I read Orrin's bit about using graphite electrodes for electrolytic derusting. I
saw some cheap on ebay and picked up some, maybe $10. The first ones arrived
smashed up, the second ones showed up intact. They're about 8" long, maybe
1/2x1" rectangular bar (very roughly). They look fragile. As I said, they were
over $5 apiece. They will probably work fine, although I often need an electrode
that is longer than that.

Today I was rooting around industrial South Seattle looking for a used but
usable welding ground clamp and I noticed these long perfectly round things that
looked just like graphite. I picked one up -- it's 12" long, 3/8" diameter,
looks pretty strong, looks real conductive. It's a scarfing electrode, first
unclad one I've seen, and it must be made of some sintered carbon. They had
hundreds and hundreds available for 35¢ each. Skeptical, I bought one. I just
hauled out my DVM and my pointy-sharp leads and probed in in ohmmeter mode. End
to end it's 2 ohms or less (my meter isn't accurate in that range) and it
appears to be just as conductive on the sides as on the ends. In short, it
appears to be a real good candidate for use as an electrolytic derusting electrode!

I'll test it and report. This would be great if it works like I hope it does, it
would mean electrodes that don't rust, no cruddy solution, without the huge
expense and fragility of graphite.

GWE

Since I'm gonna be in the area in another week or so,
where is that shop, and what other electro/mechano/nerd
junk stores are still in business?
/mark to the North


Grant Erwin wrote:
I read Orrin's bit about using graphite electrodes for electrolytic
derusting. I saw some cheap on ebay and picked up some, maybe $10. The
first ones arrived smashed up, the second ones showed up intact. They're
about 8" long, maybe 1/2x1" rectangular bar (very roughly). They look
fragile. As I said, they were over $5 apiece. They will probably work
fine, although I often need an electrode that is longer than that.

Today I was rooting around industrial South Seattle looking for a used
but usable welding ground clamp and I noticed these long perfectly round
things that looked just like graphite. I picked one up -- it's 12" long,
3/8" diameter, looks pretty strong, looks real conductive. It's a
scarfing electrode, first unclad one I've seen, and it must be made of
some sintered carbon. They had hundreds and hundreds available for 35¢
each. Skeptical, I bought one. I just hauled out my DVM and my
pointy-sharp leads and probed in in ohmmeter mode. End to end it's 2
ohms or less (my meter isn't accurate in that range) and it appears to
be just as conductive on the sides as on the ends. In short, it appears
to be a real good candidate for use as an electrolytic derusting electrode!

I'll test it and report. This would be great if it works like I hope it
does, it would mean electrodes that don't rust, no cruddy solution,
without the huge expense and fragility of graphite.

GWE

"Grant Erwin" wrote: (clip) They had hundreds and hundreds available for
35¢ each. Skeptical, I bought one. (clip)
^^^^^^^^^^^^^^
You bought ONE? That's almost like a guarantee that when you go back they
will be all gone, or the price will have gone way up. I would have made an
offer on all of them, and taken a chance. (That's why my garage is full to
overflowing with bargains like this.)

Mark wrote:

Since I'm gonna be in the area in another week or so,
where is that shop, and what other electro/mechano/nerd
junk stores are still in business?
/mark to the North

It isn't what you're thinking, not a junk store, although they do carry some
used stuff. Anyway, it's Pacific Industrial Supply Co. on 4th South in Seattle,
a couple of blocks north of Spokane Street. Wear ear plugs, their PA is LOUD.

Pacific Industrial Supply Co.
2960 4th South
Seattle, WA 98134
206-682-2100

They are *not* going to sell out of scarfing electrodes. Plain carbon arc
gouging electrodes are featured in many catalogs including Tweco's. That's the
whole point, if this concept proves out, anyone can get great EDR electrodes
easily and very cheaply.

GWE


Grant Erwin wrote:

I read Orrin's bit about using graphite electrodes for electrolytic
derusting. I saw some cheap on ebay and picked up some, maybe $10. The
first ones arrived smashed up, the second ones showed up intact.
They're about 8" long, maybe 1/2x1" rectangular bar (very roughly).
They look fragile. As I said, they were over $5 apiece. They will
probably work fine, although I often need an electrode that is longer
than that.

Today I was rooting around industrial South Seattle looking for a used
but usable welding ground clamp and I noticed these long perfectly
round things that looked just like graphite. I picked one up -- it's
12" long, 3/8" diameter, looks pretty strong, looks real conductive.
It's a scarfing electrode, first unclad one I've seen, and it must be
made of some sintered carbon. They had hundreds and hundreds available
for 35¢ each. Skeptical, I bought one. I just hauled out my DVM and my
pointy-sharp leads and probed in in ohmmeter mode. End to end it's 2
ohms or less (my meter isn't accurate in that range) and it appears to
be just as conductive on the sides as on the ends. In short, it
appears to be a real good candidate for use as an electrolytic
derusting electrode!

