), PETG works well. For permanent outdoor installations, ASA is the better choice. PETG handles rain and temperature swings well, with a glass transition around 80°C.