Essentials of Drying Filament: What is the Best Way?


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No doubt, newer inventions are making our life easier and smarter. But at the same time they are pushing us into more complex and bothersome activities. Drying the 3D printers’ filaments is one of them. 

In short, you can go for any and every method— general or specialized— to dry your filament before you feed it to your printer.

Essentials of Drying Filament

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Essentials of Drying Filament

Why Do You Need to Dry Filament?

Put simply, your 3D printer needs dry filament to shape up 3D prints. Moist filaments are incapable of being fused and shaped easily. Here comes the necessity of drying filaments.

Basically all polymers can take up water. Some more than others and with different effects on your parts. Most prominent of them are nylon, flexibles, PCA and PVA, and that’s why, it’s not a good idea to store them just on your shelf.

But there are more. ABS, ASA and co-polyesters like PETG, E3Ds and edge materials take up water right from the air which degrades their print quality and material property.

How Do You Know It Was Wet Filament?

Wel filaments show unusual behavior during the printing process and cause certain types of degradation in the print.

But, unfortunately, there is almost no way to know, without a lab test (or before a print), if your filament is wet and susceptible to a faulty print.

This is simply because the filaments are, from a layman’s eye, of plastic kind and you cannot detect, with your bare eyes, if they have absorbed moisture. Moreover they come in polythene-wrapped rolls and can, by no means, be ‘wet’ until you get them out.

It is, in fact, after printing one or two pieces that you know that your filament somehow absorbed moisture. So how do you know it?

You notice three things:

Mechanical Properties:

Changes in mechanical properties. For example, parts printed with wet PEGT are supposed to be less strong. What happens here is that as the water absorbed into the filament rapidly boils off, as it gets heated in the hotend, the motion of the steam tears apart the polymer chain that gives a plastic its durability.

Even though your parts might look fine, as the polymer itself is supposedly altered, they might perform very differently than what you’d expect. And that’s the exact reason why resin prints are often brittle. When you optimize resin for longer chains it makes it harder to print with.


The second thing you might see is stringing. As the moisture boils off it creates little puffs of stream and those push the molten filament around.

At this point, in a hotend, there is only one way out is left— through the nozzle. This results in having less control over the flow of the molten filament and you see thin strings like spider webs.


The third thing is the increased amount of smell. Though it’s hard to measure for a scientific study you can generally notice the odor.

Other prominent symptoms include

  • Inconsistent extrusion lines.
  • Textured or uneven surface of the prints.

There is, however, another way that could save you the cost of one or two prints:

Let some fused filament come out of the nozzle and watch it carefully when it is released. If you see any bubbles (they can be as small as those fizzing out of your cold drinks), hear any whizzing sound or see steam coming out of the molten material you can be sure your filament absorbed moisture.

Best Ways to Dry Your Filament

Once you know that your filament has somehow taken up water you go for drying it. There are a number of ways to do it. 

1. Filament Dryer

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If you have a system or device that is specially designed to dry your filament that should be the best choice for you. Fortunately, there are more than one filament dryer available in the market. 

Some of them have a two-way drying system. One is during printing. They have got little grommets on the side letting a string of dry filament out straight to your printer when you are printing, confirming an optimum quality print. The second system they provide is kind of ‘post drying print’ meaning you dry your filament first and then feed your printer as usual.

The container of the dryer generally has a temperature selection dial so you can set temperatures for different filaments.

Different dryers use different methods of drying. But using them is always simple. Among the pros of dryers the best one is that your oven and food dehydrator remain spared for their own job.

2. Oven

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If you think buying an extra device is kind of inconvenient you may find your oven an excellent utensil to dry out your filament. It does the same job as the dryer. Throw your filament spool into the oven, set the temperature accurately and wait for a couple of hours. The longer you heat it the dryer it’ll get.

