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Is Drying Filament in the Microwave Oven Effective?

3D printing is the art of printing solid objects from different materials like plastic, resin, and even metal. The image of the object is collected from a digital file, and the tangible object is then created by joining successive layers of material. A single thread of the material used is called a filament. 

A microwave oven is an effective way to dry filaments. Place the filament in the microwave and then set the temperature. However, you need to be careful about the temperature because it is hard to control the heat inside a microwave oven, and a lot depends on the filament material. 

If you are wondering if you can use a microwave to dry filaments, you have found the right article. Here, I will explain why filaments need to dry and whether you can use a microwave for this job. Keep reading! 

Why Do You Need To Dry Filaments?

For the 3D printing process to run correctly, preparing the filament and keeping it dry is essential. Heating the filament at the appropriate temperature eliminates moisture that could be absorbed during storing. 

You need to dry filaments to ensure the end product is not damaged. Filaments are made of chains of molecules. Moisture leads to water in molecules that disrupt the chain and ruin the filaments, causing lots of difficulties while printing. 

If you use filaments right after opening them, you should not worry too much about drying. If you are tossing them in a corner, then you need to be careful. It is very easy for some materials to absorb moisture, even in seemingly ‘dry’ places. 

Adverse Effects of Moisture on Filaments 

Moisture ruins a filament and eventually the final product in multiple ways. In many cases, the final product turns out to be grainy or coarse. 

When the 3D printer heats a wet filament, it releases water vapor. The vapor messes with the structure of the material and the nozzle that releases the molten material, causing it to ‘hiss’ or make popping sounds. 

Some of the adverse effects of wet filaments are: 

  • Disturbing the Mechanical Structure. When you do 3D printing, you generally use filaments of certain materials that give you the desired results. Moisture in filaments adversely affects the mechanical parameters of the filaments, thus, producing rough products. 
  • Layer Separation. The moisture in filaments may affect the capability of the layers to join to create the final object. This happens when each layer becomes laminated and cannot join with the other layers. 
  • Foaming. After printing, the structure of the final object may bloat due to too much moisture in the pores. This bloating affects the density and the dimensional accuracy of the printed structure. 

Microwaving Different Types of Filaments

It is essential to select the right filament for the right job. Since there are many varieties and colors, you must consider cost, durability, and melting temperature.

Filaments are usually sold in weights from 0.5 to 2 kilograms (17.6 to 70 ounces), with thicknesses ranging from 1.75 to 3 millimeters (0.07 to 0.1 inches).

3D printing mainly uses thermoplastic filaments because they are easier to handle than metals or other materials. Here are some common filaments and their properties in case you want to dry them in a microwave: 

Acrylonitrile Butadiene Styrene (ABS)

Objects printed from ABS are durable and non-toxic. The material has a slightly higher melting point rendering it more flexible and easier to mold. 

The print temperature ranges from 210 to 250°C (410 to 482°F). Hence, the ideal drying temperature is 65°C (149°F) for approximately 3 hours. 

ABS is used in a closed frame printer. It is common to see that objects printed with ABS have a slight upward curl, especially the bottom corners, primarily due to a non-heated print bed on which the object is being printed. This is because when it gets exposed to moisture, it bloats. 

Polylactic Acid (PLA)

Being a plant-based biodegradable thermoplastic, PLA’s melting point is comparatively lower. The print temperature ranges between 180 and 230°C (356 to 446°F). The ideal drying temperature is 50°C (122°F) for approximately 3 hours. 

PLA is more rigid than ABS, and there is no warping, but it reacts differently than ABS when exposed to moisture. It changes its mechanical properties faster than any other material. It isn’t easy to use, leading to extruder jams in rare situations. 

Nylon

Developed in the 1930s, Nylon is an incredibly versatile synthetic material used almost everywhere, and recently it is also being used as a 3D printer filament. 

Nylon is like a polymer or plastic or a combination of different plastics. It is strong, durable, and flexible as it molds easily. It is one of the lowest-priced filaments in the market. 

It melts at 240°C (464°F). Thus, it is better to heat it at temperatures below 240°C (464°F). The average drying temperature is 70°C (158°F) for more than 12 hours. 

You should select 3D printers that can withstand such high temperatures. Like the ABS, objects printed with nylon filaments curl at the bottom, which can be mitigated using a heated print bed. 

Thermoplastic Elastomers (TPE)

TPEs are thermoplastics with high elasticity and are also recyclable. Objects printed with TPE are relatively more flexible due to the high elasticity of TPE.

The ideal drying temperature is 55°C (131°F), and the material needs to be dried for more than 4 hours.

Thermoplastic Polyurethane (TPU)

TPU is a type of thermoplastic elastomer with high durability and flexibility, just like TPE. TPU is more popular because the 3D objects that get printed are scratch-resistant. It has mechanical properties which render its characteristics between those of plastic and rubber. 

TPU is a strong filament that can be elongated and bear significant loads. The ideal drying temperature is 55°C (131°F) and is usually dried for more than 4 hours. 

