<p>Polypropylene should be good, and relatively easy to print. <a href="https://www.google.com/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=&amp;ved=2ahUKEwj-ifvwhcTzAhVHgVwKHcLzAz0QFnoECAYQAw&amp;url=https%3A%2F%2Fwww.prinsco.com%2Fwp-content%2Fuploads%2F2017%2F06%2FHP-Chemical-Resistance-Tech-Note.pdf&amp;usg=AOvVaw2vqcOu6QGmqj7i6EnkaorC" rel="nofollow noreferrer">Prinsco</a> rate its resistance to NaOH as A-Excellent.</p>
<p>Ultimaker provide a <a href="https://ultimaker.com/learn/chemical-resistant-materials-a-beginners-guide" rel="nofollow noreferrer">useful guide</a> to the chemical resistance properties of 3D printing filaments.</p>

CC BY-SA 4.0
2021-10-12T06:04:21.527Z
Looks interesting my only concern is that it looks semi-flexible and may not be-able to print the M8 threads
Rick T
CC BY-SA 4.0
2021-10-12T06:40:23.937Z
@RickT [3DInsider](https://3dinsider.com/polypropylene-filament/) give a good run-down on PP filament. It looks like you can forget about it being "relatively easy" to print, though. My mistake. Nylon is another possibility, but its chemical resistance will not be as good as PP.
Mick
CC BY-SA 4.0
2021-10-12T17:25:52.980Z
Semi-flexible tends to only be flexible when the material is thin.  At that thickness material that isn't flexible tends to break.
Perry Webb
CC BY-SA 4.0
2021-10-12T17:51:29.140Z
PETG should work.  It appears you are using electrolysis of a NaOH solution to generate hydrogen and oxygen.  It will start getting soft at 100 °C.  Looking at your design it wouldn't be very flexible.  If you made a beaker with 1 mm walls, the walls would tend to be flexible.  2 mm+ walls would tend to be rigid.  Think of water bottle material.
Perry Webb
CC BY-SA 4.0
2021-10-12T18:44:31.160Z
@PerryWebb PETG "should work" `in my physical tests PETG does not work in the generator (I already tried)`.  The adapters break down after 2 or 3 days..  Also the liquid doesn't get hot, it only increases 5-10 degrees warmer than room temperature.    I'm looking into Polypropylene and the different blend types like @Mick said
Rick T
CC BY-SA 4.0
2021-10-12T19:17:20.487Z
Is the degradation only the adapters, and is it all the adapters?
Perry Webb
CC BY-SA 4.0
2021-10-14T02:03:30.587Z
@PerryWebb Yes, any thing made in PETG.(which are the adapters and top cap break down).  I just finished a test with some of the adapters soaking using PETG in the 1% NaOH solution for a week and no break down.   But it breaks down when running electrolysis with the same 1% NaOH solution after a day or two...Now I see why I didn't go into chemistry and stuck to programming hahah.  ;-)    I'm thinking the combination of H2 and O2 may be reacting with the PETG in some strange plastic Hydrogen embrittlement way.  I'm getting these same cracks...https://en.wikipedia.org/wiki/Hydrogen_embrittlement
Rick T
CC BY-SA 4.0
2021-10-14T02:12:07.103Z
Also...https://cdn.intechopen.com/pdfs/39405/InTech-Degradation_and_recyclability_of_poly_ethylene_terephthalate_.pdf
Rick T
CC BY-SA 4.0
2021-10-14T08:52:33.027Z
Any chance the electrodes are getting hot.
Perry Webb
CC BY-SA 4.0
2021-10-14T19:17:50.663Z
@PerryWebb I plan on ordering a thermocouple to have a better way of monitoring the temperature, but I've ordered PP to at-least get me going again.
Rick T
CC BY-SA 4.0
2021-10-14T19:25:57.363Z
To use a thermocouple you will probably need one that goes with a hand-held meter, at least one that floats, that is not plugged into an AC outlet.  It's easier to use an optical pyrometer; same principle as the thermometers used to measure temperature pointed to the forehead or in the ear.
Perry Webb
CC BY-SA 4.0
2021-10-12T04:38:57.873Z
2021-10-12T04:38:57.873Z
Mick
<p>I'm testing a HHO generator (oxyhydrogen - browns gas generator) and I use 1% NaOH solution (sodium hydroxide -lye).  I made some <strong>M8 threaded adapters</strong> for it using PETG (Polyethylene terephthalate glycol) which works for storage.  But I notice the <strong>M8 threaded adapters starting to disintegrate</strong> when the generator is running.  Does anyone know of a low cost filament that will work with a HHO generator (oxyhydrogen - browns gas generator) and a 1% NaOH solution (sodium hydroxide -lye).</p>
<ol>
<li>I'm not using glass in the main generator</li>
<li>I'm using 2 bubblers for safety with flashback arrestor.</li>
<li>The printer I have access to is a Prusa Mk3s FDM</li>
<li>The HHO generator doesn't use more than 2 amps to generate HHO so the device is cool to the touch (not much heat is generated)</li>
</ol>
<p>This is what some of the M8 PETG adapters look like.</p>
<p><a href="https://i.sstatic.net/dOuJJ.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/dOuJJ.jpg" alt="img1" /></a></p>
<p><a href="https://pawplus.wordpress.com/3d-designs-page-2/" rel="nofollow noreferrer">https://pawplus.wordpress.com/3d-designs-page-2/</a></p>
<p>Thanks</p>

