PETG Filament: The Complete Guide for 3D Printing
PETG (Polyethylene Terephthalate Glycol) combines the best properties of PLA and ABS: easy to print like PLA, but significantly more robust and impact-resistant. It is the ideal material for functional parts, mechanical assemblies and applications requiring more strength than PLA. In this guide, learn everything about PETG properties, optimal print settings and when PETG is the right choice.
What is PETG?
PETG is a modified polyethylene terephthalate (PET, known from beverage bottles), with glycol added to make the material more flexible and easier to process. The result is a robust, transparent (or translucent) filament with excellent mechanical properties.
PETG is characterized by the following properties:
- High impact resistance and flexibility (less brittle than PLA)
- Good chemical resistance (resistant to many solvents)
- Higher temperature resistance than PLA (~80 °C)
- Low warping tendency
- Food-safe (pure PETG, without dyes)
- Good layer adhesion
Technical Properties in Detail
| Property | Value | Meaning for Printing |
|---|---|---|
| Print Temperature (Nozzle) | 220–250 °C | Higher than PLA, lower than ABS |
| Bed Temperature | 70–90 °C | Heated bed recommended for best adhesion |
| Glass Transition Temperature (Tg) | ~80 °C | Higher than PLA, suitable for heat-exposed parts |
| Tensile Strength | 50–60 MPa | Similar to PLA, but significantly tougher |
| Density | 1.27 g/cm³ | Slightly heavier than PLA |
| Impact Resistance | High | Significantly better than PLA, similar to ABS |
| UV Resistance | Medium | Better than PLA, worse than ASA |
| Chemical Resistance | Very good | Resistant to acids, bases, oils |
Pros and Cons of PETG
✅ Advantages
- More robust and impact-resistant than PLA
- Higher temperature resistance (~80 °C)
- Low warping tendency
- Good chemical resistance
- Food-safe (pure PETG)
- Little odor when printing
- Good layer adhesion
- Available transparent/translucent
❌ Disadvantages
- Prone to stringing
- Adheres very strongly to print bed (can damage surfaces)
- Hard to sand (smears)
- Hygroscopic (absorbs moisture)
- Not for outdoor use (UV degradation)
- Slightly more expensive than PLA
- Can be sticky with wrong settings
Optimal Print Settings for PETG
Base Settings (Reference Values)
| Parameter | Recommended Value |
|---|---|
| Nozzle Temperature | 230–245 °C (first layer: +5 °C) |
| Heated Bed | 75–85 °C |
| Print Speed | 30–60 mm/s (slower than PLA) |
| Fan (Part Cooling) | 30–50% (lower than for PLA!) |
| Retraction (Direct Drive) | 1–3 mm @ 20–40 mm/s |
| Retraction (Bowden) | 3–6 mm @ 30–50 mm/s |
| Layer Height | 0.1–0.3 mm (0.2 mm standard) |
Troubleshooting: Common Print Errors
Stringing
- Lower temperature by 5–10 °C
- Optimize retraction (small steps: 0.5 mm)
- Reduce retraction speed
- Dry filament (PETG absorbs moisture!)
- Enable Z-Hop (0.2–0.5 mm)
Too Strong Bed Adhesion
- Use release agent (e.g. thin layer of glue stick)
- Clean PEI plate with acetone (matte rather than glossy)
- Lower bed temperature to 70 °C after first layer
- Never print directly on glass (PETG fuses with glass!)
Poor Layer Adhesion
- Reduce fan (max. 50%)
- Increase temperature (240–245 °C)
- Reduce print speed
- Dry filament
Sticky/Unclean Surface
- Lower temperature by 5 °C
- Check for overextrusion (reduce flow to 95–98%)
- Slightly increase print speed
PETG vs. Other Filaments: When to Use What?
| Property | PETG | PLA | ABS | ASA |
|---|---|---|---|---|
| Print Difficulty | ⭐⭐ Medium | ⭐ Easy | ⭐⭐⭐ Hard | ⭐⭐⭐ Hard |
| Impact Resistance | ✅ Very good | ❌ Brittle | ✅ Good | ✅ Good |
| Heat Resistance | ~80 °C | ~60 °C | ~100 °C | ~95 °C |
| UV Resistance | ⚠️ Medium | ❌ Low | ❌ Low | ✅ Very good |
| Chemical Resistance | ✅ Very good | ⚠️ Medium | ✅ Good | ✅ Good |
| Warping | ✅ Low | ✅ Very low | ❌ Strong | ⚠️ Medium |
| Food-Safe | ✅ Yes (pure) | ⚠️ Yes (pure) | ❌ No | ❌ No |
Decision Guide: Which Material When?