I'll test it and report. This would be great if it works like I hope
it does, it would mean electrodes that don't rust, no cruddy solution,
without the huge expense and fragility of graphite.

GWE

Graphite electrodes y'say? Heck, gouging rods work great, long as you don't
ask too much of them. (Electrolysis of salt solution (say to make a strong
oxidizer like sodium chlorate) easily wears down any graphite of course.)

You can remove the cladding by anodizing (heh) it in a salt solution until
the metal dissappears (leaving copper oxide floating in solution), then it's
free to use for whatever.

Industrial graphite works good too, I got three 1 1/2" square 18" long bars
from a surplus dealer on e-Bay for a total $30 with shipping. Came from
around your area, as a matter of fact.

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

"Grant Erwin" wrote in message
...
I read Orrin's bit about using graphite electrodes for electrolytic
derusting. I
saw some cheap on ebay and picked up some, maybe $10. The first ones
arrived
smashed up, the second ones showed up intact. They're about 8" long, maybe
1/2x1" rectangular bar (very roughly). They look fragile. As I said, they
were
over $5 apiece. They will probably work fine, although I often need an
electrode
that is longer than that.

Today I was rooting around industrial South Seattle looking for a used but
usable welding ground clamp and I noticed these long perfectly round
things that
looked just like graphite. I picked one up -- it's 12" long, 3/8"
diameter,
looks pretty strong, looks real conductive. It's a scarfing electrode,
first
unclad one I've seen, and it must be made of some sintered carbon. They
had
hundreds and hundreds available for 35¢ each. Skeptical, I bought one. I
just
hauled out my DVM and my pointy-sharp leads and probed in in ohmmeter
mode. End
to end it's 2 ohms or less (my meter isn't accurate in that range) and it
appears to be just as conductive on the sides as on the ends. In short, it
appears to be a real good candidate for use as an electrolytic derusting
electrode!

I'll test it and report. This would be great if it works like I hope it
does, it
would mean electrodes that don't rust, no cruddy solution, without the
huge
expense and fragility of graphite.

GWE

On Fri, 01 Jul 2005 18:42:32 -0700, Grant Erwin
wrote:


Today I was rooting around industrial South Seattle looking for a used but
usable welding ground clamp and I noticed these long perfectly round things that
looked just like graphite. I picked one up -- it's 12" long, 3/8" diameter,
looks pretty strong, looks real conductive.

Well done! I've been looking for graphite block electrodes on the right side
of the pond without much (any) success, but I can get 13mm...1/2" gouging
electrodes at £35/100. I can live with that price for something that works.

I'll be waiting for the test report.


Thanks for the idea.


Mark Rand
RTFM

On Fri, 01 Jul 2005 18:42:32 -0700, Grant Erwin
wrote:

I read Orrin's bit about using graphite electrodes for electrolytic derusting. I
saw some cheap on ebay and picked up some, maybe $10. The first ones arrived
smashed up, the second ones showed up intact. They're about 8" long, maybe
1/2x1" rectangular bar (very roughly). They look fragile. As I said, they were
over $5 apiece. They will probably work fine, although I often need an electrode
that is longer than that.

Today I was rooting around industrial South Seattle looking for a used but
usable welding ground clamp and I noticed these long perfectly round things that
looked just like graphite. I picked one up -- it's 12" long, 3/8" diameter,
looks pretty strong, looks real conductive. It's a scarfing electrode, first
unclad one I've seen, and it must be made of some sintered carbon. They had
hundreds and hundreds available for 35¢ each. Skeptical, I bought one. I just
hauled out my DVM and my pointy-sharp leads and probed in in ohmmeter mode. End
to end it's 2 ohms or less (my meter isn't accurate in that range) and it
appears to be just as conductive on the sides as on the ends. In short, it
appears to be a real good candidate for use as an electrolytic derusting electrode!

I'll test it and report. This would be great if it works like I hope it does, it
would mean electrodes that don't rust, no cruddy solution, without the huge
expense and fragility of graphite.

GWE

If you ever get around an electric arc furnace, ask for some
electrodes that have gotten too short to use. (There's a foundry near
Coeur d' Alene that uses an electric arc furnace.) Or, if you know
anyone who works at an aluminum smelter, ask them to pick up some
carbon for you. The pot lines use carbon electrodes.

The large dry-cell batteries used in crank telephones and Hot Shot
batteries have large (about 1-inch diameter) carbon electrodes in
them.

Another source of carbon is from decomissioned graphite-shielded or
graphite-moderated nuclear reactors. Don't laugh. I once had
hundreds of pounds of it; gave most of it away, though. (Yes, I did
have it checked for radioactive contamination.)

There's one bit of warning about using graphite or carbon, however.
Some kinds of binder appears to be affected by either the solution or
the electric potential.

