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

Ignoramus32654 wrote:
On Sun, 01 Jan 2006 15:05:39 -0800, Grant Erwin wrote:

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.


You were 100% right. I did what you suggested. No more rust, but the
surface is dull grey. I was kind of hoping that it would become shiny,
like newly ground/sawed iron. Any way to get to this point? What is
that grey coating?

It isn't really a coating, it's just the bare steel. It isn't shiny because the
surface has microscopic irregularities which reflect the light randomly. The
only way to get it shiny is to polish it, i.e. mechanically remove the surface
irregularities, and this can be a lot of trouble. If the part is precision
machined going in, it may come out shiny, but if it's like a tie plate, which
has never been shiny in all its life, you can't get there from here.

GWE

For info on this process try
http://users.moscow.com/oiseming/rustdemo/rustdemo.htm.

On Sun, 01 Jan 2006 23:23:45 GMT, Ignoramus32654
wrote:


You were 100% right. I did what you suggested. No more rust, but the
surface is dull grey. I was kind of hoping that it would become shiny,
like newly ground/sawed iron. Any way to get to this point? What is
that grey coating?


The grey isn't a coating, it's the iron/steel surface with the pitting from
where the rust was. I quite like the finish but if you really want to get a
shiny finish you'll have to resort to old fashioned polishing methods.


Mark Rand
RTFM

"Ignoramus32654" wrote in
message ...
On Mon, 02 Jan 2006 01:34:46 +0000, Mark Rand
wrote:
On Sun, 01 Jan 2006 23:23:45 GMT, Ignoramus32654
wrote:


You were 100% right. I did what you suggested. No more rust, but
the
surface is dull grey. I was kind of hoping that it would become
shiny,
like newly ground/sawed iron. Any way to get to this point? What
is
that grey coating?


The grey isn't a coating, it's the iron/steel surface with the
pitting from
where the rust was. I quite like the finish but if you really want
to get a
shiny finish you'll have to resort to old fashioned polishing
methods.

Nope. The dark dull grey stuff was black oxide. I removed it by
running a wire brish very briefly. (less than 1 minute). Now the
surface is very pitted, but actually reflective. I will post photos
soon.

i


Ig,

The wire brush is polishing the steel which as Mark says is grey due
to the surface texture at a microscopic level. The wire brush is
changing that texture by smearing the highs into the lows.

AWEM

"Andrew Mawson" wrote in message
...

The wire brush is polishing the steel which as Mark says is grey due
to the surface texture at a microscopic level. The wire brush is
changing that texture by smearing the highs into the lows.

The black stuff definitely is a distinct compound that's left on the surface
after the process, it's fairly loose, and you can see it when you brush it
off.

Someone online, who seemed to know his electrochemistry, described it like
this: The electrolytic derusting process is not like plating or reverse
plating. Rather, it reduces Fe2O3 (red iron oxide) to some compound that I
forget, and converts some of the rest into Fe3O4, which is black iron oxide.

I don't know enough about it to know for sure, but that fits exactly with
the experience I've had with it, in terms of appearance and behavior, and
I've done it quite a lot.

--
Ed Huntress

On 1 Jan 2006 17:08:15 -0800, "flyfisher" wrote:

For info on this process try
http://users.moscow.com/oiseming/rustdemo/rustdemo.htm.

"The tin in brass will etch out of the surface"

" Passivate the surface [afterwards]"

"The yellow is caused by the presence of chromate. Hexavalent chromium
is poisonous. "

Yeah, that's a credible source 8-(

Andy Dingley wrote:
On 1 Jan 2006 17:08:15 -0800, "flyfisher" wrote:


For info on this process try
http://users.moscow.com/oiseming/rustdemo/rustdemo.htm.


"The tin in brass will etch out of the surface"

" Passivate the surface [afterwards]"

"The yellow is caused by the presence of chromate. Hexavalent chromium
is poisonous. "

Yeah, that's a credible source 8-(

I would suggest the Russians know a bit about rust.
Have you seen recent pictures of what was once the Soviet Navy?

According to Rex B "":
Andy Dingley wrote:
On 1 Jan 2006 17:08:15 -0800, "flyfisher" wrote:


For info on this process try
http://users.moscow.com/oiseming/rustdemo/rustdemo.htm.

[ ... ]

Yeah, that's a credible source 8-(

I would suggest the Russians know a bit about rust.
Have you seen recent pictures of what was once the Soviet Navy?

You're jumping to conclusions. A quick whois on "moscow.com"
produces the following (in part)


================================================== ====================
First Step Internet
PO Box 9587
Moscow, ID 83843
US

Domain Name: MOSCOW.COM
================================================== ====================

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Wed, 04 Jan 2006 01:10:41 +0000, with neither quill nor qualm,
(DoN. Nichols) quickly quoth:

According to Rex B "":
Andy Dingley wrote:
On 1 Jan 2006 17:08:15 -0800, "flyfisher" wrote:
For info on this process try
http://users.moscow.com/oiseming/rustdemo/rustdemo.htm.
Yeah, that's a credible source 8-(
I would suggest the Russians know a bit about rust.
Have you seen recent pictures of what was once the Soviet Navy?

You're jumping to conclusions. A quick whois on "moscow.com"
produces the following (in part)


Moscow, ID 83843

Oh, I thought it was about electronic cattle. My bad.


--
If you turn the United States on its side,
everything loose will fall to California.
--Frank Lloyd Wright