Ultimate Guide: The Best, Most Cost-Efficient And Simple Methods To Keep 3d Printer Filament Dry

Guide: Why and how to store your 3d printer filaments

This guide first begs the question, “Why should you even care to keep your 3D Printer filament dry?” ‘It’s not even wet’ you might be thinking! Or is it?

Ever had this happen…?

A print is going just fine, you’re 15 hours in, everything is looking great and suddenly it all starts to unravel. The print distorts, stops bonding to the previous layer and you’ve got a real mess on your hands. You furrow your brow and check your 3D printer settings and output files growing more and more anxious each second.

Is it the printer, or is it something else?

It’s very likely the problem is with your 3D printer’s filament and humidity.

Why 3D Printers, Filaments & Humidity are a problem

3D filaments fail due to moisture
Failed prints can be the result of moisture laden filaments and improper storage

You see, a humid filament can cause prints to fail partially or completely without much notice. If you’d had this happen, you know the frustration!

Leaving your filament spools lying around will make it attract molecules of water in the air; this is a filament’s inherent property called “hygroscopy”. This isn’t isolated to cheap 3d printers. Nor are high quality 3d printers immune to the problem. Any filament is subject to these conditions.

Scientifically speaking, the filament absorbs water molecules while being exposed to air within as little as 18 hours. Special filaments such as PVA are even worse at staying dry as they are more hygroscopic- it is imperative that they be kept in special containers or boxes to ensure a longer lifespan. Other filaments such as ABS and PLA are less hygroscopic to a degree, but that doesn’t mean you don’t need to protect them.

How does humidity damage the filament?

It does so in a number of ways

3D Printer filament failure due to moisture
Different filament failures due to moisture present. Nylon filaments shown here. Source
  • Augmentation of diameter (common with Bowden-tube printers)
  • Increased brittleness
  • Degradation
  • Breakage
  • Bubbling and hissing

These are not at all ideal conditions for your filament to be in, as a saturated 3D printer filament will need a higher temp to extrude properly. The severity also depends on the 3D printing filament’s quality. Nylon is more prone to humidity and can cause numerous issues such as unsightly bubbles, while PET isn’t affected by moisture as much as the more sensitive ones.

People who have experienced this problem try to create their own storage method- they keep filaments in special containers or use special driers. The issue is that these methods can be expensive, time-consuming or simply have a low cost/benefit ratio.

Print-While-Stored Filament Storage Solutions

The Maker, an avid 3D printing community lists some ways on how to properly store your 3D printing filament that allow for printing while in storage. Of course it’s ideal if you’re filament is already dry when you place it in the box to begin with. More on that later.

Some community derived solutions:

These are all great concepts and might work for you if you have really high humidity and filaments can get saturated in a number of hours + you need to them to be accessible for printing (e.g. not locked away). Plus they’re a little challenging to put together which is always fun! You can also adapt Jeremie Francois’ idea for a snazzy zero carbon footprint drier box, but you will need an environment with lots of sunshine, and lots of time to spend. Maybe a skylight with mirrors?

Simple Long-Term Filament Storage Solution

We have a simple solution for long term storage. How about a tested, hassle-free and cost-efficient way to keep your 3D printer filaments dry? The solution we provide makes it easy for you to identify the filament you need at the moment, while utilizing humidity absorbents that can last a long time. Interested?

Grab any vacuum bags you have at home or buy some if you don’t happen to have any. These bags are characterized by having one-way vacuum valves that you can use any standard vacuum cleaner to suck out all the air inside. The lady of the house might be using these to store clothes and fabric and are great space savers for pillows and blankets too. Vacuum bags protect your things from dust, mildew, pests and especially, humidity. Before you place your filament into a bag for storage use a filament clip to help prevent unraveling.

A few filament clip ideas

NOTE: Some vacuum bags labeled for traveling require you to roll them to remove the air. These aren’t ideal as it’s difficult to fully evacuate the air with something like filament inside the bag. It’s best to buy vacuum bags with double zipper lines because they can keep the vacuum better for longer as compared to one-zipper bags.

Vacuum bag long term filament storage
How 3D Printing Beginners sets up their vacuum bags with Silica Gel ready to vacuum out the air.