CC BY-SA 4.0
2021-10-12T11:06:34.673Z
Worth noting that sodium hydroxide will etch *glass*.
Zeiss Ikon
<filament><material><filament-choice><filament-quality>
Looking for 3D filament thats compatiable with HHO-oxyhydrogen and NaOH sodium hydroxide -lye
Rick T
# Looking for 3D filament thats compatiable with HHO-oxyhydrogen and NaOH sodium hydroxide -lye

(Asked by: username_0 on 2021-10-12)

I'm testing a HHO generator (oxyhydrogen - browns gas generator) and I use 1% NaOH solution (sodium hydroxide -lye). I made some **M8 threaded adapters** for it using PETG (Polyethylene terephthalate glycol) which works for storage. But I notice the **M8 threaded adapters starting to disintegrate** when the generator is running. Does anyone know of a low cost filament that will work with a HHO generator (oxyhydrogen - browns gas generator) and a 1% NaOH solution (sodium hydroxide -lye).

1. I'm not using glass in the main generator
2. I'm using 2 bubblers for safety with flashback arrestor.
3. The printer I have access to is a Prusa Mk3s FDM
4. The HHO generator doesn't use more than 2 amps to generate HHO so the device is cool to the touch (not much heat is generated)

This is what some of the M8 PETG adapters look like.

[![img1](https://i.sstatic.net/dOuJJ.jpg)](https://i.sstatic.net/dOuJJ.jpg)

<https://pawplus.wordpress.com/3d-designs-page-2/>

Thanks

**Tags:** filament, material, filament-choice, filament-quality
> **Comments:**
> **username_1**: Worth noting that sodium hydroxide will etch *glass*.  

---

## 1 answers

### Answer by username_2 on 2021-10-12. Score: 2

Polypropylene should be good, and relatively easy to print. [Prinsco](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj-ifvwhcTzAhVHgVwKHcLzAz0QFnoECAYQAw&url=https%3A%2F%2Fwww.prinsco.com%2Fwp-content%2Fuploads%2F2017%2F06%2FHP-Chemical-Resistance-Tech-Note.pdf&usg=AOvVaw2vqcOu6QGmqj7i6EnkaorC) rate its resistance to NaOH as A-Excellent.

Ultimaker provide a [useful guide](https://ultimaker.com/learn/chemical-resistant-materials-a-beginners-guide) to the chemical resistance properties of 3D printing filaments.

> **Comments:**
> **username_0**: Looks interesting my only concern is that it looks semi-flexible and may not be-able to print the M8 threads  
> **username_2**: @RickT [3DInsider](https://3dinsider.com/polypropylene-filament/) give a good run-down on PP filament. It looks like you can forget about it being "relatively easy" to print, though. My mistake. Nylon is another possibility, but its chemical resistance will not be as good as PP.  
> **username_3**: Semi-flexible tends to only be flexible when the material is thin.  At that thickness material that isn't flexible tends to break.  
> **username_3**: PETG should work.  It appears you are using electrolysis of a NaOH solution to generate hydrogen and oxygen.  It will start getting soft at 100 °C.  Looking at your design it wouldn't be very flexible.  If you made a beaker with 1 mm walls, the walls would tend to be flexible.  2 mm+ walls would tend to be rigid.  Think of water bottle material.  
> **username_0**: @PerryWebb PETG "should work" `in my physical tests PETG does not work in the generator (I already tried)`.  The adapters break down after 2 or 3 days..  Also the liquid doesn't get hot, it only increases 5-10 degrees warmer than room temperature.    I'm looking into Polypropylene and the different blend types like @Mick said  
> **username_3**: Is the degradation only the adapters, and is it all the adapters?  
> **username_0**: @PerryWebb Yes, any thing made in PETG.(which are the adapters and top cap break down).  I just finished a test with some of the adapters soaking using PETG in the 1% NaOH solution for a week and no break down.   But it breaks down when running electrolysis with the same 1% NaOH solution after a day or two...Now I see why I didn't go into chemistry and stuck to programming hahah.  ;-)    I'm thinking the combination of H2 and O2 may be reacting with the PETG in some strange plastic Hydrogen embrittlement way.  I'm getting these same cracks...https://en.wikipedia.org/wiki/Hydrogen_embrittlement  
> **username_0**: Also...https://cdn.intechopen.com/pdfs/39405/InTech-Degradation_and_recyclability_of_poly_ethylene_terephthalate_.pdf  
> **username_3**: Any chance the electrodes are getting hot.  
> **username_0**: @PerryWebb I plan on ordering a thermocouple to have a better way of monitoring the temperature, but I've ordered PP to at-least get me going again.  
> **username_3**: To use a thermocouple you will probably need one that goes with a hand-held meter, at least one that floats, that is not plugged into an AC outlet.  It's easier to use an optical pyrometer; same principle as the thermometers used to measure temperature pointed to the forehead or in the ear.  

---

