<p>PETG sticks to brass nozzles <em>really well</em>. Better than it sticks to itself, in many cases. When travelling over already-printed material, especially if the filament is not retracted (Cura calls this kind of travel &quot;combing&quot;) or if the material it's travelling over is overextruded and bulging up, the nozzle will pick-up/dig-up some of that material and drag it around. There, it accumulates until the size and shape is adequate to cause it to get dislodged when a part that's sticking out far enough not to be molten collides with another part of the print, and it falls off. It may get picked up again by the hot nozzle later, leading the process to repeat.</p>
<p>There are various mitigations for this:</p>
<ul>
<li><p>Limit &quot;combing&quot;. In Cura, set &quot;Max Combing Distance Without Retract&quot; to 1 mm and &quot;Connect Infill Lines&quot; on to get good behavior without introducing huge numbers of retractions. slic3r-based slicers have an option called something like &quot;Only Retract When Crossing Perimeters&quot; that you want to turn <strong>off</strong> to get the same effect.</p>
</li>
<li><p>Make sure you're not overextruding. Turn down flow slightly if needed.</p>
</li>
<li><p>Dry your filament. PETG is always wet unless you dried it in the past 24 hours yourself, and wet PETG does this a lot worse.</p>
</li>
<li><p>You may be able to select a nozzle that the material doesn't stick to. There are non-stick (likely PTFE) coated nozzles designed for this purpose (but they can't be used at high temperatures), and nickel plated seems to do better too. I'm not sure about other materials like stainless steel or (note: expensive) tungsten carbide but they may be options to improve this too.</p>
</li>
</ul>

CC BY-SA 4.0
2022-10-03T15:01:15.583Z
2022-10-03T15:01:15.583Z
R.. GitHub STOP HELPING ICE
<h1>Stringing</h1>
<p>PETG is prone to stringing, even with the best settings. Often, I live with some stringing as strings are easy to clean up while other issues can be introduced by getting totally rid of it.</p>

CC BY-SA 4.0
2022-10-03T14:50:54.467Z
It's not clear to me that this is stringing at all. In my book, "stringing" means material that's pulled out of the nozzle by surface tension during travel moves (usually outside the model, but internal stringing is a thing too). The model in OP's pic however does not have any external travel moves. It looks more like this is material that got torn up by travel across it ("combing" travel tends to do this with PETG), possibly as a result of overextrusion too.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-10-02T14:15:23.197Z
2022-10-02T14:15:23.197Z
Trish
<p>I am printing Eryone 1.75 mm PET on my Kobra Max printer with 80°C bed and 230°C.</p>
<p>I am experiencing this:</p>
<p><a href="https://i.sstatic.net/RXv0n.jpg" rel="nofollow noreferrer" title="Possible stringing and over-extrusion"><img src="https://i.sstatic.net/RXv0n.jpg" alt="Possible stringing and over-extrusion" title="Possible stringing and over-extrusion" /></a></p>
<p>Is this &quot;over-extrusion&quot; and &quot;stringing&quot;?</p>
<p>And how do I avoid this?</p>

CC BY-SA 4.0
2022-09-26T04:57:08.853Z
I think it's neither. I was not able to find Eryone PET but PETG. Printing this with 195°C would lead to what you have there. I recommend printing it hotter. About 230°C like the manual says.
Kev Inski
CC BY-SA 4.0
2022-09-26T06:53:13.247Z
PETG has a tendency or be prone to stringing more often than other filaments. You need to print the filament in the window of the listed temperatures and setup the printer correctly, have your retraction in order, but still if all is tuned sometimes PETG will string, e.g. my black PETG doesn't string at all, while the white from the same vendor will string very little with the same settings.
0scar
CC BY-SA 4.0
2022-09-27T07:37:05.173Z
You could try printing two separate retraction towers to figure out the exact retraction parameters for your printer and material, One for velocity, the other for distance.
Piotrekdoro
CC BY-SA 4.0
2022-09-27T10:32:07.270Z
@KevInski Thank you, I accidentally posted the wrong nozzle temperature. I do use 230°C.
tmighty
CC BY-SA 4.0
2022-09-27T10:32:45.763Z
@0scar May I ask you which black PETG you use?
tmighty
CC BY-SA 4.0
2022-09-27T14:24:55.017Z
@tmighty ColorFabb PETG Economy
0scar
<print-material>
What is this behaviour called and how do I fix this?
tmighty
# What is this behaviour called and how do I fix this?

