Printing with PETG

What is PETG?

PET (Polyethylene terephthalate) is the most commonly used plastic in the world. You can find the polymer almost everywhere you look, from your water bottle to clothing fibers, even in your food containers. PET is also used in thermoforming processes and can be combined with glass fiber to create engineering resins.

PETG is a modified version of PET. The »G« stands for »glycol-modified« which is added to the material composition during polymerization. The result is a filament that is clearer, less brittle and easier to use than its base form PET.

The advantages of PETG filaments are transparent colors, and they are resistant to moisture. Because they are transparent we can print the models hollow and use them as lamps. PETG has the best properties of both PLA and ABS. It has the strength of ABS but does not warp or shrink and it is very easy to print like PLA. Similar to PLA, PETG filaments because of their properties (high strength) are not suitable for printing mechanical parts, because they will be very brittle and will break easily.

Printing with PETG

PETG similar to PLA is characterized by high strength and low coefficient of shrinkage (even lower than that of PLA). PETG is printed somewhere between 220-240°C. Similar to PLA PETG too does not need a heated bed, but it is recommended to use it. The bed temperature should be somewhere between 55-70°C. By increasing the bed temperature we’re ensuring a better first layer adhesion to the bed. Because of the fumes that are released when printing it is very recommended to use air filters or print in a well ventilated space.

Cooling

PETG can be printed in an open or enclosed printer. Cooling should be set at around 80%.

Rafts and supports

When printing PETG the use of brim is very recommended. Similar to PLA, with PETG it is not recommended to print on rafts, because they are hard to remove. If you are printing with supports, the infill of those should be low.

Post-processing PETG

PETG can be very easily post-processed mechanically (sanding). The print can then be coated with a two part epoxy, wet-sanded and painted if desired. This adds to the print, makes it much stronger, smoothes it out and gives you a professional finish. The only downside is it takes considerable more time than the acetone vapor method.

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