Hi all,

As a spinoff of my recent 'Drake drum skimming' trailer restoration
thread I'm currently (ouch) giving this 'electrolytic de-rusting' or
'cathodic cleaning' of the brake drums a go (thanks to Peter Parry for
the heads up).

http://www.remap-internet.org.uk/rem...tic+De-Rusting

This can be a 'before' shot of the frictionable surface.

http://dl.dropbox.com/u/5772409/Drum2.jpg

So, I've got one of those large grey tough-plastic workshop storage
tray / bins filled with ~7 gallons of warm water with a mug of washing
soda thrown in (should work out to about 1 teaspoonful / pint).

I wired a bit of coat hanger under one of the wheel studs, held in
place by a wheel nut put on backwards. The two drums sat in the
solution ok with the coat hanger connectors sticking out and touching.

For the anode I initially used a 1m length of 1/2" diameter metal bar
I had kicking around laid in the box.

I hooked it up to my 12V / 4A bench PSU and instantly noticed a cloud
of bubbles from the outside of the drums nearest the anode. It was
drawing about 3A.

I then added another anode into the opposite side and joined the two
with a short jump lead and whilst I saw bubble off the drums on that
side it was reduced because the PSU was current limiting and the
voltage had dropped to about 10V.

I then dug out a spare PC PSU (as per the suggestion in the link), cut
all the 12V (Yellow) and similar number of earths (black) and the On
wire (green) and earth and stripped and twisted them up in the right
groups. Joined the Yellow to my anodes and the black to my drums and
shorted the green to the black and away it went (11.8V on my DMMM).

However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

Am I on the right track or will it do all over in time in any case?

Cheers, T i m

p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

In message , T i m
writes



p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

If it might erode the bearing surfaces, could this be minimised by
greasing them surfaces well? Or would the alkaline solution tend to
remove the grease?
--
Ian

On Wed, 13 Jul 2011 12:14:36 +0100, T i m wrote:

However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes

Yup, "nearest the anodes" does that, as the current takes the paths of least (or
at least lesser) resistance.

and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

I have used aluminum foil to shape and electrode. This will dissolve eventually,
leaving a black mess, though, but it's convenient.

Am I on the right track or will it do all over in time in any case?

Wait and see.

p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

Nope, not unless you have misconnected the wires. It reacts away the rust,
turning it back to iron. Flaky rust bits turn back to smaller flaky iron bits,
not the original surface, though. The iron surface will be microscopically rough
and will rust again very quickly, so give it a wipe with an oily rag once you've
washed the soda water off.

Thomas Prufer

On Wed, 13 Jul 2011 12:41:28 +0100, Ian Jackson
wrote:

In message , T i m
writes



p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

If it might erode the bearing surfaces, could this be minimised by
greasing them surfaces well? Or would the alkaline solution tend to
remove the grease?

Good thought and I think you might be right as when I just pulled one
of the drums out to check it's progress (it's doing well g) the
greasy surfaces seemed to still be greasy.

From what Thomas mentions later is that it should be ok unprotected
though (as long as you wire it up right). ;-)

Cheers, T i m

On 13/07/2011 13:17, T i m wrote:
On Wed, 13 Jul 2011 12:41:28 +0100, Ian Jackson
wrote:

In , T i m
writes



p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

If it might erode the bearing surfaces, could this be minimised by
greasing them surfaces well? Or would the alkaline solution tend to
remove the grease?

Good thought and I think you might be right as when I just pulled one
of the drums out to check it's progress (it's doing wellg) the
greasy surfaces seemed to still be greasy.

From what Thomas mentions later is that it should be ok unprotected
though (as long as you wire it up right). ;-)


The article implies that a thin layer of porous iron is built up. That
might not be strong enough to withstand roller bearings without
collapsing. I think I would stick with the grease!

On Wed, 13 Jul 2011 13:56:10 +0200, Thomas Prufer
wrote:

On Wed, 13 Jul 2011 12:14:36 +0100, T i m wrote:

However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes

Yup, "nearest the anodes" does that, as the current takes the paths of least (or
at least lesser) resistance.

Understood.

and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

I have used aluminum foil to shape and electrode. This will dissolve eventually,
leaving a black mess, though, but it's convenient.

OK, so it is a valid thought then.

Am I on the right track or will it do all over in time in any case?

Wait and see.

Oh Daaaad. ;-(

Being that it's not an acid concoction as such I've just had a quick
peek and it looks like it's already processed the rust all around the
outside of the drum across half the width. ;-)

p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

Nope, not unless you have misconnected the wires.

phew

It reacts away the rust,
turning it back to iron.

Isn't chemistry clever. It's a bit like a Thermos flask. They keep hot
things hot and cold things cold but how do they know what to do?
ducks

Flaky rust bits turn back to smaller flaky iron bits,
not the original surface, though.

When I just lifted it out I think it was also stripping the paint that
was still present on the face that touches the back of the wheel.

The iron surface will be microscopically rough
and will rust again very quickly, so give it a wipe with an oily rag once you've
washed the soda water off.

Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

I'm thinking a central heating header tank maybe? Waterbut drain near
a bottom corner and an upturned square bucket stuck on the end to hold
the PC PSU out of the elements? ;-)

Cheers, T i m

On 13/07/2011 13:40, T i m wrote:
On Wed, 13 Jul 2011 13:56:10 +0200, Thomas Prufer
wrote:

On Wed, 13 Jul 2011 12:14:36 +0100, T i wrote:

However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes

Yup, "nearest the anodes" does that, as the current takes the paths of least (or
at least lesser) resistance.

