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Author: Subject: More on PbO2 electrodes
dann2
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[*] posted on 2-2-2007 at 15:18


Quote:
Originally posted by FrankRizzo
Quote:
Originally posted by dann2
I have put some more articles in the further reading section.
Someone here was looking for some of them, I cannot find the original post/name, appologies.

They are JES August 1961, July 1957 and March 1958.

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...


That was I looking for those articles. Thanks for posting them up on your page for everyone to access. Someone in the references thread (Solo, I believe) had access to them, and graciously uploaded them for me as well. Although the ideas in them are definitely aimed more toward industrial processes, they're nice reference material.




Hello,

It's a pleasure!!!!!

Would the (good) Solo, or indeed yourself have access to

JAE (or is it JES?) Perparation and Behaviours of Magnetite Anodes.
Vol. 8 No. 4 July 1978.

Would like to read it and cannot get my hands on it.

I have some more articles relating to making Manganese Dioxide, Cobolt Oxide Anodes, for Chlorate/Perchlorate making. I will put them up on the site soon.
The Manganese Anodes seem easy to make from simple chemicals (I've said that before ) but will they be a long lasting reliable Anode?????????
Would be good to avoid those's Lead Compounds.


Dann2
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[*] posted on 3-2-2007 at 05:32


When oxidation of a lead rod by NaOh solution does not work, then what is about an oxidation with H2O2 or some other oxidators?

Elektrolytical oxidation of a Pb rod shouldn´t be so hard, isn´t it?
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[*] posted on 3-2-2007 at 09:51


Yep, Solo posted it over in the references section. I'll attach it here as well.



Quote:
Originally posted by dann2
Hello,

It's a pleasure!!!!!

Would the (good) Solo, or indeed yourself have access to

JAE (or is it JES?) Perparation and Behaviours of Magnetite Anodes.
Vol. 8 No. 4 July 1978.

Would like to read it and cannot get my hands on it.

I have some more articles relating to making Manganese Dioxide, Cobolt Oxide Anodes, for Chlorate/Perchlorate making. I will put them up on the site soon.
The Manganese Anodes seem easy to make from simple chemicals (I've said that before ) but will they be a long lasting reliable Anode?????????
Would be good to avoid those's Lead Compounds.


Dann2


Attachment: Magnetite Anodes.pdf (438kB)
This file has been downloaded 1340 times

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[*] posted on 3-2-2007 at 10:55


Dann, check your U2U messages for info on 3 missing files on your site...
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[*] posted on 8-2-2007 at 02:17


Hi,
I had those idea to produce a little bit simpler electrodes:
1)To take any metal ant plate electrochemically PbO2 on it. After that glue with any acid resistant glue a plastic
sheet on the PbO2 side of the "electrode" and then dissolve the metal.
2)Glue magnetite or graphite powder on plastic, electroplate PbO2. glue another plastic on the PbO2 side and
scrape off the plastic/graphite.

This method spares making PbO2( which for me is a pain in the ass).

Do you guys think it can work?
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dann2
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[*] posted on 8-2-2007 at 18:51


Quote:
Originally posted by hashashan
Hi,
I had those idea to produce a little bit simpler electrodes:
1)To take any metal ant plate electrochemically PbO2 on it. After that glue with any acid resistant glue a plastic
sheet on the PbO2 side of the "electrode" and then dissolve the metal.
2)Glue magnetite or graphite powder on plastic, electroplate PbO2. glue another plastic on the PbO2 side and
scrape off the plastic/graphite.


