[Healeys] Parkerizing

[Charlie Frazer]

I'm experimenting with Parkerizing, a process similar to Curt Arndt' s  
chemical bluing process for coloring and protecting steel parts from  
rust.
Parkerizing turns steel to a dark gray/black color in a solution of  
phosphoric acid and manganese at a temp of about 200 degrees to create  
a rust-protective coating.

Is there any reason to think this would make hardened suspension  
fasteners brittle?
Thanks for your thoughts,
Charlie