Understood.

and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

I have used aluminum foil to shape and electrode. This will dissolve eventually,
leaving a black mess, though, but it's convenient.

OK, so it is a valid thought then.

Am I on the right track or will it do all over in time in any case?

Wait and see.

Oh Daaaad. ;-(

Being that it's not an acid concoction as such I've just had a quick
peek and it looks like it's already processed the rust all around the
outside of the drum across half the width. ;-)

p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

Nope, not unless you have misconnected the wires.

phew

It reacts away the rust,
turning it back to iron.

Isn't chemistry clever. It's a bit like a Thermos flask. They keep hot
things hot and cold things cold but how do they know what to do?
ducks

Flaky rust bits turn back to smaller flaky iron bits,
not the original surface, though.

When I just lifted it out I think it was also stripping the paint that
was still present on the face that touches the back of the wheel.

The iron surface will be microscopically rough
and will rust again very quickly, so give it a wipe with an oily rag once you've
washed the soda water off.

Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

I'm thinking a central heating header tank maybe? Waterbut drain near
a bottom corner and an upturned square bucket stuck on the end to hold
the PC PSU out of the elements? ;-)


LOL - I think ventilation is rather important. The lid might become
detached rather violently!!

On Jul 13, 1:40*pm, T i m wrote:
On Wed, 13 Jul 2011 13:56:10 +0200, Thomas Prufer

wrote:
On Wed, 13 Jul 2011 12:14:36 +0100, T i m wrote:

However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes

Yup, "nearest the anodes" does that, as the current takes the paths of least (or
at least lesser) resistance.

Understood.



and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

I have used aluminum foil to shape and electrode. This will dissolve eventually,
leaving a black mess, though, but it's convenient.

OK, so it is a valid thought then.



Am I on the right track or will it do all over in time in any case?

Wait and see.

Oh Daaaad. ;-(

Being that it's not an acid concoction as such I've just had a quick
peek and it looks like it's already processed the rust all around the
outside of the drum across half the width. ;-)



p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?

Nope, not unless you have misconnected the wires.

phew

It reacts away the rust,
turning it back to iron.

Isn't chemistry clever. It's a bit like a Thermos flask. They keep hot
things hot and cold things cold but how do they know what to do?
ducks

Flaky rust bits turn back to smaller flaky iron bits,
not the original surface, though.

When I just lifted it out I think it was also stripping the paint that
was still present on the face that touches the back of the wheel.

The iron surface will be microscopically rough
and will rust again very quickly, so give it a wipe with an oily rag once you've
washed the soda water off.

Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

I'm thinking a central heating header tank maybe? Waterbut drain near
a bottom corner and an upturned square bucket stuck on the end to hold
the PC PSU out of the elements? ;-)

Cheers, T i m

Do NOT apply any oil to the inside surface, or your brake shoes will
be ruined, and your travel more dangerous. I doubt there's any point
applying anything where the brake shoes meet, as all films will be
promptly stripped off, or in the case of oil or grease make the brakes
fail. If there's spongy iron on there, the first drive should strip it
off.

An electrode above or inside would prioritise interior cleaning.


NT

On Jul 13, 1:40*pm, T i m wrote:

Isn't chemistry clever. It's a bit like a Thermos flask. They keep hot
things hot and cold things cold but how do they know what to do?
ducks

"What have you got in it?"

"Two cups of coffee and a Choc ice"

NT wrote:
On Jul 13, 1:40 pm, T i m wrote:
On Wed, 13 Jul 2011 13:56:10 +0200, Thomas Prufer

wrote:
On Wed, 13 Jul 2011 12:14:36 +0100, T i m wrote:
However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes
Yup, "nearest the anodes" does that, as the current takes the paths of least (or
at least lesser) resistance.
Understood.



and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?
I have used aluminum foil to shape and electrode. This will dissolve eventually,
leaving a black mess, though, but it's convenient.
OK, so it is a valid thought then.



Am I on the right track or will it do all over in time in any case?
Wait and see.
Oh Daaaad. ;-(

Being that it's not an acid concoction as such I've just had a quick
peek and it looks like it's already processed the rust all around the
outside of the drum across half the width. ;-)



p.s. And this isn't going to affect the non rusty metal is it? ie, I'm
not going to erode anything off my bearing mount surfaces?
Nope, not unless you have misconnected the wires.
phew

It reacts away the rust,
turning it back to iron.
Isn't chemistry clever. It's a bit like a Thermos flask. They keep hot
things hot and cold things cold but how do they know what to do?
ducks

Flaky rust bits turn back to smaller flaky iron bits,
not the original surface, though.
When I just lifted it out I think it was also stripping the paint that
was still present on the face that touches the back of the wheel.

The iron surface will be microscopically rough
and will rust again very quickly, so give it a wipe with an oily rag once you've
washed the soda water off.
Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

I'm thinking a central heating header tank maybe? Waterbut drain near
a bottom corner and an upturned square bucket stuck on the end to hold
the PC PSU out of the elements? ;-)

Cheers, T i m

Do NOT apply any oil to the inside surface, or your brake shoes will
be ruined, and your travel more dangerous. I doubt there's any point
applying anything where the brake shoes meet, as all films will be
promptly stripped off, or in the case of oil or grease make the brakes
fail. If there's spongy iron on there, the first drive should strip it
off.

