XPost: alt.home.repair   
   From: bowman@montana.com   
      
   On Fri, 21 Apr 2023 13:28:15 +0900, Minoru Osaka wrote:   
      
   > I ran an experiment on an old rusty pair of shears left outside too   
   > long.   
   > The phosphoric acid turned the metal from pure rust to black   
   > "something".   
   > I don't know what that "something" is, but it's black, whatever it is.   
      
   That's a phosphate coating that helps retard rust.   
      
   https://en.wikipedia.org/wiki/Iron(III)_phosphate   
      
   Had you used hydrochloric acid it would have also removed the rust but   
   after you washed it off an left the shears to dry they would almost   
   immediately been covered with rust.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)