Igor, the black smut is normal. Try running lukewarm water over the part in a
utility sink and rubbing on it with a 3M pad, the part should turn a nice matte
gray. Of course, a tie plate will most likely be pitted, no problem.

GWE

Ignoramus32654 wrote:
I made a basic electrolytic derusting setup and am using my welder

http://igor.chudov.com/projects/Weld...berTig-Welder/

to run the current.

I am derusting a very rusty old railroad tie plate that spent a while
laying in my yard.

After a while of derusting at about 15 amps, 37 volts or so, the
surface of it turned black.

Should I expect it to become shiny metal after a while, by itself, or
is it my responsibility to clean off the black crud?

Could it be that I am basically done with derusting and simply need
to clean the black crud with a wire brush or some such?

I am taking pictures as I go.

thanks

i