+1

An electrode above or inside would prioritise interior cleaning.

+1

NT

On Wed, 13 Jul 2011 13:44:29 +0100, Fredxx wrote:


Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

I'm thinking a central heating header tank maybe? Waterbut drain near
a bottom corner and an upturned square bucket stuck on the end to hold
the PC PSU out of the elements? ;-)


LOL - I think ventilation is rather important. The lid might become
detached rather violently!!

Quite and hence why I was continuing the 'this needs to stay outside'
theme. ;-)


As I have quite a few PC PSU's kicking about and soda being cheap I'm
thinking I can easily have a couple of these things on the go at once
if I have a particular project in hand.

I was even thinking of having a 'bus bar' along the top of my tank
where I could make up some coat hanger hangers to support the smaller
bits whilst giving them an electric connection?

Even the 'kids' (21/20) are fascinated watching it all bubbling away.
;-)

Cheers, T i m

On 13/07/2011 12:14, T i m wrote:
....
However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes

That is the shadow effect. Any bits in an electrical shadow, as seen
from the electrodes, will be done slowly, if at all.

and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

Am I on the right track or will it do all over in time in any case?...

It is the way I would go about it.

Colin Bignell

On Wed, 13 Jul 2011 13:40:11 +0100, T i m wrote:

When I just lifted it out I think it was also stripping the paint that
was still present on the face that touches the back of the wheel.

The hydrogen bubbles it off, as it were.

Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Yup. I wouldn't worry about ruining brake shoes -- I said wipe it with oily rag,
not "oil" it or "apply coat of grease".


Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

Naah. The solution turns pretty foul quickly, and it's not as if there's any
money tied up in it. I wouldn't drain it into the grouang, as it'll be a
witches' brew of oil, paint, rust, dissolved aluminum, and dirt. And venting
the hydrogen is a good idea, too.

Thomas Prufer

On Wed, 13 Jul 2011 06:23:03 -0700 (PDT), NT
wrote:


Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.


Do NOT apply any oil to the inside surface, or your brake shoes will
be ruined, and your travel more dangerous.

Even if wiped off beforehand with panel wipe, brake cleaner or acetone
(they are my usual solvents for such tasks).

I doubt there's any point
applying anything where the brake shoes meet, as all films will be
promptly stripped off, or in the case of oil or grease make the brakes
fail.

I think we were talking about more when the drum was in store / off
the actual trailer as such but your points are welcomed and noted.

If there's spongy iron on there, the first drive should strip it
off.

Ok.

An electrode above or inside would prioritise interior cleaning.

I've, just made up one from a opened out coat hanger and spaced off
the drum with 4 rings of 15mm foam pipe insulation plus cable ties and
held submerged with some strips of wood. It does seem to be more
chemically active in the drum with the added ring. ;-)

I'm guessing all these extra electrodes all add to the general current
load?

Cheers, T i m

p.s. I just spoke to our local Jewsons and a 6m length of 12mm Rebar
is about 12 quid. You could make quite a few anodes with that. ;-)

On Wed, 13 Jul 2011 06:30:17 -0700 (PDT), Mark Bluemel
wrote:

On Jul 13, 1:40*pm, T i m wrote:

Isn't chemistry clever. It's a bit like a Thermos flask. They keep hot
things hot and cold things cold but how do they know what to do?
ducks

"What have you got in it?"

"Two cups of coffee and a Choc ice"

big grin

Cheers, T i m

On Wed, 13 Jul 2011 16:27:51 +0200, Thomas Prufer
wrote:

On Wed, 13 Jul 2011 13:40:11 +0100, T i m wrote:

When I just lifted it out I think it was also stripping the paint that
was still present on the face that touches the back of the wheel.

The hydrogen bubbles it off, as it were.

Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Yup. I wouldn't worry about ruining brake shoes -- I said wipe it with oily rag,
not "oil" it or "apply coat of grease".

g I know. Did you know many new iron brake discs come covered in a
layer or oil / grease?

Ok, what I was thinking is that once this electro cleaning is finished
is washing the stuff off with plenty of water, seeing if the wire
brush / electric drill would improve it further and see if I can at
least get down to some consistency on the frictional part (possibly
some coarse wet n dry etc). Once done the best I can I would wipe it
all over with some panel wipe and once warmed in the sun, give it all
a blow over with some primer to stop it rusting again. I would try to
avoid the frictional area but wouldn't be too bothered if any paint
went on there. I would then refit it all to the suspension unit /if/ I
had all the other stuff ready. If I didn't then I might be inclined to
wipe the inside of the drum over with a bit of oil or WD40 knowing I
would ensure it was all washed off before refitting it.


Thinking ahead now I'm considering making a better tank (with a lid /
vent holes) so nothing gets in there if it's left outside and keeps
the rain out etc. Then I can similarly process the bigger bits like
the suspension arms (keeping the actual rubber parts out of it) and
brake back plates etc.

Naah. The solution turns pretty foul quickly, and it's not as if there's any
money tied up in it.

True.

I wouldn't drain it into the grouang, as it'll be a
witches' brew of oil, paint, rust, dissolved aluminum, and dirt.

So how should I dispose of it out of interest?

And venting
the hydrogen is a good idea, too.

