Posted by Vaughn [162.158.166.247] on Monday, May 23, 2022 at 19:14:26 :
In Reply to: rust removal posted by Todd Miller [172.70.211.50] on Monday, May 23, 2022 at 13:54:10 :
The black coating is Sodium Carbonate. You probably used tap water from a hose. You have to use de-ionized water to prevent the build up of Black Carbonate. Once the black carbonate dries, such as in your picture, it's next to impossible to get off. The part has to remain wet when you start to clean it. That's why I don't use electrolysis to de-rust parts.