<p>I'm having the exact same problem - it is enough to leave the filament inside the PTFE tube for an overnight and the next day the filament inside the tube is so brittle that I'm not even able to eject the filament without disconnecting the tube and getting out all small pieces of filament manually... but from my experience, it affects only cheap PLA filaments (like Creality ST-PLA) - I never had such issue with other types of filaments (ASA, PETG) or higher-quality brands of PLA (e.g Fillamentum, Filament PM...).</p>
<p>BTW - there is a video on YouTube demonstrating the same issue: <div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/SvpSxHLotMI?start=0"></iframe>
            </div></div></p>

CC BY-SA 4.0
2021-11-27T16:18:57.443Z
Hi Dominik and welcome to SE.3D Printing. SE websites are driven by questions and answers, your answer is more a forum style "Me too" comment to another question where you ask for help to start a discussion. This is not what the answer section should be used for. Please read the [help], accessible through the button with the question mark at the top right menu. Please take the [about] and also have a look at the questions and answers to understand how SE works.
Greenonline
CC BY-SA 4.0
2021-11-27T16:26:49.267Z
Apologies for the standard comment above. However, your post doesn't really answer the question, and will probably end up being deleted. You could post answer question, and refer back to this question using the URL - however, as you say, you have the exact same issue, so it would end up being closed as a duplicate - unless you add why the proposed solution (in the other - partially incomplete - answer) didn't work. Or a place a bounty on the question.
Greenonline
CC BY-SA 4.0
2021-11-27T09:31:47.573Z
2021-11-27T09:53:50.160Z
2021-11-27T09:53:50.160Z
Dominik Palo
<p>I have this exact problem as well. I am feeding filament from the dry box through the tube into the top of the hot end. After approximately 2 days I would notice that the filament is broken somewhere close to the hot end. I don't believe that it's just humidity.</p>
<p>I suspect that the filament being brittle and being made to conform to the PTFE tube's shape, having been recently on a spool, is causing the breaks.</p>
<p>As a result, I'm going to write a small script that will heat the hot end and eject 200 mm of filament every so often.</p>
<p>EDIT: Whilst the script works, the filament would just break somewhere else lower down in the tube. Therefore the amount of filament that would need to be extruded periodically would be just wasteful. A better solution would be to unload the filament, either manually or automatically (somehow).</p>

CC BY-SA 4.0
2021-07-27T11:37:43.600Z
I don't have a dry box. The filament in the open air doen;t get brittle, wile the one in the PTFE tube does ...
Nicu Surdu
CC BY-SA 4.0
2021-11-27T16:23:54.200Z
Did your script work? If so, can you post it in the answer..?
Greenonline
CC BY-SA 4.0
2021-11-29T14:53:08.940Z
@Greenonline, no because the filament would just break somewhere else further down in the tube. It's not a practical solution. I suspect that I would have to have some sort of "unload" mechanism, to retract the filament into the dry box.
user77232
CC BY-SA 4.0
2021-11-29T15:00:14.650Z
That's a shame. Thanks for the update though :-) However, does that mean that your answer isn't really a solution (apart from your suspicion of the brittle filament)..? BTW, could you [edit] your answer and add that last bit of info in your comment to it? Thanks.
Greenonline
CC BY-SA 4.0
2021-07-23T14:33:02.140Z
2021-11-29T15:28:34.760Z
2021-11-29T15:28:34.760Z
user77232
<p>I know that it's said the PLA becomes brittle when kept in a humid environment, but my case is slightly weirder:</p>
<p>I have rolls of 1.75 mm PLA that I bought years ago and they are fine. But if I leave my spool fed inside the PTFE (Teflon) tube of my 3D printer, that part that is inside the PTFE tube, and only that part, gets brittle. The filament spool is always (even when stored) in open air.</p>
<p>Is it still the humidity that somehow is better kept inside the tube, or is there a weird reaction of PLA with PTFE?</p>

