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Is PETG Hygroscopic?

Is PETG Hygroscopic? | 3D Printing Spot

Updated by

William Stone


November 2, 2023

Key Takeaways

  • PETG absorbs moisture, and it’s hygroscopic, affecting print quality.
  • Store PETG in a dry environment to maintain quality.
  • Always dry PETG filament before use to prevent printing issues.
  • Moisture affects the appearance and strength of printed parts.

PETG is one of the best and most widely used filaments in 3D printing. It has many qualities that make it ideal for any project, but is PETG Hygroscopic?

Yes, PETG is hygroscopic and can absorb moisture from the air, affecting print quality. Store in a dry environment and dry before use to prevent issues like stringing, blabbing, and poor layer adhesion in 3D printed parts. Moisture compromises appearance and strength.

Over the years, I’ve worked with all of the most common materials used in 3D printing, including ABS, PLA, and, of course, PETG. Through my experiences with these materials, I’ve had plenty of time to experiment with the best ways to store and maintain them. By the time you are done reading, you’ll be able to counteract all of the most common problems associated with the hygroscopic nature of PETG.

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Table of Contents

What Is PETG And What's So Good About It?

PETG is one of the most commonly used materials in 3D printing, and there are plenty of reasons for that. Like most of the other materials used in 3D printing, PETG is a thermoplastic capable of being molded and remolded into any number of shapes and sizes. These properties are why thermoplastics are commonly used for 3D printing temperature monitoring.

In addition to its thermoplastic properties, PETG has a number of qualities that make it favorable to use in all sorts of applications. PETG is very strong, resistant to impact, and able to withstand high pressures,  so it will hold its shape in all but the harshest of conditions.

It's a chemical makeup and water-resistant filament, so it has no problem being exposed to all sorts of harmful acids and bases, not to mention that if used correctly, any object you make with it will be water-resistant.

PETG is even resistant to heat and UV radiation, making it a great choice for any object that's going to be spending a lot of time outside and exposed to the sun.

All of these qualities and PETG’s general cheapness to produce and buy make it no wonder that this hygroscopic material has taken over the world of 3D printing and is used in countless everyday products we use every day. It would be surprising if you didn’t have at least a few products made of PETG lying around your home right now.

Outside of 3D moderate printing temperature, PETG is heavily used in the packaging of food and drink products. PETG is non-toxic and food-safe, making it the perfect hygroscopic material for use in water-resistant bottles, take-out containers, and the packaging for any other consumable good that you can think of.

PETG is also often used in the medical industry, both in the packaging of medical devices and actual medical implants. The rigidness and strength of printing PETG allow it to withstand even the harshest of sterilization procedures, making the material perfect for anything that will be used in the medical field.

What Does Hygroscopic Mean?

Now that we know everything PETG is resistant to and what it's used for, we can focus on one of the biggest drawbacks of printing PETG: the fact that it is Hygroscopic.

But what does Hygroscopic mean? And is PETG hygroscopic?  Basically, if an object is hygroscopic, it means that the object will continuously absorb water from the air humidity until it is fully saturated and unable to take on any more water. The opposite of this is hydrophobic, meaning that even if water is dumped on top of the material, it will not absorb and simply bead up and slide off the print surface.

Saturated or water-logged PETG filament can cause a lot of problems in the outcome of your PETG prints. Firstly, printing PETG that absorbed too much water may not lay properly, causing mild dimensional differences in your PETG print bed that you did not design.

Water can cause some of the bonds in the PETG and its layers to break down, meaning that your print will be significantly weaker than it should be.

How Should You Store PETG?

As stated before, PETG is hygroscopic, meaning that it absorbs moisture content from the air over time. This can cause all sorts of problems, so it’s important to make sure that you are storing your PETG properly.

Since the main problem here is the absorption of water molecules, moisture and air humidity are your two biggest enemies in this case. Simply living in a particularly humid environment of the world can make it a lot harder to successfully care for your PETG.

Because of this, you should store your PETG in an airtight container in a cool and dry part of your home. Obviously, having a dehumidifier close by can help prevent your PETG from absorbing moisture, and the use of vacuum sealing and filament dry boxes can be useful here too.

Though these are the ideal conditions for filament storage, if you don’t live in a particularly humid area, you don’t have to get too fancy. Just make sure that your wet filament is stored in the driest part of the house, possibly away from any possible sources of moisture.

How Do You Know If Your PETG Is Wet?

Though it’s not blatantly obvious that a filament spool of PETG is saturated with water just by looking at it, there are a few obvious signs that you’ll notice if you are using wet PETG to print.

First, you might notice that the surface quality of your print is getting worse, and the layers of your print aren’t layer adhesion as well as they should be. It will be even more obvious if compared to a good print that you have lying around with a smooth surface finish.

If all else is the same, but your print is of significantly lesser surface quality than normal, it is most likely that this is the issue.

Another way you can tell is by simply listening as you print. If you hear any sort of crackling or popping noises coming from the hot end of your printer, this is most likely water evaporating as the plastic is being melted. If you’re hearing these sorts of noises during your printing process, there’s no doubt that the PETG being used is too wet.

What Do You Do If Your PETG Is Wet?

Sovol Filament Dryer
Sovol Filament Dryer

Luckily, even though moisture absorption can cause a lot of problems for your PETG filament, it's not the end of the world if your PETG filament gets wet.

A Hygroscopic filament dehydrator can use a wet spool of PETG filament to get rid of all absorbed moisture. These machines are easy to use and allow you to make your wet filament as good as new again.

Two of the best filament dryers on the market are the Sovol SH01 Filament Dryer and the PrintDry Pro Filament Drying System. These PETG filament dryers, along with many others, allow you to get around the hygroscopic nature of PETG so that you don’t have to be so worried about storing your PETG in the best conditions possible.

PETG Filaments Comparison with Other Filaments

Now, let's talk about how PETG stacks up against its buddies in the 3D printing process world, PLA and ABS.


So, PETG and PLA are like the siblings of the 3D printing family. They share some qualities but are also unique in their own ways. While these PETG  absorb moisture, they are a bit more hygroscopic than PLA. However, PETG is generally more flexible and durable, which is why some folks prefer it for their printing process.


Now, let's compare PETG and ABS. ABS is like the strong, older sibling that doesn't get swayed by a bit of moisture. It's less hygroscopic compared to PETG. However, PETG has the upper hand when it comes to being odorless during the printing process, and it's also known to produce smoother, shinier PETG prints. Plus, it’s a bit friendlier to the environment.

The Preferred Choice

So, despite its tendency to absorb moisture, many people find PETG to be their go-to PETG filament. It's like having a friend who might be a bit high maintenance, but you love them anyway because they're just that awesome. With the right filament storage and a bit of drying, PETG can be just as fantastic as its other PETG filament friends!

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Is PETG Hygroscopic?


William Stone

William Stone

William has spent 20 plus years in the custom manufacturing industry as a COO, CEO and Owner of various custom product businesses. His experience has exposed him to all types of manufacturing from die cast, die struck, injection molding, CNC machining, laser etching, engraving and of course 3D printing.

Learn more about William Stone

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