Hello,

I will give my 2 cents worth and go for the following answer:

No.! I don't think it would work. The Lead Dioxide will probably crack and it will not be a nice consistent sheet of material for you to stick to the plastic. It needs to be a consistant sheet or you will not be able to get a connection to it when it is to be used in the cell.
You are in fact trying to make a massive Lead Dioxide Anode and then glue a piece of plascti to it. Why bother with the plastic. I suppose it will give it strength but if the Lead Dioxide is going to crack it will crack anyways with or without the plastic.
Try getting Lead Dioxide to plate onto/into a piece of cloth or some other sort of material (Titanium sponge/fine mesh) or something of that nature. You will then have a reinforced 'massive' Anode.
I made one of theses once (using a piece of polyester cloth) and had initial success. The Anode dissolved away. It did not fail cathostrophically (suddenly). I think I did not build up thick enough of a layer of Lead Dioxide. I called it my Cloth Reinforced Lead Dioxide Anode (CRLDA) :-)
Velcro might be interesting. It's Lead Compounds all the way though, it would be good of you could avaid them.
I ran out of enthusiasm (or did I get poisoned!).

Dann2
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[*] posted on 9-2-2007 at 05:11


actually i didnt mean to create a massive lead dioxide anode. but rather another process to make plastic with PbO2 coated on them.. the reason is that its a pain in the ass to make PbO2 powder and rub it into a plastic. so i thought that if i could first create the coating and then attach the plastic to it so it will gain strength then it would be ok.
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[*] posted on 9-2-2007 at 08:16


If you have a problem finding PbO2, look no further than your nearest lead-acid battery recycling pile or near dumpsters. If you empty the electrolyte and hacksaw off the top of the battery (a PITA), you'll gain access to the cells inside. The cells are made of alternating layers of pure lead sheet and lead dioxide slurry coated electrodes. Just scrape off the lead dioxide slurry, wash it in a solution of baking soda to neutralize any acid, and then dry the powder. It will probably dry into a hard cake, but it's easily crushed back into a fine powder.

Before I received my chlorinator anode, I toyed with the idea of mixing lead dioxide powder and epoxy adhesive with limited success. I was able to make a solid rod with decent mechanical strength, but the resistance was quite high from end to end (~100-200k ohm). This would mean excessive plating times until that first thin layer had been deposited.
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[*] posted on 9-2-2007 at 08:35


ok ill try that. i knew it but i kinda worry about cutting a battery .. i really don't want to find myself full with lead dioxide.
btw. is it possible to coat stainless steel with PbO2?
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[*] posted on 9-2-2007 at 08:56


I also cut a battery and its not as impossible as vou think of it.
You just have to suck up the sulphuric acid and then wash the inside of the battery with much water. Then it´s very easy to cut the lead and lead dioxide anodes out of the battery.
But be careful, the lead and lead dioxide at the anodes isn´t pure lead, theres a kind of glass fibre mixed with it.
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[*] posted on 9-2-2007 at 10:30


Electroless silver plating like is used for silvering mirrors
could be used to lay down a conductive surface on
a ceramic rod , like those alumina rods that are used for sharpening knives . Then the PbO2 could be electroplated onto the silver . Also there are unglazed
terra cotta patio tiles that are a foot square and perhaps 3/8" thick , and maybe a 1" wide strip of that material
could be scored and broken off , or cutoff using a tile saw , and the strip of terra cotta could be used as a
substrate .
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[*] posted on 9-2-2007 at 19:02


Quote:
Before I received my chlorinator anode, I toyed with the idea of mixing lead dioxide powder and epoxy adhesive with limited success. I was able to make a solid rod with decent mechanical strength, but the resistance was quite high from end to end (~100-200k ohm). This would mean excessive plating times until that first thin layer had been deposited.


Hello,

I am surprised that the rod conducted at all. I tried this a long time ago and it was hopeless. The rod was a good insulator. What epoxy did you use? If you could compress the paste around a conductive rod (carbon) this would eliminate some of the resistance. It would be an easy anode to make. Would it last long???? I suppose there is only one way to find out.
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[*] posted on 9-2-2007 at 19:13


Quote:
Originally posted by Rosco Bodine
Electroless silver plating like is used for silvering mirrors
could be used to lay down a conductive surface on
a ceramic rod , like those alumina rods that are used for sharpening knives . Then the PbO2 could be electroplated onto the silver . Also there are unglazed
terra cotta patio tiles that are a foot square and perhaps 3/8" thick , and maybe a 1" wide strip of that material
could be scored and broken off , or cutoff using a tile saw , and the strip of terra cotta could be used as a
substrate .



A problem with ceramic substrates is the (Per)Chlorate travelling up the ceramic and corroding the connection when in use. This might not be as bad with terracotta, but terra cotta is fearly smooth and Lead Dioxide may be inclined to fall off. The advantage of a very rough (say Silicon Carbide sharpening stone) was that the Lead Dioxide adhered very well to the substrate. It attached itself to the substrate very tightly as it keyed into the surface roughness. But substrates like this conducted the salt solution very well too which made connections to Anode difficult to maintain.

If one could make Magnetite anodes easily they would be a good substrate to stick/plate Lead Dioxide to. The Magnetite is virtually uneffected by the (Per)Chlorate electrolite. (You wouldent need Lead Dioxide for making Chlorate on the Magnetite.) I don't know if Lead Dioxide will plate onto Magnetite. The Lead Dioxide/epoxy would be easily........if it worked!!!!
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[*] posted on 9-2-2007 at 22:25


I was thinking of the ceramic simply as a structural form upon which a massive PbO2 anode might be plated , being used as a cheap substitute rigid substrate for the alternative , which is tantalum rod or barstock .

The silver will convert to silver oxide , which like PbO2
is conductive and adherent ....the advantage for it being
that it is easily laid down chemically on a nonconductor
like a ceramic , or even glass .

Possibly the ceramic could be soaked in silver nitrate ,
then dipped into hydrazine sulfate solution to mirror out
dispersed silver in its pores to make it conductive .
The surface could be roughened , notched , even have
holes drilled in spots to provide anchorage for the
PbO2 layer which will be built up by later plating .

The anode connection can be made directly to the PbO2
using a silver wire or silver strip . Silver oxide corrosion forming at the surface junction will remain conductive . The porosity of the PbO2 could perhaps be reduced in the connection area using a silicone oil or vacuum grease , or perhaps by melted paraffin or fiberglass resin , linseed oil , ect. as a barrier against wicking .

Really when a massive PbO2 anode is the intention ,
the substrate material is somewhat irrelevant so long
as it is something rigid enough to reenforce the fragile
PbO2 and is not chemically attacked by the conditions
presented by the cell in operation , and ideally it would need a thermal expansion property near to the same as the PbO2 so it wouldn't crack and crumble from thermal
stresses during temperature changes .
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[*] posted on 10-2-2007 at 03:41


Hey,
I am really interested to plate PbO2 on a metal.
Anyone had any luck with Iron,Steel, Aluminum?
I mean a massive anode plated on a metal grid for strength and conductivity. so even if it will crack the metal grid will drive the current on.
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[*] posted on 10-2-2007 at 13:22


Quote:
Originally posted by hashashan
Hey,
I am really interested to plate PbO2 on a metal.

Then your choices are few . Tantalum , platinum ,
perhaps titanium ? but no conductive connection there
since the oxide which will form is a blocking diode junction
to current flow which would be in the direction making it the anode . It is the conductivity and the corrosion problems
which limits the choices greatly as to what can be used as a substrate on which to plate the PbO2 .
Quote:

Anyone had any luck with Iron,Steel, Aluminum?

For the PbO2 anode substrate in a perchlorate cell ? No .
Quote:

I mean a massive anode plated on a metal grid for strength and conductivity. so even if it will crack the metal grid will drive the current on.

