We use a 6% potassium hydroxide (KOH) solution for electrolysis. This solution is known to be "slippery". Does this mean that it will leak/seep through NPT pipe threads more than plain water?

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    $\begingroup$ @JonCuster, it's not slippery becuase it removes oils, but because it saponifies the fats and oils, changing skin to soap. That is not at all good for tissues. Sorry if this comment sounds caustic. $\endgroup$ Sep 20 at 17:07
  • $\begingroup$ @DrMoishePippik - sigh, yes, you are correct. But because it is messing with those oils it is also ripping them out of the near surface layers... $\endgroup$
    – Jon Custer
    Sep 20 at 17:08

1 Answer 1


Potassium hydroxide ($\ce{KOH}$) makes skin feel slippery because it saponifies oils in your skin, changing them to soap. It is called caustic potash because of the damage it does to tissue.

However, though $\ce{KOH}$ is caustic to skin, it does not affect most metallic pipe or, at 6%, PTFE ("Teflon") tape dope, nor is it much more likely to leak out (it may lower surface tension somewhat, so leakage would be faster if there is a hole). It could cause leaks if there are any glass, aluminum, brass or other materials which it attacks. See this corrosion chart from Dixon.

BTW, PTFE does dissolve in potassium, and other alkali metals, in liquid ammonia, $\ce{NH3}$. See O. Lanzi, S. Godfrey answers.


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