Most 3D printing discussions default to PLA. It's the cheapest, easiest material to print with, and it works beautifully for decorative objects, display models and anything that lives at room temperature in a dry environment. But for functional parts — things that have to do something, be somewhere specific, or survive conditions that aren't controlled — PLA has serious limitations that people don't always appreciate until it fails.
PETG is our answer to this. We print exclusively in PETG at 3D Guru, and this guide explains why.
Heat resistance: where PLA falls short
PLA begins to soften at around 60°C. This sounds like it should be high enough, but in practice it catches people out regularly:
- A car dashboard on a sunny summer day can exceed 80°C
- An electronics enclosure housing a Raspberry Pi or similar can run at 50–65°C
- A bracket near a heating vent may regularly hit 55–70°C
- A windowsill in direct sun in summer can reach 60–70°C
In any of these situations, PLA parts don't suddenly shatter — they slowly deform. Brackets sag. Clips stop holding. Enclosures warp so lids no longer close. The failure is gradual and sometimes only noticed when the equipment it was holding falls off the wall.
PETG maintains its shape up to approximately 80°C continuous use. This doesn't make it suitable for everything — engine bays and direct heater applications can exceed this — but it covers the vast majority of real-world functional applications where PLA is marginal.
Impact resistance and toughness
PLA is somewhat brittle. When subjected to sharp impact, it tends to crack or shatter rather than deform. PETG is tougher — it has better impact resistance and a tendency to flex slightly under load rather than snap. For anything subject to knocks, drops, vibration or mechanical shock, PETG's toughness is a meaningful advantage.
This is particularly relevant for:
- Workshop jigs and fixtures handled repeatedly
- Automotive clips subject to vibration
- Parts in machinery with moving components nearby
- Anything likely to be dropped or mishandled
Moisture resistance
PLA absorbs moisture over time, which causes it to become brittle and can cause dimensional changes. In outdoor or humid environments, PLA parts can degrade surprisingly quickly — becoming chalky in texture and losing mechanical properties. PETG is significantly more moisture-resistant and holds its dimensions in damp conditions far better.
For parts that will live outdoors, in bathrooms, kitchens, garages or any other humid environment, PETG is the clear choice.
Chemical resistance
PETG has reasonable resistance to oils, greases and many common chemicals. PLA is susceptible to degradation from oils and can be attacked by alcohols. For workshop or automotive applications where the part might come into contact with cutting fluids, lubricants or cleaning agents, PETG holds up significantly better.
Layer adhesion
PETG has better inter-layer adhesion than PLA when printed correctly. This means a PETG part is stronger along the Z axis (perpendicular to the build plate) than a PLA part of equivalent geometry. For parts loaded in unusual orientations relative to their print direction, this improved adhesion is meaningful.
When is PLA the right choice?
PLA is excellent for:
- Decorative objects and display models
- Prototype geometry checks where function doesn't matter
- Objects in stable, room-temperature, dry environments
- Applications where the lowest possible cost matters more than durability
Summary comparison
| Property | PLA | PETG |
|---|---|---|
| Heat resistance | ~60°C | ~80°C |
| Impact resistance | Moderate | Better |
| Moisture resistance | Poor | Good |
| Chemical resistance | Poor | Moderate |
| Print difficulty | Easy | Moderate |
| Suitable for vehicles | No | Usually yes |
We've made the choice simple: everything we print at 3D Guru is PETG. If you need a functional part, that's the right material.
Common questions
Is PETG stronger than PLA?
PETG is tougher rather than stiffer. PLA resists bending slightly better, but PETG absorbs impact instead of shattering, which is what usually matters on a working part.
Will a PLA part melt in a car?
PLA softens from about 60°C and a parked car dashboard can pass 80°C in summer, so PLA parts sag over weeks. PETG holds its shape to roughly 80°C.
Can PETG be used outdoors in the UK?
Yes. PETG shrugs off rain and damp and holds up far better than PLA in sun. Over several years of direct UV it slowly loses toughness, so add thickness.
Is PETG food safe?
The raw plastic is food contact approved, but a printed surface has layer lines that trap residue. We treat printed parts as fine for dry or brief contact only.
Which should I choose for a replacement part?
Almost always PETG. A replacement has to live where the original lived, often warm, damp or under load, and PLA is the material most likely to quietly deform.
Do you print in PLA at all?
No. We print every job in PETG so there is no risk of a part arriving in the weaker material. If your job genuinely needs something else, we will say so.
Published 9 September 2026 · last reviewed 5 October 2026.
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