The lead dioxide layer is not entirely impermeable , so
whatever substrate is used must have some resistance to
corrosion and erosion by the extreme oxidizing effect when
the cell is in operation . For a massive anode of PbO2 , the
electrical contact is made to the PbO2 itself , which carries the current through its mass , regardless of the substrate .
But still , the substrate must be dimensionally stable and
not corroded ....so that the massive structure of PbO2 is not cracked or crumbled away from the substrate reenforcing
it from underneath . So any surface scaling or blistering
or dissolution by chemical attack of the substrate which would change its dimensions would fracture the fragile and
brittle PbO2 layer adhering .....and this must not occur ,
or else the anode coating will disintegrate and fall away
from the substrate . There are *very few* materials which
are chemically inert enough to withstand the *powerful*
oxidizing conditions present upon and inside the anode
structure in a perchlorate cell , and which might then function
as a suitable substrate material .
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[*] posted on 10-2-2007 at 14:37


ok so gauging rods it is then :)
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[*] posted on 10-2-2007 at 15:29


Yeah a good old gouging rod , perhaps soaked in molten paraffin , or linseed oil , then roughened up a bit with
coarse sandpaper and plated with a 3mm layer of PbO2
is a good possibility . One thing extra I thought about
is perhaps winding a spiral around the outside of the
rod using some braided fluoropolymer fly fishing line ,
from bottom to top , and then doing an opposite direction
spiral wrap overlaying the first spiral wrap so as to create a spiral diamond grid sort of pattern . The idea
is that the outer spiral would have a bit of a gap space
under it , around which the PbO2 could buildup many
physical anchorage points , something like the pattern
of spiraling rebar used to reenforce round support columns made of concrete in earthquake areas . The
PbO2 would be embedded with a fluoropolymer webbing
stretched tight across the surface of the graphite substrate , so that even if it cracked in many places ,
it would not fall off in pieces because it is laced to the substrate , all around .
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[*] posted on 10-2-2007 at 17:46


Quote:
Originally posted by hashashan
Hey,
I am really interested to plate PbO2 on a metal.
Anyone had any luck with Iron,Steel, Aluminum?
I mean a massive anode plated on a metal grid for strength and conductivity. so even if it will crack the metal grid will drive the current on.



Hello,,

See
JES Vol.105, No. 2 (Feb. 1958) page 100.
Lead Dioxide Anode for Commercial Use

at
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

They mention plating Lead Dioxide onto Iron or just about any metal. The problem is that the plating solution turns more and more asicid as nitric acid forms. This attacks most metals in the bath. It wont attack the 'Valve' metals, like Ti, Ta, and others. If you want to plate Iron or Nickle, (and theses have been used to make massive Anodes using a wire as the starting point for growing the Anode) you must control the pH of the plating tank. PITB.

BTW what do you guys mean when you say a 'massive' Lead Dioxide Anode?
I use the term to describe an Anode that has no substrate (it will have a substrate when in the plating tank) when it goes into use in the (Per)Chlroate cell. For example, Anodes have been grown on Iron, the Iron then stripped away and the piece of Lead Dioxide left used as a (massive) Anode.
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[*] posted on 10-2-2007 at 18:01


Quote:
One thing extra I thought about
is perhaps winding a spiral around the outside of the
rod using some braided fluoropolymer fly fishing line ,
from bottom to top , and then doing an opposite direction
spiral wrap overlaying the first spiral wrap so as to create a spiral diamond grid sort of pattern . The idea
is that the outer spiral would have a bit of a gap space
under it , around which the PbO2 could buildup many
physical anchorage points , something like the pattern
of spiraling rebar used to reenforce round support columns made of concrete in earthquake areas . The
PbO2 would be embedded with a fluoropolymer webbing
stretched tight across the surface of the graphite substrate , so that even if it cracked in many places ,
it would not fall off in pieces because it is laced to the substrate , all around .




There is an Anode described in the patents somewhere that describes using a graphite substrate with a cloth sleve slid over the rod. The lead Dioxide than grows onto the Carbon and through the cloth, similar to what you describe. The author claims it wont crack.

Patents are very ofter put onto paper without rigorously testing the idea. It may work, it may not.

As far as I can find out, when plating metals with Lead Dioxide, the only metals that were suffessful in the long term were the 'Valve' metals and in order to make the Anode last a long time in the (Per)Chlorate cell you had to revert to coating the Valve metals with a Platinum group metal so as to stop an oxide layer from starting to form and isolating the metal from the Lead Dioxide when the Anode was used in the ( Per)Chlorate cell.