High-Impact Polystyrene (HIPS)

HIPS is a low-cost, lightweight, and tough plastic. It is recommended as a second material with ABS or PLA in a dual-extruder printer which can be dissolved after printing. 

The ideal drying temperature is 60°C (140°F) for more than 4 hours. 

Polyvinyl Alcohol (PVA)

PVA is a synthetic polymer that is highly soluble in water. It is odorless, non-toxic, and biodegradable. Due to its low melting point, it can jam the extruder nozzle when overheated. 

It is often used as the second material in dual-extruder printers. The ideal drying temperature is 45°C (113°F) for more than 10 hours. 

Drying Filaments in Microwave vs. Other Options

Most people commonly use microwave ovens to dry filaments. As the filament is placed in the microwave oven, the moisture converts into steam and becomes thoroughly dried by the oven’s heat. 

This sounds very easy, but the main difficulty arises when you set the temperature. You must ensure that the temperature is suitable or adjusted according to the filament material so that it does not alter its mechanical properties, causing it to melt. 

A microwave oven is just one of the many options available to dry filaments. 

Some of the other options are: 

Vacuum Bag 

A vacuum bag is commonly used to dry filaments. The filament is placed in an oxygen-free vacuum box where the vacuum valve releases oxygen from the vacuum box. A vacuum gets created, which reduces the moisture content in the filament. 

Vacuum bags are known for their durability and reusability. They have recently made news due to the double-zip and triple-seal turbo valves with leak-proof technology for maximum air expulsion from the vacuum chamber. 

Desiccant

Desiccant is a substance usually found in a tight air pouch that dries filaments. The most popular substance used is silica. It has high absorption properties and is readily available. 

Silica pouches are used in many places, and you can easily collect them in a jar with holes on top. You can put this jar beside your filaments in a secure location, and that’s that. 

3D Filament Box

A specialized 3D filament box is also used to dry filaments by professionals who take drying seriously. It has been recently introduced and has both a heating and drying facility. You just have to set the correct temperature of the filament box. 

There is also a provision to set the drying duration. To avoid filament damage, it can also auto-adjust temperatures according to filament type, humidity, etc. 

It can simultaneously dry filaments and print 3D objects as well, because of which it is becoming increasingly popular. 

Dry Box

Dry Boxes or cabinets are properly sealed plastic boxes where you can dry your filament. Fortunately, you do not have to spend money on a specialized cabinet. You can easily make dry filaments on your own using readily available components. All you need is a large box that fits your spools, some sealing material, and some desiccant (for example, some silica gel). 

Watch the following tutorial to get some ideas on what you can do: 

Final Verdict: Which One Is the Best?

Out of all the options, the 3D filament box is the best since it has a specialized setting for heating and drying. This makes it incredibly easy and reliable. The other options apart from the microwave are also good because they don’t produce heat. Hence, the probability of the filament getting damaged is significantly less. 

An oven is suitable for plastic filaments like ASA and PET-G that are resistant to high temperatures. 

Therefore, the best source for drying filaments is subjective and would largely depend on what type of material you are using and how quickly you use them after purchase. 

SourceHeat producedBest for
Microwave OvenHeat is produced according to the set temperaturePlastic Filaments like ASA
Vacuum BagNo heatNylon
DesiccantNo heat High Weight filaments
3D Filament BoxAuto adjust with specialized temperatures for dryingAll types of filaments
Dry BoxNo heatAll types of filaments

Precautions To Take While Drying Filaments in the Microwave oven

Even though a microwave oven is hard to control, especially if you like using different materials, it is still useful. You don’t have to purchase anything, and unlike dry boxes or desiccants, you don’t have to wait for a long time. 

However, you have to be cautious when handling a microwave since damages are often irreversible. 

Here are some precautions you need to take: 

  • Set low temperatures. Set the temperature low so that the filaments get heated slowly and dry out without damaging or changing the mechanical properties of the filament. 
  • Use soaked rags. Soak some rags in a glass container and put them inside the microwave along with the filament. The moisture in the rags will use most of the heat to dry itself, leaving only a smaller portion of the heat to dry the moisture in the filament. This will slow the drying of the filament so that unnecessary damage is avoided. 
  • Add salt to the water. You can also add salt to the water used to soak the rags as it increases the conductivity—the more wet rags with salt you put, the faster the filament heats. 
  • Monitor the Drying Process. Keep checking the filaments to see if they are OK. If you have set low temperatures, then return every half an hour to check if the filament has dried. The surface of the filament should be warm and intact. 

Final Takeaway

For excellent 3D printing results, the filament needs to be dry. Wet filaments damage the polymer structure causing irreversible defects to the final product. 

A microwave oven is a common way of drying the filament at the appropriate temperatures. It eliminates any moisture that the filament could have absorbed. 

While other options like a desiccant or a dry box are risk-free, microwaves can cause adverse effects. But they are incredibly effective and do the job much faster. 

You can safely use a microwave oven to dry your filaments by taking proper precautions depending on the material, temperature, and time.