(Asked by: username_0 on 2022-09-25)

I am printing Eryone 1.75 mm PET on my Kobra Max printer with 80°C bed and 230°C.

I am experiencing this:

[![Possible stringing and over-extrusion](https://i.sstatic.net/RXv0n.jpg "Possible stringing and over-extrusion")](https://i.sstatic.net/RXv0n.jpg "Possible stringing and over-extrusion")

Is this "over-extrusion" and "stringing"?

And how do I avoid this?

**Tags:** print-material

> **Comments:**
> **username_1**: I think it's neither. I was not able to find Eryone PET but PETG. Printing this with 195°C would lead to what you have there. I recommend printing it hotter. About 230°C like the manual says.  
> **username_2**: PETG has a tendency or be prone to stringing more often than other filaments. You need to print the filament in the window of the listed temperatures and setup the printer correctly, have your retraction in order, but still if all is tuned sometimes PETG will string, e.g. my black PETG doesn't string at all, while the white from the same vendor will string very little with the same settings.  
> **username_3**: You could try printing two separate retraction towers to figure out the exact retraction parameters for your printer and material, One for velocity, the other for distance.  
> **username_0**: @username_1 Thank you, I accidentally posted the wrong nozzle temperature. I do use 230°C.  
> **username_0**: @username_2 May I ask you which black PETG you use?  
> **username_2**: @username_0 ColorFabb PETG Economy  

---

## 2 answers

### Answer by username_4 on 2022-10-03. Score: 1

PETG sticks to brass nozzles *really well*. Better than it sticks to itself, in many cases. When travelling over already-printed material, especially if the filament is not retracted (Cura calls this kind of travel "combing") or if the material it's travelling over is overextruded and bulging up, the nozzle will pick-up/dig-up some of that material and drag it around. There, it accumulates until the size and shape is adequate to cause it to get dislodged when a part that's sticking out far enough not to be molten collides with another part of the print, and it falls off. It may get picked up again by the hot nozzle later, leading the process to repeat.

There are various mitigations for this:

* Limit "combing". In Cura, set "Max Combing Distance Without Retract" to 1 mm and "Connect Infill Lines" on to get good behavior without introducing huge numbers of retractions. slic3r-based slicers have an option called something like "Only Retract When Crossing Perimeters" that you want to turn **off** to get the same effect.
* Make sure you're not overextruding. Turn down flow slightly if needed.
* Dry your filament. PETG is always wet unless you dried it in the past 24 hours yourself, and wet PETG does this a lot worse.
* You may be able to select a nozzle that the material doesn't stick to. There are non-stick (likely PTFE) coated nozzles designed for this purpose (but they can't be used at high temperatures), and nickel plated seems to do better too. I'm not sure about other materials like stainless steel or (note: expensive) tungsten carbide but they may be options to improve this too.


---

### Answer by username_5 on 2022-10-02. Score: 0

# Stringing

PETG is prone to stringing, even with the best settings. Often, I live with some stringing as strings are easy to clean up while other issues can be introduced by getting totally rid of it.

> **Comments:**
> **username_4**: It's not clear to me that this is stringing at all. In my book, "stringing" means material that's pulled out of the nozzle by surface tension during travel moves (usually outside the model, but internal stringing is a thing too). The model in OP's pic however does not have any external travel moves. It looks more like this is material that got torn up by travel across it ("combing" travel tends to do this with PETG), possibly as a result of overextrusion too.  

---