You could always plate a Platinum wire. Look on the Lead Dioxide layer as being protection for your precious Pt wire!

I have never had success with using a gouging rod as a substrate. The Anode always failed soon after it went into service. (10 minutes some times :mad:)
A piece of carbon that does work, according to a guy who make the Anode and used it many times, is a rod of carbon out of a large low voltage carbon zinc battery. I thing it is about 6 inches long. The battery was one cell only but was about the size of a 4 litre bucket. It might be called a lantern battery (in USA). I could never come accross one of them.

Dann2
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[*] posted on 10-2-2007 at 19:12


Graphite or carbon is used as the substrate for the GSLD type anode . I thought that was supposed to be fine and
had even been adopted for commercial use .

Evidently titanium can be used as a permanent rigid metal substrate for PbO2
.....only if it is plated with platinum for protection .

There is a flat braided polyester lacing tape that is used
for securing the electrical windings in motors . It is available
in many thicknesses and widths . An idea I have is along the lines on the cloth reenforced substrate for a carbon anode .
A saw cut slot could be made in the bottom of the carbon
rod , and then it could be plated with a thin layer of PbO2 ,
perhaps a half millimeter or less . Then a knot is tied in the end of the lacing ribbon and the ribbon is slipped into the
sawn slot and then pulled so that the knot seats on the
opposite outside end of the slot and anchors the lower end
of the spiral winding , laid down like a barber pole stripe ,
the edge of each winding abutting the next so that the
entire PbO2 coated carbon is wrapped all the way to the
top and the end cinched down and knotted there as well
to secure the entire winding . The plating on of more PbO2
is continued until the whole spiral wrap is permeated and
then covered completely . A massive structure of PbO2 is
not needed , as the total combined thickness of PbO2 would be perhaps 1.5 to 2 mm down to the carbon and much of that volume of material would be filled with the polyester
fiber substrate . One of these lacing ribbons is made from
a 50/50 blend of polyester and fiberglass which is what I
would recommend . If the polyester doesn't hold up well
in the perchlorate cell then probably the glass will .

http://www.breydenproducts.com/StatorLacingTapesAndCords.htm

[Edited on 11-2-2007 by Rosco Bodine]

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[*] posted on 11-2-2007 at 14:55


Hello,


The problem with patents is that they seem to make everything very simply and straight forward.
You so X followed by Y, then do Z and low and behold you have a long lasting, better than anything before device. It is not that simple in practice.

You can coat Ti with Lead Dioxide but all commercial Anodes have had (as far as I can make out) a coating of Platinum between the Lead Dioxide and the Ti. Thats not to say that you cannot make a successful Ti substrate Anode. How long will it last???. The commercial people did not seem to think they were lasting long enough and turned to protecting the Ti with Pt first. I know guys that have make Ti substrate anodes but how long they lasted I have never been told.
The commercial Anodes have to work for months and months without trouble, so perhaps I am inclined to aim too high. After going to the trouble of making an Anode it is annoying to see it fail after a forthnight.

The ultimate goal for myself was to try and get a process that would lead to a long lasting Anode that was easy to make from easily available materials. This has proved to be difficult.

Regarding coating Graphite. There are many grades of graphite. EDM Graphtie has many prices and densities. It has been suggested to me that the best types are the hardest and most dense. Gouging rods are (alas) low guality qraphite. I could never get them to last long in a cell. Perhaps it was something I was doing wrong.

There are a hugh amount of parameters like for example, pH'S, Lead Ion concentrations, temperatures, additives, acid concentrations, substrate pretreatments, current densities, power wave shapes, and more that have been suggested as being the best! This is especially true in the patents. It is difficult to sort the whole thing out and get something that worKs for you that is as simple and easy to do as possible.

The cloth around the Graphite seems a good idea to me. Try it an see how it goes.