Vacuum bag buying tips:

  • Economy bags are okay such as this is a economy product that includes 15 bags and cost approximately $30 or 23EUR.
  • If budget allows, buy a more premium product. The valves are better, they seal better and the plastic is more durable.
  • Bags that are 50 by 60 centimeters, or 19 to 23 inches are best, but the size depends on your overall preference.
  • Be sure to look for transparent bags so you can see which 3D printer filament and color is in each bag without taking it out of storage.
  • Of course you’ll want to prevent future headaches by tagging and labeling your vacuum bags clearly.

Information to put on each bag:

  • Filament Brand
  • Filament size
  • Filament type
  • Date put in storage
  • Approximate amount left on the spool

Once you’ve packed up the filaments, vacuumed out all the air and labeled each bag they’re easily stored in a closet or stacked on top of each other.

Fully evacuated vacuum bag with 3d printer filament and silica gel
This bag was done by 3D Printing Beginners very nicely!

It’s pretty obvious why this works so well over other more complex solutions. A fully evacuated bag won’t have any ambient air, so the filament wouldn’t absorb any moisture as there isn’t any available.

You could stop here and you’d be miles ahead of keeping your filaments lying around exposed to ambient moisture. However there’s another step you could take to amply your effort to eliminate all possibilities of moisture getting in as well as monitor the status of your filaments. That’s where silica gel comes in!

Using Silica beads to remove and monitor moisture levels

Silica gel bead bags
Tyvek wrapped silica gel bags aren’t the best as you can’t see the gel beads and monitor moisture levels

These moisture absorbers are great against lingering humidity and it’s painless to add a few to each vacuum bag. Not all silica gel beads are equal though. The most common ones such as for shoes and jewelry storage come in small Tyvek (breathable) bags which prevents you from seeing to what degree the beads are saturated with moisture. A side benefit is silica beads can be gently dried in an low temperature oven and reused. More on that in a moment.

Silica used to dry out filament in storage
You could add silica straight to a box, but it might not be the most effective solution due to the amount of air left in the box reducing the effectiveness. Source

To get the maximum drying AND monitoring ability we recommend using silica bead packs with a moisture saturation indicator. These synthetic, amorphous and highly absorbent gels come with an indicator that changes color depending on the ambient moisture level. The color starts orange or yellow, then changes to blue or green as the beads acquire ambient air moisture. The blue indicator warns you whenever the beads come in contact with water, which in your case shouldn’t really ever happen. If it does, dry them before using them!

A word of caution- there are many kinds of silica gel moisture indicators out in the market. Protect your investment by choosing only premium indicators and don’t buy the cheap ones. Don’t buy the ones where the colors change from dark blue to pink (shown above), as they have cobalt chloride which is a carcinogenic ingredient, harmful to humans and considered in some parts of the world as a hazardous material. Use the color indicators that start out at orange and turn to green- these are relatively safer.

If silica works, is rice a good substitute?

In case you’re thinking of using rice as an alternative, here are a few things to consider. Rice, by itself, has hygroscopic properties, is cheap and very easy to acquire. Rice would be better than no desiccant at all, but we wouldn’t recommend it as an alternative to a proper silica gel, as silica gel beads are far superior in keeping humidity at bay. Rice at best is a weak or a mild desiccant, while silica gels are strong desiccants. Some of you may have tried the “drowned-smart-phone-in-a-bag-of-rice” trick before with mediocre results.

If you would really like to protect your 3D printer filaments, then use the best option available. Losing expensive filament or worse yet a project after hours of printing is a good enough reason to use a quality desiccant.

How to store the silica gel in the bag

3d printed Desiccant box
Simple printable desiccant box from Thingiverse

Choose an appropriate-sized, transparent container that has some small holes or incisions to allow any available air to pass through. The silica gel pack will eliminate all the remaining moisture in the vacuum bag, therefore making the environment as conducive as possible for your 3D printing filaments. You can even have fun with this and 3d print a jar/container for your beads.

Alternative Container ideas

If you don’t have an appropriate container laying around and this desiccant box doesn’t suit your fancy can just grab a regular plastic container that has a screw slid. Choices include slightly soft-walled 50mL Polypropylene holders, commonly used in storage and for keeping coins and screws in one place. They can be bought in online shops such as eBay or Amazon. Small plastic jars with lids or caps can work as well with a little modification. Use a 2mm (1/10″) wood drill bit and add some holes to the jars for the silica gel beads to work their magic. Fill in the beads and admire your handiwork, because you now have your very own moisture absorption system, complete with a water saturation indicator.

When And How To Reuse Your Silica Gel Beads

Silica gel moisture indicator beads
Beads turn from orange to blue as they absorb moisture Source

You will know when it’s time to dry your beads in an oven when the color changes from regular orange to somewhat of a greener hue. Carefully remove them from the vessel and lay them out flat in a baking tray. Put them in the oven and turn it on to 120C (250F) for around 3 hours. It would be safer to pop them in the oven even if the beads are microwaveable. The beads’ color should turn back to orange, indicating a very dry state. Put them back into the container and you are done.

The Three Hygroscopic States of Silica Gel

Indicator silica gel beads turn into various shades of hue depending on the amount of moisture they have. Quick reference on colors:

  • yellow (relatively dry)
  • green (fairly wet)
  • blue (has water)

Keep in mind that it only turns blue if totally submerged, so stop when you see green and replace them immediately.

First steps to make storage easier

If you have kept your filament spools unprotected for quite some time, then it is safe to say that they have already acquired moisture. Should you wish to devote as little time in keeping your silica beads as possible, then you should dry it in an oven first. Be careful in setting the oven temperature, and don’t put them in the containers immediately, as they can become sticky or soft, and the strands may even start to fuse together. Be patient and don’t fiddle with the drying time or the oven temperature.

Oven curing is not a one-stop, one solution for all filament types. Remember when we said that 3D printer filaments are made of different materials? A convection oven is good for starters. It is fan-assisted, so the air is evenly distributed inside. The heat should be set to low, or very low. PLA and its glass-transition temperature properties state that it starts to soften, melt or become rubbery as soon as you turn up the heat to around 60C (140F). Needless to say, PLA is out when it comes to oven curing. Also, don’t cure your filament for more than an hour. Let the silica gel beads take care of eliminating any remaining air moisture. Best to not take too much risk.

Drying settings to use for different filament types

Drying filament in a convection oven
Drying filaments in a convection oven is best as the fans move air around giving a much more even drying outcome. Source

Do your filaments a favor and check the corresponding glass transition temperature for your specific type of filament. ABS should be around 100C, Polycarbonate at around 150C, Taulman’s T-Glase is somewhere at 78C, and so on. Read up and brush on filament specs before considering drying them in an oven. The information we present here is strictly for informational purposes and you should take your time until you get experienced with this process.

Sometimes a filament can have a sharp end, especially if you have just taken them out of the heat chamber or the Bowden-tube. We know how spiky ends and plastic don’t mix well together, so try using filament clips (you can print them out) to secure the end of the spool. Keeps the risk of puncturing the vacuum bag to a minimum.

Filament Storage Tips from the Community

Litmus strips
Litmus strips can be used as moisture indicators if silica gel is hard to come by in your area
  • For some folks a color-change desiccant is hard to acquire. Alternatively use litmus strips as indicators to know the humidity in a given filament bag / box.
  • One silica gel regenerating technique is to lay them out in a shallow pan, then heating it to 250F for around 4 hours. Be sure to set an alarm and check back often to ensure all is well. Thanks to William for this ingenious idea!
  • You can also make use of food saver bags and a handy, portable vacuum device for the storage trick. These bags take slightly more complex to use and aren’t as reusable as they require a special sealing machine. These bags come in one continuous roll, and can easily be found in grocery stores. Cut a bag from the roll, use heat sealing to close off one end, then vacuum the air out of the other side. Recommended sizes are the wider bag rolls so that you won’t have any size issues. The bigger vacuum machines are advised to cut back on vacuum time. If you don’t already have the machine to seal these bags you may want to just go with vacuum bags as mentioned earlier. Thanks to Ian Wippell for this useful information!
  • Oven curing your 3D printer filament is tricky. Try this- for PLA filaments, set the oven to around 50C (120F), then cure for half an hour. Do a test print and see if bubbles form, or if hissing occurs. If so, do the same procedure for another half an hour. ABS should be around 90C (200F), with the same half-hour curing. Thanks to Bluemax for this helpful input!




Other filament storage conversations and resources


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