I had a very embarrasing thing happen to me, once. I very generously
(so I thought) gave away--to a whole crowd of fellows--graphite plates
that I'd sawed (sawn?) from bigger blocks. Later, I used one of them
in my electrolytic vat. Much to my embarrassment, it disappeared
overnight. It turned to mush and fell to the bottom of the tank.
Apparently, the binder dissolved.

On the other hand, I've had some graphite electrodes last for over a
year of continuous duty in my electrolytic de-rusting setup.

I've gotten some good graphite deals on eBay. One needs to be
selective, however.

Orrin

I have never dealt with them but for some graphite items I buy
occasionally from other sources these guys prices look good and I may
get some items from them next, they do have a handing charge per order.

http://www.graphitestore.com/

Mark Rand wrote:

On Fri, 01 Jul 2005 18:42:32 -0700, Grant Erwin
wrote:


Today I was rooting around industrial South Seattle looking for a used but
usable welding ground clamp and I noticed these long perfectly round things that
looked just like graphite. I picked one up -- it's 12" long, 3/8" diameter,
looks pretty strong, looks real conductive.


Well done! I've been looking for graphite block electrodes on the right side
of the pond without much (any) success, but I can get 13mm...1/2" gouging
electrodes at £35/100. I can live with that price for something that works.

I'll be waiting for the test report.


Thanks for the idea.


Mark Rand
RTFM

What am I missing here? I use FREE electrodes that will last nearly forever
unless the polarity gets accidentally reversed. I find them along the road
disguised as stainless wheel covers. The current one is from a Buick. I
like it better than the Cadillac one it replaces.

George Willer

"Mark Rand" wrote in message
...
On Fri, 01 Jul 2005 18:42:32 -0700, Grant Erwin
wrote:


Today I was rooting around industrial South Seattle looking for a used but
usable welding ground clamp and I noticed these long perfectly round
things that
looked just like graphite. I picked one up -- it's 12" long, 3/8"
diameter,
looks pretty strong, looks real conductive.

Well done! I've been looking for graphite block electrodes on the right
side
of the pond without much (any) success, but I can get 13mm...1/2" gouging
electrodes at £35/100. I can live with that price for something that
works.

I'll be waiting for the test report.


Thanks for the idea.


Mark Rand
RTFM

I've used lead sheet - easy to cut and fold over tank edge, large area.

Jordan

George Willer wrote:
What am I missing here? I use FREE electrodes that will last nearly forever
unless the polarity gets accidentally reversed. I find them along the road
disguised as stainless wheel covers. The current one is from a Buick. I
like it better than the Cadillac one it replaces.

George Willer wrote:
What am I missing here? I use FREE electrodes that will last nearly forever
unless the polarity gets accidentally reversed. I find them along the road
disguised as stainless wheel covers. The current one is from a Buick. I
like it better than the Cadillac one it replaces.

Does your solution slowly turn yellow? That's hexavalent chromium, and it's
DEADLY POISON. That's why it's strongly suggested not to use stainless electrodes.

GWE

Jordan wrote:

I've used lead sheet - easy to cut and fold over tank edge, large area.

How does it work out long term?

GWE

Sorry, I need to make a correction.
It wasn't for derusting, rather for removing old chrome and nickel plating.
Maybe it could do for derusting too?
At college (hobby course in electoplating) we just used 50% solution of
some acid (HCl?) to remove rust - no electricity.

Jordan

Grant Erwin wrote:
Jordan wrote:

I've used lead sheet - easy to cut and fold over tank edge, large area.


How does it work out long term?

GWE

No, it doesn't turn yellow... should it? Just to be safe I'll refrain from
ingesting the glop from the tank. I have noticed the stainless gaining a
tinge from the paint color of the part being de-rusted. It wipes right off
so it may not be electrically deposited, but simple settling.

George Willer


"Grant Erwin" wrote in message
...
George Willer wrote:
What am I missing here? I use FREE electrodes that will last nearly
forever unless the polarity gets accidentally reversed. I find them
along the road disguised as stainless wheel covers. The current one is
from a Buick. I like it better than the Cadillac one it replaces.

Does your solution slowly turn yellow? That's hexavalent chromium, and
it's DEADLY POISON. That's why it's strongly suggested not to use
stainless electrodes.

GWE

"George Willer" wrote in message
...
No, it doesn't turn yellow... should it?

That would mean the electrode is reacting, I'm assuing it isn't supposed
to...

Just to be safe I'll refrain from ingesting the glop from the tank.

Cr6+ can be absorbed through the skin as well, so wear gloves around it.
(Cr3+ is almost as harmless as table salt, in contrast.)

Cr6+ is easily reduced, if you have some ferrous sulfate or sodium bisulfite
(or any sulf_ite_ for that matter, including SO2 gas) on hand, that'll
reduce it no problem.

I have noticed the stainless gaining a
tinge from the paint color of the part being de-rusted. It wipes right
off
so it may not be electrically deposited, but simple settling.

Paint is usually an insulator so that sounds about right.

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms