How to Dry PETG Filament?

by Mike Brooks | Last Updated: February 10, 2022

3D printing filament absorbs moisture, which affects the effectiveness of the filament material during the printing process.

How to Dry PETG Filament

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The hygroscopic filaments, such as the PETG and ABS filaments tend to absorb water, making them wet. As a result, 3D printing enthusiasts end up getting poor-quality products.

Anyone working with prints needs to take preventive measures to avoid filament spools from absorbing moisture during storage.

As a 3D professional or a hobbyist, you need to know your way around drying PETG filaments in case they get wet.

How to Dry PETG Filament the Easy Way

To dry your PETG plastic filament, you need to put it in a convection oven or a dehydrator (check at Amazon). Then adjust your oven or dehydrator temperature to 65 degrees Celsius (PETG filament glass transition temperature).

Dry it up for six to eight hours and it will be suitable for use with your 3D printer.

This article provides in-depth information on PETG plastic filaments, how they absorb water, and the most favorable ways around drying and storing them.

What Is PETG Filament?

PETG stands for Polyethylene Terephthalate Glycol, a popular filament combining the best qualities from both ABS and PLA filaments. It picks the mechanical and rigidity aspects of ABS plastic and the easy-to-print quality of PLA filaments.

Additionally, it is glycol-enhanced, giving it the unique clear visual property in 3D prints, making them sparkle like glass. PETG offers a few advantages, including:

Differences Between Dry PETG and Non-dry PETG Filaments

3D filaments absorb moisture when left in the open for extended durations running into weeks and months. Therefore, PETG filament remains susceptible to wetting up if not stored in a dry box.

Dry PETG filaments produce glossy products that have a consistent finish as opposed to wet PETG that looks more brittle. Additionally, non-dry PETG filaments produce textured 3D print models instead of a satin finish, due to air bubbles found in the filament voids.

The Hydrolysis Process and Its Impact on PETG Plastic Filaments

Scientists define a polymer as a long chain of monomers. The polymerization process enables monomers to join together in a chain that can readily degrade.

There are several ways that polymer chains can be broken down. One of the best-known reasons for the degradation of polymers remains the Hydrolysis process.


The hydrolysis process kicks when the water molecules break down polymer chains. Additionally, the process takes place in a very complex chemical change process that ultimately affects the material properties of the polymer.

The chemical process serves to significantly increase or decrease the length of the polymer chain. Also, whenever it happens material properties of the polymer such as the tensile strength and clarity get affected negatively.

Effects of Hydrolysis

The hydrolysis process impacts negatively the 3D printing process. When printing and you extrude wet PETG filaments the water in the plastic material boils and forms air bubbles.

The air bubbles break down the polymer chain in a process that shortens up the chain hence weakening the material.

In the process, it creates voids in the filament’s basic structure which weakens the inner-layer-adhesion. This results in an undesirable 3D print surface finish.

How to Know When Filament Is Wet and Needs Drying

All polymers tend to absorb moisture from humid air during their shelf life due to their hygroscopic nature, but at different levels and with various implications on print quality.

On the other hand, hydrophilic polymers absorb water while the hydrophobic polymers remain their complete opposite, meaning polymers don’t absorb water.

Different humidity levels affect the 3D printing quality differently.

A higher humidity level causes the print to end up with stringings at the edges and the corners; it also causes poor surface quality and turns smooth parts rough.

Conversely, a lower humidity level causes a slight negative impact on the final print. Little moisture doesn’t cause bubbles and popping sounds, nor does it cause changes in mechanical properties.

Signs Indicating a PETG Filament Is Wet

As an enthusiast, you might find it challenging to point out whether a PETG filament is wet or not by simply looking at it. Here are a few indicators that can help you out:

These remain some of the most significant tell-tale signs that you are dealing with a humid PETG filament. Interestingly, there are efficient ways around drying your filaments in case you find yourself in this situation.

Moreover, you can always prevent the filaments from getting wet instead of having to dry them.

Managing Moisture Through Proper Filament Storage

A 3D printer cannot function without plastic filaments, which are an essential part of determining the quality of the products. 3D printing hobbyists need to care for the filaments through proper storage mechanisms to prevent moisture absorption.

One option you have is maintaining your filament storage space in low humidity and a well-aerated area. Avoid very warm rooms that may result in a damp atmosphere and encourage moisture accumulation.

Using airtight and vacuum bags is also an excellent way to go. Along with them, you can use desiccant packets and humidity monitors to keep an eye on the relative humidity in your storage space.

Lastly, dry boxes are also a way to go but may stand as more costly than the airtight and vacuum bags.

However, if the moisture beats you to it, there are convenient options to dry your filaments as you will see later in this article.

