There are many factors that can adversely affect the quality of a 3d print. Some of the most common factors can be mentioned such as clogged nozzle or hot-end, wrong nozzle size, bad slicer setting, wrong nozzle temperature…
However, one of the factors that can degrade quality, or even ruin an entire 3d print that is often overlooked or rarely mentioned is wet filament
In this article, we will give specific instructions on handling wet filaments, from identification to drying and filament storage methods for future print.
Contents
Signs that your filament is wet
Before we learn how to dry a filament, we need to know the signs that a filament is wet.
There are a number of common signs to identify wet filaments.
Excessive stringing
Stringing (or “hairy” prints) occurs when small strings of plastic are left behind on a 3D printed model. This is typically due to filament dripping out of the nozzle while the extruder is moving to another location.
Here’s an example of stringing due to wet filament:
Besides the cause of wet filament, clogged nozzle, incorrect retraction settings or hot-end temperature too high may also cause stringing. Make sure to check the cause carefully before making the final decision.
Bubbles on the extruded material’s surface
If the extruded materials contain a lot of bubbles on the surface => that’s a sign of wet filament.
These bubbles occur because the filament gets wet, moisture gets trapped in the filament. When the nozzle heats up to a temperature above 100°C, the water vaporizes and expands, creating a series of bubbles in the filament. You will see bubbles clearly when the filament is extruded from the nozzle.
Popping sound when extruding material from the nozzle
Popping sounds when extruding indicate that you have moisture in your filament.
During the extrusion process, if you can hear a small popping, hissing sound or notice some steam coming out near the nozzle => That means your filament needs to be dried.
Inconsistent extrusion
Inconsistent extrusion can be caused by many different causes such as nozzle blockage, wrong temperature… However, this is also a common sign when your filament is wet.
Different parts of the filaments have different degrees of moisture absorption.
When the filament is melted in the hot end, the moisture absorbed in the filament evaporates leading to an increase in pressure in the nozzle.
The increased pressure will lead to an increase in the extrusion rate of the material in a short time. The more moisture is absorbed in the filament, the less consistent the 3d print will be
The filament is brittle and snaps easily
Take your PLA filament and bend it, if the filament is brittle and breaks when bent => This means the filament has absorbed a lot of moisture.
If you dry the PLA filament by exposing it to sunlight or UV light, the PLA filament will lose color quickly and become much more brittle.
Why we need to keep filament dry?
Losing print quality due to stringing
When the filament is wet and causes stringing, the surface of the 3d print will be uneven, and many plastic fibers will appear around the 3d printed product. Due to this problem, the quality of the product deteriorates
Decrease strength of 3d prints
Wet filament will lead to a decrease in the adhesion of the layers of the 3d printed object. When the connection between layers is reduced, obviously the durability and strength of the 3d print will be reduced.
This will only be recognized after you have finished the 3d print and put it to actual use, which is not good at all. Therefore, you should find a way to recognize the moisture in the printed material before putting it into use
Increase the amount of smell
So, you can see that it’s very important to keep your filament dry before 3d printing!
How to properly dry filament for 3d printing
There are different methods for drying filaments. You can use a specialized device or take advantage of the available drying equipment to dry filaments. Even if your 3d printer has a heat bed, you can also use it to dry the filament.
Below I will list the most common methods for drying filaments, just pick the method that you find most suitable.
Method 1: Filament Dryer
Things to prepare
| 3d print filament dryer: Filament dryer is a machine that enables you to dry wet filament. | 
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How it works
Along with the development of 3d printing, a variety of unique products have been invented to support the specialized tasks of 3d printing. And filament dryer is one of those products. A filament dryer can remove excess moisture, keep your filament dry and bring you better prints.
Today, most filament dryers display the humidity and temperature inside the drying box in real-time.
It’s fairly simple to use a filament dryer, just insert your filament roll into the dry box and adjust the temperature and countdown timer to your desired number. Once all are set, close the box and wait. The ideal value of moisture in a filament is between 10-13 %, so you can wait until the humidity drops to 10%.
Depending on the type of filament and degree of moisture, set the appropriate time and temperature. Usually set the temperature at 50 degrees Celsius and the drying time should be about 6-12 hours.
Here are the appropriate times and temperatures for drying different types of filaments in an oven.
| PLA | ~45 °C | 4-6 hours |
| ABS | ~70 °C | 5 hours |
| NYLON | ~80 °C | 10 hours |
| TPU | ~45 °C | 4 hours |
| ASA | ~80 °C | 4 hours |
| PC | ~120 °C | 6 hours |
To test the effectiveness of the dehumidification process, try weighing the filament before and after drying. You will notice the weight difference before and after drying the filament. In the example below, the difference before and after drying is 6 grams (which is moisture’s weight), which is quite significant.
Just my 2 cents about choosing a filament dryer is that you should choose a type that can dry evenly around the filament and preferably with a visual temperature/humidity display.
