On Nov 12, 2:53*pm, Han wrote:

I surmise that drain cleaners darken wood because of their very high pH.
*Be careful with lye etc. *At high pH your skin and other proteins are
dissolved quite effectively, and the lye wil keep eating away until it
is either exhausted or really rinsed away. *Acids are bad for you too,
but at least they denature the protein and form something of a
protective layer; lye just dissolves everything.

Reason bases feel slippery is they react with skin oils to form soap.