I know. ;-)

Cheers, T i m

On Wed, 13 Jul 2011 15:23:46 +0100, "Nightjar \"cpb\"@"
"insertmysurnamehere wrote:

On 13/07/2011 12:14, T i m wrote:
...
However it seems that (for now anyway) it's mainly reacting with the
outside of the drums nearest the anodes

That is the shadow effect.

Ok (logical name for it).

Any bits in an electrical shadow, as seen
from the electrodes, will be done slowly, if at all.

Is the 'fizzing' an indication of the process in action so if it stops
it's either complete or the solution is exhausted?

and I'm now thinking of
creating two rings of iron, sat inside the actual drum and isolated
from it with some suitable spacers (some garden hose segments or
similar) to try to focus the reaction more on the actual area in
question?

Am I on the right track or will it do all over in time in any case?...

It is the way I would go about it.

Ok and again makes sense if you consider how it works etc. I've got a
couple of turns of wire coat hanger in one drum as well now but as it
doesn't really matter about the outside of the drums (other than for
aesthetic reasons) I think I'll look to put something 'chunkier' in
there (larger surface area = greater effect?)

Cheers, T i m

On 13/07/2011 15:35, T i m wrote:
On Wed, 13 Jul 2011 06:23:03 -0700 (PDT),
wrote:


Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.


Do NOT apply any oil to the inside surface, or your brake shoes will
be ruined, and your travel more dangerous.

Even if wiped off beforehand with panel wipe, brake cleaner or acetone
(they are my usual solvents for such tasks).

I doubt there's any point
applying anything where the brake shoes meet, as all films will be
promptly stripped off, or in the case of oil or grease make the brakes
fail.

I think we were talking about more when the drum was in store / off
the actual trailer as such but your points are welcomed and noted.

If there's spongy iron on there, the first drive should strip it
off.

Ok.

An electrode above or inside would prioritise interior cleaning.

I've, just made up one from a opened out coat hanger and spaced off
the drum with 4 rings of 15mm foam pipe insulation plus cable ties and
held submerged with some strips of wood. It does seem to be more
chemically active in the drum with the added ring. ;-)


Don't forget any insulator will effectively cast a shadow on the drum.

On Jul 13, 12:14*pm, T i m wrote:
Hi all,

As a spinoff of my recent 'Drake drum skimming' trailer restoration
thread I'm currently (ouch) giving this 'electrolytic de-rusting' or
'cathodic cleaning' of the brake drums a go

I've never heard of "cathodic cleaning". There are two processes used
he one is a cathodic workpiece and used for de-rusting, not
cleaning. The other is an anode workpiece and is used for electro-
polishing and anodic cleaning.

The big difference is that a cathode workpiece is self-limiting and
can be left unwatched. OTOH, an anodic brightening (a fine process)
needs very careful control and continuous monitoring, otherwise it
will not only damage the surface, it will eat great big holes through.

So when making your cathodic de-rusting rig, make sure the croc clips
are obvious. My rig uses pluggable cables to a front panel (cables
have a short service life), but the panel is clearly labelled and the
plugs & sockets are two different types to avoid mis-pluggings.

In article , T i m
writes
Once done the best I can I would wipe it
all over with some panel wipe and once warmed in the sun, give it all
a blow over with some primer to stop it rusting again. I would try to
avoid the frictional area but wouldn't be too bothered if any paint
went on there.

Primer is porous so this might do better in the long term (heat
resistant spray paint, no primer reqd):

http://www.toolstation.com/shop/p64927

or http://www.screwfix.com/p/arse/82049

--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

On Wed, 13 Jul 2011 17:04:42 +0100, Fredxx wrote:


I've, just made up one from a opened out coat hanger and spaced off
the drum with 4 rings of 15mm foam pipe insulation plus cable ties and
held submerged with some strips of wood. It does seem to be more
chemically active in the drum with the added ring. ;-)


Don't forget any insulator will effectively cast a shadow on the drum.

True, however I intended moving it about a bit. ;-)

There is something weird though and it may have been down to the fact
that coat hangers are plated or something? The one I made into a loop
and placed within the drum (on spacers) seems to have built up a whole
load of 'stuff' (much more than the main anodes) but even when used on
it's own doesn't seem to provoke the same sort of activity as the main
anodes did?


http://dl.dropbox.com/u/5772409/strange.jpg
http://dl.dropbox.com/u/5772409/strange%20close.jpg

I wish I'd done chemistry at school now. ;-(

Cheers, T i m

On Wed, 13 Jul 2011 18:00:26 +0100, fred wrote:

In article , T i m
writes
Once done the best I can I would wipe it
all over with some panel wipe and once warmed in the sun, give it all
a blow over with some primer to stop it rusting again. I would try to
avoid the frictional area but wouldn't be too bothered if any paint
went on there.

Primer is porous so this might do better in the long term (heat
resistant spray paint, no primer reqd):

http://www.toolstation.com/shop/p64927

or http://www.screwfix.com/p/arse/82049


Good idea, thanks. ;-)

T i m

On Wed, 13 Jul 2011 09:33:11 -0700 (PDT), Andy Dingley
wrote:

On Jul 13, 12:14*pm, T i m wrote:
Hi all,

As a spinoff of my recent 'Drake drum skimming' trailer restoration
thread I'm currently (ouch) giving this 'electrolytic de-rusting' or
'cathodic cleaning' of the brake drums a go

I've never heard of "cathodic cleaning".