CC BY-SA 4.0
2021-07-23T14:28:15.187Z
I have this exact problem, and mine is in a dry box.
user77232
CC BY-SA 4.0
2021-07-27T11:38:57.313Z
I don't have a dry box. Filament spool is always (even when stored) in open air.
Nicu Surdu
CC BY-SA 4.0
2023-04-30T17:03:42.400Z
I have the exact same problem with a PLA roll that is 3 years old. Breaks in the PTFE tube, but only if it has beend inside the tube for 1-2 days, the rest of the rest of the roll prints just fine. Any update on this?
Stiefel
<pla><print-material><ptfe-tube>
PLA filament becomes brittle inside PTFE tube
Nicu Surdu
# PLA filament becomes brittle inside PTFE tube

(Asked by: username_0 on 2021-07-19)

I know that it's said the PLA becomes brittle when kept in a humid environment, but my case is slightly weirder:

I have rolls of 1.75 mm PLA that I bought years ago and they are fine. But if I leave my spool fed inside the PTFE (Teflon) tube of my 3D printer, that part that is inside the PTFE tube, and only that part, gets brittle. The filament spool is always (even when stored) in open air.

Is it still the humidity that somehow is better kept inside the tube, or is there a weird reaction of PLA with PTFE?

**Tags:** pla, print-material, ptfe-tube

> **Comments:**
> **username_1**: I have this exact problem, and mine is in a dry box.  
> **username_0**: I don't have a dry box. Filament spool is always (even when stored) in open air.  
> **username_2**: I have the exact same problem with a PLA roll that is 3 years old. Breaks in the PTFE tube, but only if it has beend inside the tube for 1-2 days, the rest of the rest of the roll prints just fine. Any update on this?  

---

## 2 answers

### Answer by username_3 on 2021-11-27. Score: 1

I'm having the exact same problem - it is enough to leave the filament inside the PTFE tube for an overnight and the next day the filament inside the tube is so brittle that I'm not even able to eject the filament without disconnecting the tube and getting out all small pieces of filament manually... but from my experience, it affects only cheap PLA filaments (like Creality ST-PLA) - I never had such issue with other types of filaments (ASA, PETG) or higher-quality brands of PLA (e.g Fillamentum, Filament PM...).

BTW - there is a video on YouTube demonstrating the same issue:

> **Comments:**
> **username_4**: Hi username_3 and welcome to SE.3D Printing. SE websites are driven by questions and answers, your answer is more a forum style "Me too" comment to another question where you ask for help to start a discussion. This is not what the answer section should be used for. Please read the [help], accessible through the button with the question mark at the top right menu. Please take the [about] and also have a look at the questions and answers to understand how SE works.  
> **username_4**: Apologies for the standard comment above. However, your post doesn't really answer the question, and will probably end up being deleted. You could post answer question, and refer back to this question using the URL - however, as you say, you have the exact same issue, so it would end up being closed as a duplicate - unless you add why the proposed solution (in the other - partially incomplete - answer) didn't work. Or a place a bounty on the question.  

---

### Answer by username_1 on 2021-07-23. Score: 1

I have this exact problem as well. I am feeding filament from the dry box through the tube into the top of the hot end. After approximately 2 days I would notice that the filament is broken somewhere close to the hot end. I don't believe that it's just humidity.

I suspect that the filament being brittle and being made to conform to the PTFE tube's shape, having been recently on a spool, is causing the breaks.

As a result, I'm going to write a small script that will heat the hot end and eject 200 mm of filament every so often.

EDIT: Whilst the script works, the filament would just break somewhere else lower down in the tube. Therefore the amount of filament that would need to be extruded periodically would be just wasteful. A better solution would be to unload the filament, either manually or automatically (somehow).

> **Comments:**
> **username_0**: I don't have a dry box. The filament in the open air doen;t get brittle, wile the one in the PTFE tube does ...  
> **username_4**: Did your script work? If so, can you post it in the answer..?  
> **username_1**: @username_4, no because the filament would just break somewhere else further down in the tube. It's not a practical solution. I suspect that I would have to have some sort of "unload" mechanism, to retract the filament into the dry box.  
> **username_4**: That's a shame. Thanks for the update though :-) However, does that mean that your answer isn't really a solution (apart from your suspicion of the brittle filament)..? BTW, could you [edit] your answer and add that last bit of info in your comment to it? Thanks.  

---

