Filament Moisture Guide: Which Filament Absorbs Water? How to Fix It


3D printer filament has a tendency to absorb moisture and water over time from the immediate environment. Some filament is definitely worse than others, so I decided to write an article detailing which filament absorbs water, as well as how to prevent moisture from being absorbed.

The main 3D printer filament that absorbs moisture and water is PLA, Nylon, and PVA. These filaments are known as hygroscopic, which means they absorb moisture from the environment. Depending on the humidity, the filament can quickly be rendered unusable until the moisture is removed.

Luckily, there are ways to prevent hygroscopic filament absorbing water so keep reading to find out, as well as a quick guide to which filament absorbs water.

Which Filaments Absorbs Moisture?

  • PLA
  • Nylon
  • PVA
  • ABS

In 3D printing, moisture can be troublesome for our print quality due to absorption of the moisture and water within the surrounding environment. You won’t be able to see the effects of this until your 3D print quality is coming out poorly.

Pretty much all filament experiences moisture absorption in some ways but some filaments absorb water worse than others.

PVA filament is one of the top filaments in the hygroscopic category and this filament should be kept in a well-sealed box or the protective bag that usually comes with the filament.

PLA is widely used in 3D printing applications and is a fairly hygroscopic filament. The organic material used in its production is considered as the basic reason behind its moisture absorption property.

Nylon filament comes just after the PLA. Nylon is a strong filament and can resist heat and impact efficiently but absorbing moisture can be said as its drawback. Many users do talk about how quickly Nylon absorbs moisture.

ABS filament also falls in the hygroscopic category, it means that you have to follow precautionary measures to protect it from absorbing moisture and ruining all the quality and clarity of your 3D prints.

Does PLA Absorb Water?

PLA does absorb water and can cause printing problems. Most of the time when you use PLA that has moisture, it will extrude from the nozzle causing bubbles that can damage your print and its smoothness.

PLA can absorb water quickly from the atmosphere as it is one of those materials that are very sensitive in terms of tracing water content. You want to make sure your PLA is fairly protected, especially in a humid environment.

In dryer environments, PLA does pretty well even if you leave it on your spool holder. I myself leave my PLA on my 3D printer and haven’t yet run into problems, but I do keep a good amount of ventilation going.

What Happens When PLA Absorbs Moisture?

When PLA absorbs water it tends to become weak and this weakness depends on the amount of moisture in it.

  • When PLA absorbs moisture it usually gets swollen and using such a filament in the 3D printer can cause the blockage of the hot end. There are possibilities that it may ruin the hot end to the extent that you have to replace it.
  • The print may not stick to the print bed perfectly and will cause warping.
  • The filament can cause steam and bubbles when heated and this will disturb the flow of filament from the nozzle and your print will have a rough or spotty finish.
  • The resultant print may be noticeable weaker and a bit of force can easily break it.

How Do I Know if My Filament Has Absorbed Moisture

There are a few ways to identify whether your filament has absorbed moisture:

  • Unusually rough textures and imperfections such as blobs or stringing
  • Extrusion lines are uneven
  • Part strength is weaker than usual and layer adhesion poor
  • Cracking, popping sounds when heated up by the hotend
  • Filament on spool is more brittle and has less flex

If you identify one of these symptoms or a combination of them, you’re going to want to dry your filament, especially if it is a known hygroscopic filament as mentioned above.

It’s fairly easy to dry filament which is explained in this article below.

Does PLA Need to be Kept Dry?

It is a good idea to keep your PLA filament as dry as possible to get the best 3D printing experience.

Not just PLA, but every filament that absorbs moisture should be kept dry because moisture can cause plenty of problems. It can cause the filament to break down while extruding from the nozzle.

I wrote an article about why PLA gets weak and brittle, and moisture is definitely one of many reasons.

Moisture in the filament is considered as one of the basic reasons that cause clogging of extruder assembly and nozzle.