Requirements for Drying PETG Filaments

As a printing enthusiast, you need to know the requirements of drying up a wet PETG plastic filament. To determine if you need to dry up the filament, you must confirm that they have absorbed a significant amount of moisture.

You may check how long you left the filament exposed to humid conditions. Alternatively, you may listen to the extruding sounds as you print to determine whether it is a dry or wet PETG filament.

A crucial requirement when drying your PETG filaments is to maintain the temperature at 65 degrees celsius; leave them to dry for over six hours to get the best outcome. Alternatively, you can dry it up at temperatures below 65 degrees celsius but for an extended period.

Drying PETG Under the Sun

3D printing hobbyists tend to experiment with drying filament under the sun. Another reason for trying this process out is that it stands as a costless process compared to purchasing expensive filament dryers.

However, you need to appreciate that as much as the sun appears hot in some quarters, it may not be the best idea for PETG filament drying.

The outside surface temperature stands at approximately 30 degrees Celsius and may reach around 45 degrees Celsius in some of the hottest parts of the world.

PETG’s glass transition temperature stands at 65 degrees Celsius, meaning the sun can never get the filament hot enough to remove moisture through the evaporation process. Furthermore, the wet filament tends to absorb more water as it sits outside in a high humid environment.

What Do You Need to Dry Your PETG Filament?

The whole process of drying filaments is slow and requires a lot of precision and care. Therefore,  hobbyists will need the services of a homemade or a specialized filament dryer to carry out this task.

You can also opt to use an ordinary oven or a food dehydrator to achieve similar PETG filament drying outcomes.

3D printing professionals and enthusiasts use filament dryers as essential equipment in the 3D print process. Designers of filament dryers ensure that the enclosed dryer heats the air inside the chamber to dry your filament.

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Heating the PETG filament to the correct temperature breaks the polymer chains, leading to the water molecules boiling and evaporating. As mentioned earlier, you need to set the correct PETG glass transition temperature of 65 degrees celsius to get the best results.

The filament dryers boast extra features that help mount and rotate the filament spools for even heat distribution in the chamber. It also has fans fitted into it to assist in the proper circulation of air to help the filament dry.

The PETG filament drying process may not necessarily need a filament dryer as an electric oven in your home can get the job done. You will need to set the correct temperature for the cooker or oven before placing your PETG spool for drying.

Ensure you set your oven to a temperature that falls below the PETG glass transition temperature for the plastic to heat up and release the moisture.

It is advisable to wait for the oven temperatures to stabilize before placing your spool inside, to prevent melting.

The recommended drying duration remains between four to six hours.

You may repurpose a food dehydrator and use it as another great tool for drying PETG filaments. More so, the food dehydrator will come in handy if you lack access to a filament dryer or an electric oven.

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Designers manufactured food dehydrators to dry fruits, with the ability to work under lower temperatures than the electric oven.

It makes it readily usable for drying up filaments, such as the TPU filament, wet nylon, ABS filament, and the PLA filament, which prefer a lower drying temperature.

Precautions You Need to Take Before Drying PETG Filament

You can always dry your wet PETG filament using a convection oven or a dehydrator and get great results. Often, 3D hobbyists tend to focus on adjusting the correct glass temperatures, drying the filament, and for the suitable drying duration.

However, some other factors may be out of your control, which you equally need to keep an eye on before setting out to dry PETGplastic filaments:

Drying Times and Temperatures for PETG and Other Filaments in a Dryer

The 3D printing industry boasts numerous plastic filaments that 3D printers use to manufacture process prints effectively. A 3D printer can utilize different plastic filaments to print varying models for application in various industries.

All these plastics have different glass transition temperatures and heating durations that consider their unique mechanical properties.

Is PETG Plastic Filament Costly?

In 2017, PETG plastic filament became a very popular filament in the 3D printing industry. Its lower costs compared to other printing filaments like PLA, ABS, and CPE accounting for this popularity.

Also, PETG plastic endeared itself to 3D printing hobbyists because it provides many more industrial benefits. Generic PETG versions trade at $30 and $40 while the specialty formulations go at $45 and $70 making PETG one of the cheapest plastic filaments available in the market.


The PETG filaments, just like other hygroscopic plastic materials, absorb moisture from the environment. This moisture tends to affect the mechanical properties of the filament and, in effect, negatively impact the 3D print quality.

The print surface finish remains one of the critical indicators of the overall quality of the final 3D product. Moisturized and softened PETG filament generates poor surface finishes, while a dry filament guarantees a good product with solid parts.

Therefore, with the knowledge you have attained from the article, you can now protect your PETG filament from wetting up or drying it when it gets wet.

Michael Brooks is the founder of He sees a very bright future for 3D printing that's why his mission is to try and make this easy for everyone. Discover your hidden talent and creativity. You can follow here: Facebook, Twitter & Pinterest.