Why is Your 3D Printer Filament Brittle?

Brittle filament is a problem that can happen to anyone. One of the first spools I purchased ended up becoming very brittle and constantly broke when I tried to print.

Why is your 3D Printer filament brittle? Filament can become brittle from absorbing excess moisture. It can also be more prone to breaking if it is in a cold room.

After learning what to do about this issue, I quickly made some changes. I’ve never had the issue of brittle filament since.

Filament absorbs moisture

The first 3D printer I owned was stored in my garage. The garage is the one area that doesn’t receive climate control from the rest of the house.

Naturally, this brought forth a whole host of issues. The filament spools I first bought were kept on a long table next to the printer.

Over time, I began to notice a difference in filament quality. The PLA would snap very easily, and sometimes the extrusion was inconsistent.

After a little bit of research, I found that PLA (and also ABS) can absorb moisture into itself if it is left in the open air for too long.

The garage made it an even bigger problem, as opening the door allowed the humidity to creep in. I found a bunch of solutions for what to do if your filament is brittle, and also how to prevent it in the first place.

Removing moisture

The number one tip for removing moisture is to cook your filament. I was obviously a little concerned about baking my filament in an oven for a few hours, but this little action can make a huge difference in brittle filament.

For PLA, use a temperature of about 45 degrees Celcius (113 degrees Fahrenheit). For ABS, use a temperature of 80 degrees Celcius (176 degrees Fahrenheit). These temperatures are obviously much lower than the melting points of these plastics.

Just a word of warning though, place your filament into the oven after it has finished warming up. I have read that ovens can fluctuate in temperatures until they reach their target heat. Adding this extra step can be a good precaution in keeping your filament safe.

You definitely shouldn’t bake them at higher temperatures than these listed here, as it can result in your filament sticking together or becoming extremely warped. It is just enough heat to burn out the moisture.

The longer the filament stays in the oven, the more dry it’ll become. If your filament becomes brittle and has weird extrusion lines, then this is the best solution for you.

Another possible method of ridding moisture is a food dehydrator. I don’t own a dehydrator however, so I haven’t tried it. I would assume it works though, so its worth looking into.

Of course the best option would be for this to never happen in the first place, and I know the perfect way to do this.

Proper filament storage

If the filament were not sitting in the open, the moisture couldn’t creep in in the first place. There are several different storage methods that help keep your filament in optimal condition.

The first is to store the filament in an airtight ziplock bag. I stress the word airtight because otherwise none of these solutions would work.

If you have any large ziplock bags laying around, put your filament inside them when they aren’t being used. Always keep the packs of silica gel that the spool comes with, and place those inside your storage device.

The silica gel will absorb any moisture before your filament is able to. Leaving just a single one of those in a bag of filament will work extremely well.

If you don’t have any large bags, just use an airtight storage bin or cabinet. In my case, I have both a bin and cabinet full of filaments, with as much silica gel that I could find thrown in there.

These have eliminated all of my brittle filament problems, and I’m never going back to leaving my filament in the open.

The last big question about this is, “How do I keep the filament I’m currently using safe?” Most people’s issue comes about from the filament that’s already hooked up to the printer.

The solution: take out your filament every time your’e done with it. Yes, this is a big pain, but it’s definitely worth it to protect your filament.

If you live in an extremely humid area, you might want to invest in some wall-mounted filament holders. These airtight containers have a tube that extends outward and into the printer.

Personally I have never used one, as putting the filament away works for me. If the issue still persists, look into buying some spool holders.

Temperature difference

As your filament gets older, more heat will be needed to melt it. Moisture inside the filament also increases the need for more heat.

If the filament isn’t hot enough, it won’t be able to come out, leading to a clicking extruder and snapped filament.

Slowly increase the temperature of your hot end until filament flows freely. A temperature tower from Thingiverse would also be a massive help, and would save you a lot of time.

Cold environment

I live in an area that gets very cold in the winter. The garage I work in lets the cold in very easily.

The first winter with my printer was brutal. I had to warm the bed up with a heat gun any time I wanted to use it, and filament was extremely brittle.

Countless times I would go check on a print, only to find that the filament had snapped. Even after the print was complete, the print would be just as brittle.

The way I fixed this was to create an insulated box. It was a pretty simple design, just some MDF board with insulated walls. It was a pain to make however, so you might want to consider buying one online.

Of course the easiest option would be to move it to a warmer room, but for some that might not be an option.

Spool location

Some people get very creative with the way they mount their filament. For me, it’s mounted inside the enclosure I made for it.

If the filament is mounted in such a way that it’s bending, it’s bound to snap at some point. Even if it is not brittle from moisture, PLA is a naturally brittle plastic.

Be careful not to create any kinks in the filament. Even a small kink could make it snap. If a section of plastic has a bend in it, it would probably be best to snip it off.

That does waste a bit of filament, but it just might save you a lot of wasted time. Don’t go overboard with this though, as you may end up wasting too much.

If you are using a filament holder that came with your printer, then you shouldn’t be having this issue. You might want to rethink your layout if you have a custom spool holder.

Tangled Filament

Sometimes the filament can get tangled inside itself. It’s not always immediately noticeable, but it will always result in a failure.

Depending of your mounting solution, you may find that your entire spool has been pulled close to your printer. If not, it’ll just snap off.

If you have found your filament broken only once, it may not have been brittle in the first place. Just make sure there aren’t any tangles before printing.

If it’s a major tangle, you may have to keep unraveling your spool until you find the tangled section.

Filament quality

The quality of the filament will have a huge impact on the quality of your prints. If you buy a low quality filament, it can be much more brittle than a decent quality filament.

Try to stick to the major filament brands with proven track records. It’s always good to experiment with different brands, but some aren’t worth using. If you find that your filament snaps easily right out of the box, then consider changing brands

Jay Simmons

Jay Simmons is the main writer for The 3D Bros. He has several years experience working with 3D printers, and is the the co-owner of Cubold Manufacturing, LLC.

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