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.




  • $\begingroup$ Worth noting that sodium hydroxide will etch glass. $\endgroup$
    – Zeiss Ikon
    Commented Oct 12, 2021 at 11:06

1 Answer 1


Polypropylene should be good, and relatively easy to print. Prinsco rate its resistance to NaOH as A-Excellent.

Ultimaker provide a useful guide to the chemical resistance properties of 3D printing filaments.

  • $\begingroup$ Looks interesting my only concern is that it looks semi-flexible and may not be-able to print the M8 threads $\endgroup$
    – Rick T
    Commented Oct 12, 2021 at 6:04
  • $\begingroup$ @RickT 3DInsider 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. $\endgroup$
    – Mick
    Commented Oct 12, 2021 at 6:40
  • $\begingroup$ Semi-flexible tends to only be flexible when the material is thin. At that thickness material that isn't flexible tends to break. $\endgroup$
    – Perry Webb
    Commented Oct 12, 2021 at 17:25
  • $\begingroup$ 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. $\endgroup$
    – Perry Webb
    Commented Oct 12, 2021 at 17:51
  • $\begingroup$ @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 $\endgroup$
    – Rick T
    Commented Oct 12, 2021 at 18:44

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