Ah. I was just going by what it said he

http://www.remap-internet.org.uk/rem...tic+De-Rusting

" At the cathode (the object being de-rusted) the negative wire
supplies electrons. Therefore, something must gain electrons at the
cathode (reduction). Two things are reduced at the cathode, water and
the rusty iron. The evolution of hydrogen from the water plays a
beneficial role in the cleaning process. The tiny bubbles forming at
the surface blast things off the surface that aren't stuck tightly.
Loose rust, grease and even paint are removed by the action of the
hydrogen bubbles. This process is sometimes called cathodic cleaning."


There are two processes used
he one is a cathodic workpiece and used for de-rusting, not
cleaning.

Ok.

The other is an anode workpiece and is used for electro-
polishing and anodic cleaning.

Right.

The big difference is that a cathode workpiece is self-limiting and
can be left unwatched.

As it mentions in the text (and I liked the sound of. Nothing like
being half way to somewhere then remembering .... ).

OTOH, an anodic brightening (a fine process)
needs very careful control and continuous monitoring, otherwise it
will not only damage the surface, it will eat great big holes through.

And that's not good.

So when making your cathodic de-rusting rig, make sure the croc clips
are obvious. My rig uses pluggable cables to a front panel (cables
have a short service life),

(I think I may have got round this by using a bit of coat hanger to
bring the connection out of the solution).

but the panel is clearly labelled and the
plugs & sockets are two different types to avoid mis-pluggings.

Sounds like a good tip. I must admit to double checking I'd got them
round the right way and sorta remembered it as (sort of unusually
unless you are used to working on old cars g) the 'object' is -Ve.

Cheers and thanks for the warning. ;-)

Cheers, T i m

On 7/14/2011 2:20 AM, T i m wrote:

As I have quite a few PC PSU's kicking about and soda being cheap I'm
thinking I can easily have a couple of these things on the go at once
if I have a particular project in hand.

I was even thinking of having a 'bus bar' along the top of my tank
where I could make up some coat hanger hangers to support the smaller
bits whilst giving them an electric connection?

Even the 'kids' (21/20) are fascinated watching it all bubbling away.
;-)

Cheers, T i m


It looks as if you may have found your true vocation. ;-)

On Jul 13, 3:35*pm, T i m wrote:
On Wed, 13 Jul 2011 06:23:03 -0700 (PDT), NT
wrote:

Understood. I'll probably give the outsides a blow over with some red
oxide primer and the inside a wipe with an oily rag.

Do NOT apply any oil to the inside surface, or your brake shoes will
be ruined, and your travel more dangerous.

Even if wiped off beforehand with panel wipe, brake cleaner or acetone
(they are my usual solvents for such tasks).

Well... you takes your chances if you want. Oil on brake shoes soaks
in and comes out very very slowly, effectively ruining them. I cant
see a light rust film being a problem.


I doubt there's any point
applying anything where the brake shoes meet, as all films will be
promptly stripped off, or in the case of oil or grease make the brakes
fail.

I think we were talking about more when the drum was in store / off
the actual trailer as such but your points are welcomed and noted.

If there's spongy iron on there, the first drive should strip it
off.

Ok.



An electrode above or inside would prioritise interior cleaning.

I've, just made up one from a opened out coat hanger and spaced off
the drum with 4 rings of 15mm foam pipe insulation plus cable ties and
held submerged with some strips of wood. It does seem to be more
chemically active in the drum with the added ring. ;-)

I dont see any need for fancy shapes, just a bit of metal poked in the
water is fine.


I'm guessing all these extra electrodes all add to the general current
load?

Yes, I assumed you'd remove the outside electrodes, since there's no
reason to strip the rust & paint on the outside.


Cheers, T i m

p.s. I just spoke to our local Jewsons and a 6m length of 12mm Rebar
is about 12 quid. You could make quite a few anodes with that. ;-)

Scrap food cans are surely cheaper, and dont need cutting.


NT

On 13/07/2011 18:42, T i m wrote:
On Wed, 13 Jul 2011 17:04:42 +0100, wrote:


I've, just made up one from a opened out coat hanger and spaced off
the drum with 4 rings of 15mm foam pipe insulation plus cable ties and
held submerged with some strips of wood. It does seem to be more
chemically active in the drum with the added ring. ;-)


Don't forget any insulator will effectively cast a shadow on the drum.

True, however I intended moving it about a bit. ;-)

There is something weird though and it may have been down to the fact
that coat hangers are plated or something? The one I made into a loop
and placed within the drum (on spacers) seems to have built up a whole
load of 'stuff' (much more than the main anodes) but even when used on
it's own doesn't seem to provoke the same sort of activity as the main
anodes did?


I would imagine that coat hangers are plated, though whether it's zinc
I'm not sure. I thought zinc oxide was white though with iron oxide
contaminants who knows.

Any current that flows ought to be a function of anode surface area and
distance. A wire doesn't have a lot of area, how would this compare
with your main anodes? Zinc oxide is a pretty good insulator as well.

On Wed, 13 Jul 2011 16:19:41 +0100, T i m wrote:

Is the 'fizzing' an indication of the process in action so if it stops
it's either complete or the solution is exhausted?

No, the fizzing will continue even if all the rust is gone. The solution won't
exhaust, the soda is just there to let the water conduct better and doesn't get
used up.