Reference video:
| Pros: Easy to operate and highly efficient because the filament dryer is a specialized machine for drying filaments. | Cons: The price is not cheap at all for a simple drying solution, it will cost you about 50-70 dollars and |
Method 2: Cooking Oven
Things to prepare
| Cooking oven: a popular appliance that used for roasting and heating food | 
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How it works
Using a cooking oven to dry filaments, sounds crazy right? However, this is a proven method that is being widely used by many experienced 3d printing users.
Due to the nature of the oven to cook food by heating the air, you can fully utilize it to evaporate the moisture in the filament.
To use the oven to dry filaments, simply put the filament reel in the oven and adjust the temperature accordingly. However, there are some important notes below so that drying filaments in the oven does not become a terrible disaster
- First, be careful not to use a microwave oven if you don’t want to damage your filament. A microwave oven heats air using microwaves, a form of electromagnetic radiation similar to radio waves. So the moisture inside the filament will boil and damage your filament
- The second thing you need to note is the operating mechanism of a cooking oven. The Cooking oven will raise the temperature slightly above what you set. If this temperature exceeds the glass transition temperature of the filament it will cause your filament to soften the plastic and fuse parts of the filament together. (eg: The glass transition temperature of PLA lies between 55 to 60 °C, so the safe drying temperature should be 40-45) (The glass transition temperature of PLA lies between 55 to 60 °C)
=> You should preheat the cooking oven first, then use an infrared thermometer to measure the actual temperature inside. When the temperature is at a safe level, we put the filament in to dry - You should dry the filament in the oven for 4 to 6 hours for the moisture to completely evaporate
- ABS and PLA may give out nasty fumes when drying with oven, so if you don’t use the oven to cook immediately after drying the filament to ensure food safety
Here are the appropriate times and temperatures for drying different types of filaments in an oven.
| PLA | ~45 °C | 4-6 hours |
| ABS | ~70 °C | 5 hours |
| NYLON | ~80 °C | 10 hours |
| TPU | ~45 °C | 4 hours |
| ASA | ~80 °C | 4 hours |
| PC | ~120 °C | 6 hours |
Reference video:
| Pros: Very convenient and economical because most families own a cooking oven. | Cons: Low-quality oven may not able to maintain a constant temperature during the drying process => it may melt the filament, causing the filaments to stick together and you will not be able to use them later.
Some filament types may give out nasty fumes, causing odors on the oven |
Method 3: Food Dehydrator
Things to prepare
| Food Dehydrator: a popular appliance that used to dry fruits or vegetables. | 
|
How it works
This is an economical and also very effective solution for drying filaments. Food dehydrator is mainly used to dry fruits or vegetables, so the temperature is not as high as an oven, which is very suitable for drying filaments.
Depending on the size, the food dehydrator can be used to dry 1 to 2 filament reels at once.
If you use a universal food dehydrator like the one below, it will usually only dry 1 filament reel.
Some food dehydrators like Chefman 9-Tray Food Dehydrator below have more spacious compartments, you can dry 2-3 filament reels at a time. Depending on your needs, make the most suitable choice
Reference video:
| Pros: the most cost-effective solution for drying filament. | Cons: The main limitation of using a food dehydrator is capacity. You can only dry one or two filament reels at a time, depending on the size. |
Best Temperature & Drying Time for every type of filament
Each type of filament has its own suitable drying temperature as well as drying time.
Depending on the actual moisture content of the filament, the drying time may be increased or decreased.
The table below summarizes the appropriate drying temperatures and times for the most common types of filaments available today.
| Type of filament | Drying Temperature | Recommended drying time |
|---|---|---|
| PLA | 45°C | > 3h |
| ABS | 70°C | > 3h |
| PETG/CPE | 55°C | > 3h |
| Nylon | 75°C | > 12h |
| Desiccant | 60°C | > 3h |
| PVA | 40°C | > 10h |
| TPU/TPE | 50°C | > 4h |
| ASA | 55°C | > 4h |
| PP | 50°C | > 6h |
| HIPS | 55°C | > 4h |
| PC | 120°C | > 6h |
| PEEK | 80°C | > 6h |
Usually, the ideal drying temperature is a bit lower than the glass transition temperature of the material.
Store filament and keep filament dry for future use
Things to prepare
Storage Boxes to store filament |
Store filament in Vacuum Bag |
After drying the filament, an important step you need to take to ensure that the filament won’t get wet in the future is to properly store and care for the filament.
The best way to prevent filaments from getting wet is to store filaments in a dry place with low humidity.
If you don’t need to store too much filament then use Storage Boxes or Vacuum Bags and add some Silica Gel to absorb moisture.
If you don’t mind spending some money, then dry boxes are the best solution to keep your filament dry all the time.
Summary
Through this article, I hope you have understood the importance of keeping the filament dry and know the steps to take to dry a wet filament.
If you have other methods of drying or storing filaments that you are working on, please share them in the comments section below. I really appreciate your contributions and sharing, they will surely help many other 3d printing users.