Here is the list of optimal temperatures and duration of drying time

No.MaterialsDrying TemperatureDrying Time (Hours)
1PLA40-50°C (104 – 122°F)3-5
2ABS65-70°C (149 – 158°F)3-6
3PETG/CPE65-70°C (149 – 158°F)3-6
4Nylon70-90°C (158 – 194°F)4-6
5Desiccant60-70°C (140 – 158°F)3-5
6PVA40-50°C (104 – 122°F)8-12
7TPU/TPE45-55°C (113 – 131°F)4-5
8ASA55-65°C (131 – 149°F)4-6
9PP50-60°C (122 – 140°F)5-8
10HIPS55-65°C (131 – 149°F)4-6
11PC70-90°C (158 – 194°F)6-10
12PEEK65-75°C (149 – 167°F)6-8

However, you’ll have to remember two cons of using your oven. 

  • First, tuning and maintaining exact temperature. If your oven is not perfect at maintaining the selected temperature you are likely to have a ‘not perfectly dried’ filament or end up having a spool full of fused filament. So you need to check your oven before you do it.
  • Secondly you need to remember not to put the spool in until your oven reaches the target temperature. All ovens typically overshoot the target temperature while heating up to reduce initiating time. If you place your spool right at the beginning, your filament could get fused.

3. Food Dehydrator

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If you don’t have a qualified oven (remember the above point?) or if you just want to avoid the risk of melting your precious filament your second choice could be the food dehydrator.

The best feature of the food dehydrator is that it does not operate at higher temperatures. It just extracts the moisture by accelerating surface evaporation at a pretty warm temperature thus minimizing your energy consumption and zeroing the risk of fusing your filament.

4. Vacuum

A less tested but probably more eligible than food dehydrator is a vacuum. 

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A vacuum reduces the boiling point and thereby helps when trying to reduce the moisture content because it is easier for the moisture to get out of the material. 

5. The Air Conditioner

This might sound kind of a life hack but the reality is that your air conditioner has an intrinsic feature of reducing humidity. Therefore if you have to keep your unboxed filament spool unused for a long time you can very well keep it in any air conditioned room and be sure to have a healthy filament for your next print.

Vacuum vs Dehydrator—What’s the Best Way?

It’s obvious that both vacuum and dehydrator have the upper hand in drying filament as they consume less energy. Now we’ll compare the two which should help you decide for any one of them.

There are some problems with using your oven that you just cannot avoid even if you set your temperature at the right target. One of them is over-drying of the material. This means that the additive that makes the material less brittle can be damaged because of exposure to heat for a long time.

There is also fear of the polymer getting oxidized. This is not an easily detectable event and does not happen regularly. In fact, you cannot tell when such mishap will occur. It depends largely upon the material and, more particularly, the manufacturing process which can vary any time.

The vacuum is free from the above menaces. But it has got its own problem. You will be burdened with a pump and an extra drying system which clearly means additional expenditure.

The second con is even more disappointing: the moisture reduction of a vacuum has been proved to be far less than the processes that use heat.

Keeping Your Filament Dry— an Easier Step

The above discussion of drying processes are all applicable for those filaments that have already taken up moisture to some extent. If you are cautious enough you can keep it dry and avoid the entire bothersome activities of drying them.

Once you break the seal of the spool your maintenance against ‘getting wet’ begins. The best idea is to keep your spool in any plastic box where they should be safe.

Second thing is that you should not take months to use up a spool. The more you take time the more the risk grows. The best practice is to gather a series of printing jobs that should finish a spool.

Final Words

For commercial users the question of drying the filaments doesn’t bother because of the rapid consumption of spools. All the headaches are for the home users.

But the good news is that you can keep yourself on the safe side by taking only two simple measures (taken from the entire discussion): either keep your half used spool in any air conditioned room or get a plastic box with a tight cover. That should keep your filament— indifferent of the material— dry even for months.

Shamim Ahmed
Shamim Ahmed
I’ve been an innovator in this space for years and am really excited to share my knowledge with you. I’m an entrepreneur and love helping others achieve their goals by teaching them how to build a business around the newest innovations in technology.

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