Ok and again makes sense if you consider how it works etc. I've got a
couple of turns of wire coat hanger in one drum as well now but as it
doesn't really matter about the outside of the drums (other than for
aesthetic reasons) I think I'll look to put something 'chunkier' in
there (larger surface area = greater effect?)

The larger the surface, the less resistance, the more current for a given
voltage. S'why I like the ally foil...

The electrodes get eaten by the oxygen produced, so don't spend money on them.
I'd pour the solution down the drain -- no worse than oven cleaner on an
aluminum pan or sheet can be.

Beware that you've got a hydrogen-oxygen mix in the perfect ratio to go bang,
and bits of metal connected to a power source that will spark, even underwater.
And your power supplies might not take kindly to a short-circuit. You *will*
short circuit the drums and electrodes, eventually. Might want to stick in some
sort of fuse, even if it's just an inch or three of single copper strand in a
choc block.


Thomas Prufer

On 14 Jul 2011 09:20:20 GMT, Huge wrote:

IRTA "Catholic Cleaning".

Baptism, innit?

Thomas Prufer

On Wed, 13 Jul 2011 15:23:55 -0700 (PDT), NT
wrote:


Even if wiped off beforehand with panel wipe, brake cleaner or acetone
(they are my usual solvents for such tasks).

Well... you takes your chances if you want.

Seems to have worked before?

Oil on brake shoes soaks
in and comes out very very slowly, effectively ruining them.

Well the worst case was I had a an old moped that soaked it's brake
shoes in oil (engine in the rear wheel and a seal went). I boiled them
in detergent and they worked fine thereafter. However, I wouldn't
contaminate them on purpose and am careful to not do so when
reassembling any brakes etc.

I cant
see a light rust film being a problem.

Agreed, but you know when you think these things are going to only be
a couple of weeks then take 6 months ...


I've, just made up one from a opened out coat hanger and spaced off
the drum with 4 rings of 15mm foam pipe insulation plus cable ties and
held submerged with some strips of wood. It does seem to be more
chemically active in the drum with the added ring. ;-)

I dont see any need for fancy shapes, just a bit of metal poked in the
water is fine.

If you saw it in action it would suggest different. The 'reaction' is
much more visible nearer the electrodes are to each other.


I'm guessing all these extra electrodes all add to the general current
load?

Yes, I assumed you'd remove the outside electrodes, since there's no
reason to strip the rust & paint on the outside.

I hadn't initially as I didn't /mind/ if it also stripped the rust off
the studs and the other areas. I started it all running again first
thing this morning and I'm going to take one out and give it a rinse
and clean and see just how complete the processes has been. If it
still needs more on the inside of the drum I might restart with some
fresh solution and 'internal' electrodes only.

p.s. I just spoke to our local Jewsons and a 6m length of 12mm Rebar
is about 12 quid. You could make quite a few anodes with that. ;-)

Scrap food cans are surely cheaper, and dont need cutting.

Ah, good thought, if I can find something of a large enough diameter
that we need to use up out of the cupboard. ;-)

Cheers, T i m

On Thu, 14 Jul 2011 11:13:43 +0200, Thomas Prufer
wrote:

On Wed, 13 Jul 2011 16:19:41 +0100, T i m wrote:

Is the 'fizzing' an indication of the process in action so if it stops
it's either complete or the solution is exhausted?

No, the fizzing will continue even if all the rust is gone.

Ok.

The solution won't
exhaust, the soda is just there to let the water conduct better and doesn't get
used up.

Understood, thanks.

Ok and again makes sense if you consider how it works etc. I've got a
couple of turns of wire coat hanger in one drum as well now but as it
doesn't really matter about the outside of the drums (other than for
aesthetic reasons) I think I'll look to put something 'chunkier' in
there (larger surface area = greater effect?)

The larger the surface, the less resistance, the more current for a given
voltage. S'why I like the ally foil...

Hmm, and easier to form into a ring .. ;-)

The electrodes get eaten by the oxygen produced, so don't spend money on them.

I was thinking a 12mm diameter length of Rebar could probably be used
for a fair time though?

I'd pour the solution down the drain -- no worse than oven cleaner on an
aluminum pan or sheet can be.

I was thinking that. This morning (left overnight) the material has
settled out and left the 'water' pretty clear. I could remove the hubs
then let it all settle again and just put the sludgy bit in some
newspaper and in the bin?

Beware that you've got a hydrogen-oxygen mix in the perfect ratio to go bang,
and bits of metal connected to a power source that will spark, even underwater.

Ok.

And your power supplies might not take kindly to a short-circuit.

True.

You *will*
short circuit the drums and electrodes, eventually.

;-)

Might want to stick in some
sort of fuse, even if it's just an inch or three of single copper strand in a
choc block.

Good idea. At the moment it's all pretty 'Heath Robinson' with wires
twisted together etc (not really 'me' but it worked so ..).

Thanks very much for all your help and advice so far.

Cheers, T i m

On Thu, 14 Jul 2011 12:22:07 +0100, T i m wrote:

I was thinking a 12mm diameter length of Rebar could probably be used
for a fair time though?

Yes, but you don't need thickness as much as area. Less shadowing and less
resistance, so sheet metal would be better. Some sites recommend using
stainless, as some types don't get attacked as much by the oxygen. So see if you
can find something stainless free, like a washing machine drum, or an old sink.

I was thinking that. This morning (left overnight) the material has
settled out and left the 'water' pretty clear. I could remove the hubs
then let it all settle again and just put the sludgy bit in some
newspaper and in the bin?