With plating baths it is good to try and have plating conditions stable. If you decide to go with a 30C temp. try an maintain that temperature. Try and maintain the pH constant. This is not simply especially if you start with a highish pH. If you start with a ph of 3.5 the pH will start to fall rapidly as you plate as Nitric Acid forms. It may be better to start with a pH of say 1 (add Nitric Acid at start) and them the pH will not fall so rapidly. It is not easy to control pH by adding Lead compounds (Lead Carbonate say) as you plate. Addition of the stuff will cause bubbles/foaming and it is difficult to know how much to add. When pH was controlled (in articles that I have read) it was done in a seperate tank with pumps etc. Far too much trouble IMHO.

Dann2
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[*] posted on 11-2-2007 at 15:08


Quote:
Originally posted by Rosco Bodine
Graphite or carbon is used as the substrate for the GSLD type anode . I thought that was supposed to be fine and
had even been adopted for commercial use .

Evidently titanium can be used as a permanent rigid metal substrate for PbO2
.....only if it is plated with platinum for protection .

There is a flat braided polyester lacing tape that is used
for securing the electrical windings in motors . It is available
in many thicknesses and widths . An idea I have is along the lines on the cloth reenforced substrate for a carbon anode .
A saw cut slot could be made in the bottom of the carbon
rod , and then it could be plated with a thin layer of PbO2 ,
perhaps a half millimeter or less . Then a knot is tied in the end of the lacing ribbon and the ribbon is slipped into the
sawn slot and then pulled so that the knot seats on the
opposite outside end of the slot and anchors the lower end
of the spiral winding , laid down like a barber pole stripe ,
the edge of each winding abutting the next so that the
entire PbO2 coated carbon is wrapped all the way to the
top and the end cinched down and knotted there as well
to secure the entire winding . The plating on of more PbO2
is continued until the whole spiral wrap is permeated and
then covered completely . A massive structure of PbO2 is
not needed , as the total combined thickness of PbO2 would be perhaps 1.5 to 2 mm down to the carbon and much of that volume of material would be filled with the polyester
fiber substrate . One of these lacing ribbons is made from
a 50/50 blend of polyester and fiberglass which is what I
would recommend . If the polyester doesn't hold up well
in the perchlorate cell then probably the glass will .

http://www.breydenproducts.com/StatorLacingTapesAndCords.htm

[Edited on 11-2-2007 by Rosco Bodine]


It is not a good idea to stop the plating process and then start to plate again as there will be a risk of the second coating falling off. ie. not adhering to the first coat. Cannot remember where I read this but it definitely mentioned it in a artical I read. Since you are putting plastic rope into the Anode perhaps this does not apply so much. Polyester plastic will hold up to cell conditions.


http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

Nylon does not hold up. Will the rope/cord be too thick?
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[*] posted on 11-2-2007 at 15:46


There are some Ta bits for sale here if anyone is interested.

(WWW.TUNGSTEN.COM)

http://www.tungsten.com/mtsprod.html

See the 'orphan bin'
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[*] posted on 11-2-2007 at 16:54


The interrupted coating failing to resume is something
I could believe would be caused by oils from the hands
contaminating the surface as it is handled . But I think
probably wearing gloves would stop that problem .
And after the lacing is done , simply dipping the
assembly in acetone and allowing it to dry should
provide a clean and degreased condition ready for
continued plating . A dip in diluted nitric acid would
probably not hurt either before resuming the plating .

As for the resumed plating falling off , that wouldn't be possible having a cloth substrate embedded in the
layer formed during the resumed plating .

Are you using the added nickel and copper nitrate in the lead nitrate plating bath when you are plating your
PbO2 onto your carbons ? IIRC you can improvise this
additive by dissolving US nickel coins in nitric acid ,
since they are actually made of a copper and nickel alloy ,
though I don't recall if the proportions are correct .
Also there was a surfactant supposed to be used and
a very specific rate for the plating .

A threaded tantalum rod would make a good substrate
if you have $75 you would like to spend .

http://cgi.ebay.com/TANTALUM-SOLID-ROUND-THREADED-ROD-5-16-2...

[Edited on 12-2-2007 by Rosco Bodine]
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