Ready to start working with a high-quality, versatile, and durable material? This guide covers everything you need to know about working with PETG and other PET materials.
PETG (polyethylene terephthalate glycol) is a material fabricated using modified polyethylene terephthalate (PET), which is commonly used plastic for manufacturing water bottles. Objects manufactured using PET/PETG are semi-rigid with good impact resistance but have a somewhat soft surface, making them prone to wear over time depending on their shape and applications.
The material also has excellent thermal processing characteristics, allowing the plastic to cool efficiently with minimal warping. It is heat-resistant and notoriously tough. PET filaments are particularly popular because they are typically food-safe; as always, before printing anything that will be used in contact with food or skin, consult the fine print of the filament spool you are working with to ensure that it is safe.
PETG, PETE, and PETT are PET variations that are widely available for 3D printing. This guide covers all the essential information you need to print with PETG and related modified PET materials.
Working with PETG
PETG is known for producing a smooth finish prints and adhering well to print beds without exhibiting too much warping. Unlike some similar materials, it is mostly odorless during printing. No material is perfect, though—PETG is not a top choice for bridging because the material is very sticky, causing bridges to be difficult to remove without damaging the print. It is also hygroscopic and can be prone to stringing.
PETG has greater density than both PLA and ABS, allowing the final prints to be more durable if properly fused. It is also highly resistant to acids, alkali materials, and solvents, making it suitable for a wide variety of applications.
The main consideration to keep in mind when working with PETG is temperature. A heated bed will make working with this material is extremely useful owing to the material’s thermal properties.
Initial Printer Settings
Before printing with PET materials, your 3D printer should be tuned to ensure it meets the hardware requirements listed below, which are recommended for achieving optimal print quality.
A heated bed is recommended for working with PETG to ensure cohesion. Set the bed temperature between 75 and 90 °C (167 and 164 ℉) and run a small test print to check bed adhesion and layer setting. Adjust your temperature in small increments between these ranges if you need to make the bed warmer or cooler.
This material sets best when it has something to set on that can be lifted or removed from the bed. This is highly recommended because PET materials tend to stick too well to the print bed, making removing larger prints or those with a lot of suction difficult. Most makers recommend working with painter’s tape or an adhesive. There are bed adhesives on the market, but most people use a craft glue stick or hairspray to establish a thin adhesive layer between the printed material and the bed to promote lifting after the print is complete.
If your slicer has built-in PETG material profiles, they can make the initial set up much easier. If not, start with ordinary PLA settings and change the temperature from there. A special hot-end extruder is not required when printing with PETG. The extruder should be set to between 230 and 250 °C (446 and 482 ℉).
A part cooling fan is required to properly set PETG after extrusion. Set the fan to between 20% and 50%. You might still be able to work with PETG if your printer cannot effectively cool prints on its own; consider getting an external fan that is designed specifically for use with 3D printers.
PETG isn’t difficult to work with, but because it has such excellent properties under optimal settings, fine-tuning print settings is always recommended. Starting with the settings described above, print a test object. There are two major things to look out for: stringing and layer delamination.
After evaluating your test print, modify your print settings according to the recommendations set out below. Note that these are material-specific recommendations—if you have more issues with your print, or these recommendations don’t fix the problem, check out our troubleshooting guide to diagnose any underlying printer issues.
The following guidelines can help you achieve perfect PETG prints.
1. Fine-tune retraction and speed settings
PETG is a fairly sticky material, which means that it is prone to oozing. The material’s durability makes strings of molten plastic difficult to break off, making a stringy final print look webby with no easy post-processing that can fix the problem.
These issues can be mitigated by properly tuning print settings such as retraction distance, retraction speed, and travel speed. As always, any changes should be incorporated in small increments. Have a test model file ready to run that has similar support requirements as your actual model so you can print a few test models without using all of your filament.
Print speed is another factor that can heavily influence oozing and layer setting. Most filament manufacturers recommend starting at 50 mm/s. Other makers suggest starting at 25 mm/s for the first layer and outer wall and setting the travel speed to at least 120 mm/s to avoid oozing.
2. Stop the cracks
If you’re used to printing with PLA, your first PETG prints might start cracking, which can be endlessly frustrating after hearing that it’s an extremely durable material. Cracking, like delamination, can occur when the print is cooled too rapidly.
If the print begins separate or crack, reduce the fan speed. PETG has much higher thermal resistance than PLA, so its overhangs and details will still come out sharp without being cooled quickly. By setting the proper cooling time, the material can effectively fuse and form a solid, cohesive structure.
3. Keep it dry
If you notice that your PETG prints are starting to show deteriorating print quality and strength, you might have a moisture problem. As noted above, PETG is hygroscopic, meaning that it absorbs moisture from surrounding air. Moisture can deteriorate prints or the material itself.
When working with filaments like this, it is crucial to keep it stored in a dry environment, such as an airtight bag or box. Some makers also like to use desiccants to draw moisture from the air around the filament.
If your filament is already overly hydrated, it can be carefully dried in an oven at around 60 °C (140 ℉) for two to three hours.
4. Give it space
Your model may require support structures, which are typically easy to implement with FDM printers. However, once your printer settings are optimized, PETG can fuse too well and make supports seemingly impossible to remove without disrupting other areas of the print. Some slicers have settings specifically designed to deal with this problem. Get familiar with your slicer and find the structure distance settings (such as “Support Z Gap”). Adding some space between the support and main structure can make it easier to remove supports after the print is complete.
💡 PETG’s glossy surface is particularly helpful for printing rafts. The surface allows for easy raft separation while maintaining a nice surface finish.
💡 Depending on the model you’re working with, try disabling your part cooling fan for the first layers of the print to prevent warping. This is particularly helpful for larger prints, which are prone to bottom layer warping.