- Choose PETG for: Functional parts, mechanical assemblies, housings, impact-stressed parts, chemical resistance
- Choose PLA for: Decorations, prototypes, models without mechanical stress
- Choose ABS for: Heat-resistant parts, post-processing with acetone
- Choose ASA for: Outdoor applications, UV exposure
Application Areas for PETG
Ideally suited for:
- Functional parts: Gears, bearings, brackets, mechanical assemblies
- Housings: Electronics, sensors, controllers (indoor)
- Tools & fixtures: Clamping devices, grippers, adapters
- Food contact: Cookie cutters, funnels (pure PETG without dyes)
- Transparent parts: Sight glasses, covers, displays
- Medical applications: Prosthetics, orthotics (not implantable)
- RC parts: Drone frames, RC car chassis
- Robotics: Grippers, joints, structural parts
Not recommended for:
- ❌ Outdoor applications with UV exposure (prefer ASA)
- ❌ Parts above 80 °C (prefer ABS/ASA/Nylon)
- ❌ High-precision dimensions (PETG can slightly yield)
- ❌ Parts that need sanding (smears)
Storage and Care of PETG Filament
PETG is highly hygroscopic and absorbs moisture from the air. Wet PETG causes bubbling, stringing and poor layer adhesion.
Symptoms of wet filament:
- Audible hissing during extrusion
- Bubbles at the nozzle
- Heavy stringing
- Brittle/fragile layers
- Matte instead of glossy surface
Proper storage:
- In sealed bags with silica gel
- Dry box with dehumidifier (humidity <20%)
- At room temperature, protected from sunlight
- Return to dry box immediately after use
PETG Variants and Special Filaments
Standard PETG
Classic PETG in various colors. Reliable, robust, ideal for functional parts.
PETG Transparent/Translucent
Translucent, ideal for covers, sight glasses, displays. Requires precise settings for best clarity.
PETG-CF (Carbon Fiber)
Reinforced with carbon fibers. Higher stiffness, reduced warping, but abrasive (hardened nozzle required).
PETG Tough
Modified PETG with even higher impact resistance. Ideal for highly stressed mechanical parts.
rPETG (Recycled PETG)
Made from recycled PET. More environmentally friendly, slightly more matte surface.
Our PETG Filaments in the Shop
Frequently Asked Questions (FAQ)
Is PETG food-safe?
Pure PETG (without dyes) is fundamentally food-safe, as it is chemically identical to PET (beverage bottles). However, 3D-printed objects have microstructures where bacteria can settle. Without special treatment (epoxy resin sealing), PETG prints are not recommended for permanent food contact.
Why does PETG stick so strongly to the print bed?
PETG has very good adhesion to PEI, glass and other surfaces. This is normally good, but can be problematic when removing. Never print directly on glass – PETG fuses with glass and can tear out pieces. Use release agent (glue stick, Magigoo) or a PEI plate with matte surface.
Can I print PETG without a heated bed?
Theoretically yes, practically not recommended. PETG adheres poorly at room temperature and tends to warp. A heated bed at 75–85 °C is necessary for best results.
Why is my PETG print sticky?
Possible causes: (1) Temperature too high → lower by 5–10 °C. (2) Overextrusion → reduce flow to 95–98%. (3) Print speed too slow → increase slightly.
Can I post-process PETG?
Yes, but differently than PLA/ABS. PETG is hard to sand (smears), but drills, saws and glues well (super glue works). For smooth surfaces: epoxy resin coating or XTC-3D. Acetone does NOT work on PETG (only on ABS).
How do I dispose of PETG prints?
In Switzerland, PETG goes in normal household waste. Theoretically PETG is recyclable (like PET bottles), but 3D printing PETG is usually not accepted by recycling centers (contaminations, dyes).
Related Guides
- PLA Filament: Properties and Applications
- ASA Filament: The Outdoor Specialist
- ABS Filament: Heat-Resistant and Robust
- TPU: Flexible Filaments for 3D Printing
Note: The information in this guide is based on typical properties of PETG filaments and general 3D printing knowledge. Specific values may vary depending on manufacturer and product line. Always consult the technical data sheets of the respective filament.