Sounds good.

Thomas Prufer

On Thu, 14 Jul 2011 17:11:08 +0200, Thomas Prufer
wrote:

On Thu, 14 Jul 2011 12:22:07 +0100, T i m wrote:

I was thinking a 12mm diameter length of Rebar could probably be used
for a fair time though?

Yes, but you don't need thickness as much as area. Less shadowing and less
resistance, so sheet metal would be better.

Gotcha.

Some sites recommend using
stainless, as some types don't get attacked as much by the oxygen. So see if you
can find something stainless free, like a washing machine drum, or an old sink.

Hmmm ... ;-)

I was thinking that. This morning (left overnight) the material has
settled out and left the 'water' pretty clear. I could remove the hubs
then let it all settle again and just put the sludgy bit in some
newspaper and in the bin?

Sounds good.

Cool.

I've just taken one drum out again and it is looking very good. I gave
it a quick wipe round with a Brillo pad and it does seem to be back to
the base metal, even on the frictionable part (so much so you can now
feel a slight wear ridge on the inside) . ;-)

I did feel a couple of 'bit's' but still but nothing that wouldn't
come off with a quick scrape.

Right, now to find something to that will take the rusty end of the
suspension units. ;-)

Cheers, T i m

Thomas Prufer wrote:
On 14 Jul 2011 09:20:20 GMT, Huge wrote:

IRTA "Catholic Cleaning".

Baptism, innit?


Born-again brake drums?

Thomas Prufer

I keep reading this thread as "Catholic cleaning".

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article , T i m
writes

I've just taken one drum out again and it is looking very good. I gave
it a quick wipe round with a Brillo pad and it does seem to be back to
the base metal, even on the frictionable part (so much so you can now
feel a slight wear ridge on the inside) . ;-)

I did feel a couple of 'bit's' but still but nothing that wouldn't
come off with a quick scrape.

Right, now to find something to that will take the rusty end of the
suspension units. ;-)

More pics when ready please, I'm enjoying this one :-).
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

On Thu, 14 Jul 2011 23:08:30 +0100, fred wrote:

In article , T i m
writes

I've just taken one drum out again and it is looking very good. I gave
it a quick wipe round with a Brillo pad and it does seem to be back to
the base metal, even on the frictionable part (so much so you can now
feel a slight wear ridge on the inside) . ;-)

I did feel a couple of 'bit's' but still but nothing that wouldn't
come off with a quick scrape.

Right, now to find something to that will take the rusty end of the
suspension units. ;-)

More pics when ready please, I'm enjoying this one :-).


Right, before and afters of the drum but the inside has only had the
anodes on the outside (so most of the inside would have been in
'shadow' as such).

http://dl.dropbox.com/u/5772409/Drum1.jpg
http://dl.dropbox.com/u/5772409/Drum1a.jpg

http://dl.dropbox.com/u/5772409/Drum2.jpg
http://dl.dropbox.com/u/5772409/Drum2a.jpg

We did give the drums a good wash down and the insides a quick wipe
over with a Brillo pad but I think you can see a marked improvement.

Towards the end, rather than having the drums insides facing upwards
side-by-side in a flattish box with the anodes running down both the
long sides (at an angle as they were longer than the box) we stood the
drums on edge at either end with the insides facing the middle and the
anodes also in the middle but only half the hub submerged. You could
see the bit that had been submerged further de-rusted after only half
an hour or so.

Yesterday I found another otherwise good PC PSU that had a burnt main
connector [1] so I opened the case and trimmed all but the 12V and
equivalent number of grounds and the start and earth wires back to the
board. Then I stripped the ends, twisted them together (in groups g)
and soldered a couple of meters of heavy duty (17A) red / black flex
to that (and suitably heatshrinked). As this PSU has a mains on/off
switch I'm probably also going to join the start / earth pair together
inside as well so it becomes a straight 12V PSU. I'm also going to fit
car blade type inline fuse holders as per Thomas's suggestion.

This means I can run two systems independently (as there are a fair
few bits I need de-rusting). ;-)

Cheers, T i m


[1] This project has been a good reminder re why I rarely throw
anything away g. Even when faulty as for it's primary purpose it may
well have a perfectly good secondary one without smelting it down and
re-forming it into something else. ;-)

In article , T i m
writes
On Thu, 14 Jul 2011 23:08:30 +0100, fred wrote:

More pics when ready please, I'm enjoying this one :-).

Right, before and afters of the drum but the inside has only had the
anodes on the outside (so most of the inside would have been in
'shadow' as such).

http://dl.dropbox.com/u/5772409/Drum1.jpg
http://dl.dropbox.com/u/5772409/Drum1a.jpg

http://dl.dropbox.com/u/5772409/Drum2.jpg
http://dl.dropbox.com/u/5772409/Drum2a.jpg

We did give the drums a good wash down and the insides a quick wipe
over with a Brillo pad but I think you can see a marked improvement.

Excellent result, the close-up pics show how much it has been improved.

For me it is the potential of cleaning the more intricate parts that
would be of benefit, if I had looked inside the hub you showed in
previous pics I probably would have scrapped the lot on the spot.

more good stuff snipped
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

On Fri, 15 Jul 2011 09:56:36 +0100, fred wrote:


Excellent result, the close-up pics show how much it has been improved.

