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The Importance of Dry Filament for 3D Printing

If your 3D printed projects are coming out rough, brittle, or discolored, you may not be storing your filament correctly. 3D printing filament is sensitive to the moisture in the air and needs to be kept in a dry area.

Two of the most common 3D printing filaments are Polylactic Acid (PLA), a polymer, and Acrylonitrile Butadiene Styrene (ABS), a copolymer. Just as monomers can be joined together to create these polymers, so can they be depolymerized.

One way that depolymerization occurs is through a process called hydrolysis. This is the fancy name for the process of water breaking down polymer chains. 3D printing filaments like PLA or ABS are so sensitive to this process that even the humidity in the air can compromise their quality. For some filament types, this process can occur in as little as 48 hours[i].

Hydrolysis can cause your projects to print with tiny bubbles left from evaporated water held in the filament[ii]. This will leave your projects looking rough or dull instead of glossy and shiny. This is because of the craters left on the outside from popped bubbles and evaporated water droplets.

Humidity can also weaken the filament. Projects become more brittle or pull apart more easily because moisture inside the filament evaporates when it passes through the extruder and that moisture leaves air pockets behind1.

Here’s an experiment that shows two of the same item printed with the same filament but one was dry and the other had been exposed to the humidity in the air:

wet and dry filament comparison

Image by Anton Mansson via AntonMansson.com

The dry filament printed with a smoother, glossier finish than the wet. The wet filament left behind broken strings and rough patches.

On top of a change in appearance after printing, humidity in the air can cause the filament to swell in size. This can cause problems during the printing process in relation to the extruder and print head and can even lead to filament jams[iii].

Keeping your filament dry should be a priority if you want to take care of your 3D printer and print the highest quality projects possible.

So, what can you do to keep your filament from being affected by the humidity? You have a few options.

One option is to dry your filament in an oven. If done right, this will restore your filament back to its original glory, but it can be a delicate process with potentially disastrous consequences (e.g. a puddle of filament in the bottom of your oven)3.

If you’re interested in that process, here are some general directions (please do your own research before trying this method):

  1. Preheat your oven to 70-80°C (160-180°F).
  2. Place spool in oven for 4-6 hours.
  3. Remove and place in airtight container with desiccant.1

Another option is to buy a filament dryer/container like PrintDry. It works similarly to a dehydrator and has a dial on the front to choose the temperature you’d like to dry the filament at. It will dry your filament out and can also act as a storage container to keep your filament dry.

Unfortunately, PrintDry can only store one or two spools of filament at a time and costs upwards of $100. You’ll be forced to either buy additional storage containers or store your spools in the open air and dry them every time you want to use them. PrintDry also does not have any tubing to protect filament as it dispenses, nor does it have any rubber seal at the filament dispense point. It is just a hole in the side of the container that is continually letting in new air.

More popular and cost-effective options involve airtight containers with desiccant. It is important to know that drying wet filament in this container can take a while. This product is better suited to protect new and unexposed filament or filament that has already been dried1,3.

The cheapest option here is a large plastic bag or vacuum-sealed bag with about 10 grams of desiccant. It will keep your filament dry and protect against dust but is not a long-term solution. Eventually, the bag will begin to let moisture through. It’s important to keep a close eye on the desiccant if you utilize this option2.

Another downside to the plastic bag is that you will have to open the bag every time you want to use the filament. This will let moisture back in the bag and leave your filament exposed while it is in use. It is best to minimize the time that the filament is in the open air.

A better option would be the 3D Printer Filament Box from Katamco. This is a slim, clear container designed to store, protect, and dispense filament. It costs significantly less than a filament dryer but still offers a long-term solution.

https://katamco.com/collections/3d-printing/products/3dfuse-brand-3d-printer-filament-box

This filament box is designed for ease of use. It’s clear so you can easily identify the filament you are looking for. There are filament exit ports to dispense the filament straight from the container. It has a hygrometer on the front so that you can monitor the temperature and humidity levels of the air inside the container. It comes with color-changing desiccant to absorb moisture and alert you when it needs to be recharged.

All of these design choices were made so that you will rarely have to open the container. The air inside the container will stay dry and the filament will have almost no exposure to the open air (especially with the 36” filament guide tube that comes with Katamco’s Filament Box).

The slim design of this box also allows you to keep multiple spools of filament organized while in storage or in use. The multiple filament exit ports allow you to dispense the filament from the front, top, or back of the box so that you can choose the port that suits your setup the best.

Keeping your filament dry is essential to creating quality projects. Protect your filament and protect the financial investment you’ve made in your 3D Printer setup. Wet filament can lead to wasted product and wasted money.

Regardless of the solution you pursue, you will be doing your future self a favor by protecting your filament.

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[i]Taylor Landry, https://www.matterhackers.com/news/filament-and-water

[ii] Tyler Koslow and Gauthier de Valensart, https://www.filaments.directory/en/blog/2016/09/15/what-effect-does-humidity-have-on-your-filamentby

[iii] Anton Olsen, https://geekdad.com/2015/06/3d-printing-tips-tricks/