"Mark Rand" wrote in message
...
On Sat, 14 Feb 2004 20:44:15 GMT, "Ed Huntress"
wrote:


From my reading about the process (and I know little about
electrochemistry
myself), it appears there is no erosion of metal involved at all, on
either
side. That's why I question the idea that stainless causes a problem.

Ed Huntress


I have used stainless because I have some sheet which is about the right
size.
I have neither seen or measured any loss from the stainless anode although
it
is very obvious (from current variations) that one must run with reverse
polarity regularly to de-polarize the anode. I imagine that carbon would
not
suffer from this problem???

I don't know, Mark. The people who seem to know what they're talking about
on this subject describe it as a very weak action, which won't even affect
black rust (Fe3O4). It only works on red rust. The weak alkaline solution
doesn't produce any significant quantity of ionized metal ions. It doesn't
do much of anything, in fact, except strip red rust somehow.

The black grunge that remains on the part is mostly black rust. It comes off
easily with a light brushing from a stainless brush. In a couple of cases
I've used hydrochloric acid to remove the black rust, and then put the part
back in the electrolytic process in the hope that it will remove any
chloride ions picked up from the acid.

I don't know. But I have a lot of de-rusted parts to show that it does a
good job.

Ed Huntress