Used caustic soda - safe disposal?

[averagebiker]

Hi all,
I have a couple if frames with stuck seat posts that are resisting my attempts to shift them without dissolving them. So that is my next likely move.
What do I do with the caustic soda once it has dissolved my seat posts away?
Cheers Rich.

 

[Dr Dremel]

I´ve diluted the solution (massively) and just disposed it in the toilet. After all it´s the main active component of drain cleaner. You can also neutralize it with acetic acid, but there´s math involved to get the concentration right.