What is PETG Plastic?

You’ll often see references to PETG in one or more of the following forms: PET, PETE, PETP, PET-P, PETG, GPET, PETT, and others. These can be confusing to someone who is trying to understand the differences between them and what effect any of the suffixes would have (if any) on their 3D printing experience.

PETG is the most common form of PET used for 3D printing filament. The G stands for glycol-modified, and this makes the resulting resin more clear and less brittle than raw PET. Raw PET typically isn’t used for 3D printing. PETE, PETP, PETT, and PET-P are modified versions of PET (called copolyesters), but by far the most common material used in 3D printing is PETG.

For the purpose of this article, I’ll use PETG as a catch-all term to describe the different variations of the 3D-printable filament.

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And what is PETG Filament used for?

In short this is a really tough material, it’s extremely durable and prints without odour. Once you’ve dialed in the correct print settings, it prints nicely too. Users report similar finish quality to PLA.

Here are the main benefits to printing with this material and common PETG filament properties:

  • Very durable, it’s more flexible than PLA or ABS, but also a little softer. You’d have a hard job breaking it in half, so if an ‘unbreakable’ case or enclosure is what you need, PETG trumps pretty much everything (except, Nylon 12).
  • It has very low shrinkage, and therefore no warping. Ideal for printing big stuff.
  • PETG is also very strong, it’s not brittle but can be scratched more easily than ABS which is harder.
  • PETG plastic makes a terrible support structure, because it sticks so well. But because it sticks so well, layer adhesion is fantastic, so prints come out strong.
  • It sticks well to the print bed too, so be careful when you’re removing it after printing.
  • It has a great chemical resistance, along with alkali, acid and water resistance.
  • Odourless when printing.

Typically Polyethylene filament is supplied in a range of translucent colours, and prints with a nice glossy finish.

It makes it ideal for printing anything that needs to be shatterproof or translucent. Many are taking the leap from using PLA or ABS to just using PETG.

Here’s a quick rundown of PETG vs ABS:

  • PETG is more durable than ABS, but ABS is harder, and more rigid.
  • PETG has a lower glass transition temperature, at 80C compared with ABS’s 105C
  • ABS is approximately 20% less dense than PETG.
  • PETG won’t warp like ABS might (if printed incorrectly) and is generally odourless.
  • PETG is more chemically resistant, and so cannot be acetone smoothed like ABS.

Here’s a quick rundown of PETG vs PLA:

  • PLA is more brittle than PETG, unless you want to try to anneal it.
  • PLA and PETG have very similar densities.
  • PETG will need a heated bed, whereas PLA can be printed cold.
  • Layer adhesion with PETG is typically unmatched, leaving very strong and durable prints.
  • PLA prints supports easily to remove, whereas these are harder (but not impossible) to remove with PETG.