Some experts have suggested that PLA should be kept in an airproof box that can protect it from moisture especially if you are working in a humid environment.

No matter if a filament is hygroscopic or non-hygroscopic, it is recommended to store them in a dry box to assure better quality and printing experience. It just adds to that aspect of high quality, and also protects filament from dust build-up.

Which Filament is Non-Hygroscopic?

Almost all types of filaments that are used in 3D printing are hygroscopic and absorb water, but we cannot deny the fact that some filaments are better than the others in this regard.

Most of the 3D printing experts and filament manufacturers claim that HIPS is near to the non-hygroscopic property as it falls in the bottom of the filaments list that absorbs water.

HIPS should be stored properly but there are probably fewer chances that moisture can damage this filament completely.

It is mostly used to support other printing materials but can also be used as a primary printing material.

How Should I Store My Filament to Prevent Absorbing Moisture

You should store your filament in an airtight container with desiccants, which absorb the moisture in the air. People usually place desiccants in closets, drawers and wardrobes to keep their clothes and personal items protected from moisture.

You can get yourself a perfect sized Storage Container from Amazon. Some people get one large container, while others get a few smaller ones to hold each spool of filament.

It’s a good idea to also use these desiccants to keep your filament dry.

I’d recommend getting the Dry & Dry Premium Silica Gel Packets from Amazon for a great price. They are widely popular and work really well for all your moisture-absorbing needs.

Another great option to store your 3D printer filament is to use vacuum-sealed bags such as the AirBaker Vacuum Storage Bags, which is highly rated and well-loved by thousands of current users of the product.

It has a solid 4.3/5.0 rating on Amazon (at time of writing) and continues to deliver amazing quality and an airtight seal around important products at your desire.

How to Dry PLA, ABS Nylon & Other Filament?

As moisture is a common and frustrating problem in 3D printing, manufacturers and experts have come up with a lot of solutions that can help you to not only fix this problem but will also help you to prevent it from occurring in the future. The most effective ways to remove moisture from filament includes:

  • Filament Dryers
  • Oven and Food Dehydrators

Filament Dryers

When it comes to drying the filaments, you should have the best suitable devices to get the job done. Filament dryers are the most efficient and effective devices that are specifically designed to remove moisture from the filament and make it ready for you to be used.

  • Simply put the filament in the device and after a specific time, your filament will be cured.
  • Most of the modern 3D printers include a built-in filament dryer which is a great feature as it will allow you to focus on your prints instead of filament moisture problems.

The premium option here that I would recommend has to be the SUNLU Upgraded Filament Dryer Box from Amazon. With the item beside you, say goodbye to wet 3D printing filament.

  • Can dry filament and print at the same time
  • Easy temperature settings adjustments according to filament type, humidity etc.
  • Manually set your drying times (the usual is 3-6 hours)
  • Compatible with most 3D printer filament out there
  • Ultra quiet so it doesn’t disturb your environment
  • Comes with a cool 2-inch LCD monitor to display temperature and time

You can really improve your print quality for many years to come with a product like this. If you plan to be 3D printing for long into the future, the SUNLU Filament Dryer Box is a great thing to have.

Ovens and Food Dehydrators

This is considered a simple solution to dry filament, but keep in mind that if your oven cannot hold the calibrated temperature accurately, then using an oven can be risky.

You just have to take care of some factors and you will get the job done properly.

Make sure you test your oven temperature beforehand so you know it is accurately emitting the temperature that you set. Small differences in oven temperature can ruin your filament spool so keep this in mind.

Food dehydrators are probably a better option to dry filament because they are able to operate at a relatively low temperature which makes it less risky as compared to common ovens.

  • Set the oven at a temperature that is less than the glass transition temperature of the filament you have to dry.
  • The ideal temperature for PLA is about 40-45°C while this range is from 65-80°C for strong filaments such as ABS and Nylon.
  • Some ovens can start with a boost of temperature and that is why it will be wise to place the filament in the oven after it reaches the required temperature.

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