I had similar experience while following this prescription.
I was trying to black anodize some parts in the lab (helicopter
unrelated). I have not had more time allocated to pursue
this part of the project. A company in Philly did anodizing for
~$50 in about two days. It, however, still bothers me why
it did not work.
Best regards, Boggie
Dr. Boguslaw Gajdeczko
Engine Combustion Lab.