We (even the Mrs) are all finding it quite fascinating. How you can
put something in what is basically water and pull it out a while later
looking a lot lot better and with no noise, real effort, chemicals (in
the nasty acid sense), much cost or risk so we are still waiting for
the gotcha. That and the soda concentration doesn't dilute or deplete
with use apparently etc etc ... ? ;-)


For me it is the potential of cleaning the more intricate parts that
would be of benefit,

Same here, or more difficult to access (inside stuff) than intricate
as such.

if I had looked inside the hub you showed in
previous pics I probably would have scrapped the lot on the spot.

;-)

I guess it's something I've just done since I can remember.

My first cycle was found in a ditch all overgrown and recovered,
handed in to the police station, collected 6 weeks later and
'restored'. I think used it for school and a couple of cycling trips.
;-)


I've picked up mopeds in wheelbarrows, brought half motorbikes home,
half on their own wheels and the other half on my (home made)
go/box-cart and bought cheap / been given many a motor vehicle in a
sorry state and brought them back to life.

The most visually effective was an old but low mileage MZ ETZ 251
Saxon Tour that got caught up in a Bike Shop fire and I was given once
it had been written off under their insurance.

http://dl.dropbox.com/u/5772409/mz1.jpg

http://dl.dropbox.com/u/5772409/mz2.jpg

http://dl.dropbox.com/u/5772409/mz3.jpg

http://dl.dropbox.com/u/5772409/mz4.jpg

http://dl.dropbox.com/u/5772409/mz5.jpg

Cost about 200 quid in second hand parts and I ran it for about 6
months till a mate needed a bike and I needed some cash. The last pic
shows it after a couple of weeks and awaiting the new seat cover.

40k+ miles later he offered it to my daughter on the grounds that if
she could start and ride it it was hers for nowt.

She even prefers it's new colour scheme. ;-)

http://dl.dropbox.com/u/5772409/mz6.jpg

She took the screen off though because (apparently) they are for
sissy's (he says looking at the very large screen and fairing on his
old BMW boxer). Doh! ;-)

Cheers, T i m

p.s. When I was IT training in the city a fellow instructor was from
South Africa (although he was born and lived in Scotland for many
years) leaving his family over there whilst trying to set up a new
home for them all over here. He was going though a bit of a bad patch
and through conversation it turned out he had been a biker years
before so I asked him if he would like to join us for a long weekend
motorcycle camping. I put him on the MZ insurance, dug out some spare
bike kit, tent and sleeping bag and after some initial checks to make
sure he still had the knack we set off!

It was really nice to see him forget all about his 'problems' for a
few days and he even found the MZ to be a fun little ride. His
backside wasn't up to 200 mile days on the MZ saddle though.
(Apparently his night vision was about as good as the MZ headlight so
after dusk he would just follow the lights on the trailer behind my
bike. ;-) )

On Thu, 14 Jul 2011 17:11:08 +0200, Thomas Prufer
wrote:

On Thu, 14 Jul 2011 12:22:07 +0100, T i m wrote:

I was thinking a 12mm diameter length of Rebar could probably be used
for a fair time though?

Yes, but you don't need thickness as much as area. Less shadowing and less
resistance, so sheet metal would be better. Some sites recommend using
stainless, as some types don't get attacked as much by the oxygen. So see if you
can find something stainless free, like a washing machine drum, or an old sink.

I may have an old stainless sink on it's way (if his Mrs hasn't
already thrown it out). I also know someone who works in a shop
fitters on stainless units who may be able to save me some offcut /
strips etc.

Another question though if I may (along those lines).

To give the drums another shot but with the focus on the insides I
bought a low dustbin sized tub and found a (zinc?) plated / plastic
coated (one side) side panel (Dexion shelving) in the workshop that
was thin enough to sorta hand roll to sit on-edge inside the bottom /
sides of said tub like a lining (zinc face inwards). I put the drums
back to back in the middle on edge and drums facing outwards and then
some plastic sink grid things either side to stop them rolling about
but allow the process freely though them. Fresh batch of solution
and the properly wired / fused second PSU and it's really going (the
20A blade type fuse holder was getting noticeably warm)!

Now, initially I didn't see any of the typical brown-sludge 'build up'
on the inside of the sheet but when I clipped a couple of bits of
chrome .. old PC case steel to the sheet they seemed to gunge up
pretty quickly?

The question, does it 'matter' what the surface finish is of the
anodes for this process or is it sufficient that they are just
'conductors' please?

Cheers, T i m

p.s. I did try a small strip of ally foil that I rolled over a few
times and curved round the inside of one tub but it started to break
down and float about in the soup. ;-(

On Jul 17, 11:31*am, T i m wrote:

Fresh batch of solution
and the properly wired / fused second PSU and it's really going (the
20A blade type fuse holder was getting noticeably warm)!

I wouldn't run at more than 2A / sq ft. of surface. You can cause
corrosion faster than you're de-rusting if you start getting
electrolysis and too much obvious heating or bubbling.


It is useful to make up shaped anodes to fit inside some shapes. I
mostly use old microwave or washing machine scrap, tinsnipped up and
bent to shape - sometimes held or connected with stainless self
tappers (don't use or trust aluminium pop rivets!). A supply of coarse
plastic mesh (old laundry basket) can be handy too as an armature for
shaping or hanging stuff from, or as spacers to stop accidental
contacts.

Be aware of the waste issues (Erin Brockovich) if you use stainless
anodes. Certainly take your anodes out of the tank when the power is
off.