Fragile filament

I have some filaments that are ‘fragile’ - in that they break randomly coming off of the spool.
They are PLA. I’ve had two prints fail tonight because the filament broke.
Is there any way to salvage these filaments, or should they just be ‘binned’?

Thanks for any suggestions!

They have adsorbed moisture from the air and need to be dried out. I use a cheap food dehydrator to do it.

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I’m drying them now…Give them overnight then try again!

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Yep 9.9/10 times wet filament is the culprit of that one.

In the case that it is not just let me know and we can see if something else is happening.

So far, I’ve dried the filament overnight.
When I tried it again, it broke within a few minutes.
I’ll try drying it for another day…

Apparently if pla has absorbed enough water to become brittle to the point of easily snapping; the water absorption has changed the filament at the molecular level (changes in its chemical structure and crystallinity) and it is too late to dry it - drying it will help, but it will remain somewhat brittle because of that fundamental molecular change to the pla.

Thanks, Filek!
It’s kind of what I expected - this filament came from the supplier brittle, and I was hoping I could still manage to use it. I bought it some time ago, and when it proved brittle, I just set it aside.

I’ll wait until tomorrow, when I’ll re-try printing after overnight drying (in a food dehydrator).
If that isn’t enough, I’ll bin it.

After drying overnight, they still broke. So they got binned.
Thanks for the help!

Thanks for reporting your findings - I was considering trying to dry some brittle filament for like 2 days straight to see if I could overcome the molecular changes, but I think that you have proven that it isn’t possible.

Hmm I have had PLA become brittle too. Personally I dried in in a filament dryer for one full cycle (I keep fresh desiccant in with it during the drying.) and found it to be far better. Usually the first few wraps are not awesome then the middle is fine. I would look at the drying method.

You said it - the first few wraps are not awesome - so even your expert drying techniques did not work and the middle of the role was likely just not wet enough to completely fail.

I too use desiccant in the dryer, I even added my own hydrometer to ensure it was keeping the humidity low in the dryer. The fact is that, according to the materials scientist, too much water absorption will forever change the molecular makeup of the PLA and drying it does not change it back.
So the trick is to dry it BEFORE it is too wet; the only time is was too wet for me was a sample of PLA sent with the printer and who knows how long that has been sitting.

I can’t tell you that, all I can say is it was open on a shelf since my Tiko died in 2017, I think. Who needs sparkle cyan filament? It printed fine after drying. My basement is not very dry at the best of times.

A few tips, if you don’t live in Nevada keep filament in a sealed bag. It’s a pain but I never have had to toss a roll.

RH is a fickle measurement. It is a misleading. Relative humidity is relative to temperature. The RH will drop in a heated environment because it is heated, it has nothing to do with water evaporation.

Real example. My work room was 17.8ºC when I got up, Cold. RH was 43%. I turned on the heater and it is now up to 21ºC the RH dropped to 35.6. Good right?

The amount of water in the air is 6.5gm/m2 for both, the absolute humidity is constant. Warm air can hold more water. At -35ºC 100% RH and 1% RH are almost exactly the same the air cannot hold any water vapour.

This is why I use fresh desiccant every time and leave it in the dryer for 24 hours at a minimum. Measurements inside the dryer need to be converted.

I Always dry PC, and Nylon 100% of the time. PETG if it is open a while I will put a few feet in an old Monoprice and just extrude some if it pops into the dryer it goes. PLA gets a bend test and if it breaks in it goes.

My exact technique is when PLA breaks (I pull 4-5 feet off the roll and test there) I toss the first few wraps and loosen the roll up. I dry it for a couple of days. My current dryer is all automatic (daft thing really) a hex. I liked the Sunlu V1 better until it had an accident. (gravity)

I have not had issues with printing the old filament, ever. I don’t doubt there is a change, is it enough you can’t overcome? No.

I have bought rolls of filament that were brittle straight from the shipper. Some filament suppliers buy pellets and they sit out in huge boxes for an undisclosed length of time. The rolls ship brittle.

One of the reasons why new people, I always recommend starting with premium brands, like Prusa, or Polyalcomy. They control everything carefully. The tell is if the rolls are really neat, all aligned perfectly. It is rare for the filament out of the box to have any issues.

I don’t suggest always using crazy expensive filaments, once you get used to the printer it isn’t necessary. Low cost filament on occasion comes bad. Figuring out how to use it could be helpful especially when you have 10 or 15 rolls arrive all brittle.

Just trying to help.

No use flogging this, and my experience is the same as yours - almost ALL filament can be saved with a dryer.

But science is science, and hydrolysis is what happens when water is absorbed. Hydrolysis is the addition of water molecules into the polymer chains of your filament. As you add more and more water molecules, you interrupt more and more chains, making them smaller and smaller and the filament becomes very weak and brittle. In the end some filaments can become so weak and brittle, their chain lengths become too short and there is no saving them.

It has only ever happened once to me - a 10 meter sample sent with the printer that just would not dry out.

The article below explains it if you are curious.

There are many articles, I tend to distrust articles used as marketing.

Many articles like the linked one back these results. That said, submerging in water for a month will change a lot of materials, hardly practical.

Vapours, heat, water all change PLA. In your short sample it easily could have been effected by something else. PLA has low resistance to many acids, acetic, nitric, even citric and many solvents and alcohols. It is also possible that the filament was exposed to VOCs and these too cause the same kind of issues.

I have tried to use PLA around a handful of chemicals, acetic, and oxidizers and parts became brittle in days and crumble apart.

I personally have PLA parts outside for years, it is discoloured but not completely brittle, my soap dish, the first design I did has been used daily for 5 or 6 years it too is not more brittle then a newly printed one.

Personally I suspect PLA brittle filaments are not only water but something else too. Removing the first few wraps seems to resolve the issue for me.

If PLA became really brittle exposed to some water vapour in the air quickly. Parts made with it would be useless, this would be a huge issue and the industry would move away from it.

My experience I have never seen PLA degrade noticeably exposed to only water. Maybe your experience is different.

All good points, and thanks!
I would have liked to know the trick about discarding the first few layers - another thing to try before binning it.
But I felt that I couldn’t trust it, and, as it had been dried twice; I just chalked these up to just poor quality filament.
It’s the last time I’ll buy from that particular supplier!

It is hard to know.

There are a lot of variables, I have very old filament and the oldest I didn’t understand I needed to be fussy with it so it is in open rolls on a shelf in a shared studio.

It is possible it was dry inside but if it is that is a miracle as for years it was kept in 15gm/m3 when I shared a space with a snake breeder. It was wicked humid uncomfortably so. (87% @ 20ºC) in the open. It is all brittle but dries enough that I feel comfortable printing it and would not expect it to break in the extruder or filament path.

I now am fairly careful to keep it bagged. I don’t keep rolls open anymore. The bagging protects it from moisture and/or VOCs so it doesn’t matter what is effecting it now. It doesn’t sit around much these days I print close to a kg a day now.

Hmmm it isn’t really fair to name suppliers and it also isn’t fair to expect every roll to be a problem from one supplier.