Hi gang,

I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. Trouble is they were stored in a damp environment and have that black coating on the copper. This is the form of Copper Oxide IIRC which forms when there's a limited supply of oxygen to the metal, as opposed to the green oxidisation you get on copper roofs and whatnot. So the question is, what commonly available chemical will attack the black oxide without damaging the copper underneath it? (Need to get it off before I solder the joints, obviously.)

cheers.

wrote in message
...
Hi gang,

I have some thick cables that need to be properly jointed. They're good for
300 Amps so pretty thick. Trouble is they were stored in a damp environment
and have that black coating on the copper. This is the form of Copper Oxide
IIRC which forms when there's a limited supply of oxygen to the metal, as
opposed to the green oxidisation you get on copper roofs and whatnot. So the
question is, what commonly available chemical will attack the black oxide
without damaging the copper underneath it? (Need to get it off before I
solder the joints, obviously.)

cheers.

You need an acid based flux and "tin" them with a high tin solder. (EG
Bakers fluid)
https://www.cromwell.co.uk/FRY8756015F
ISTR that hydrochloric acid was used for cleaning when oxidation was bad.
(Must be neutralised afterwards)
You will need a blowlamp for the tinning and ferrules for a soldered joint.
(Plus taped etc for insulating

You can get jointing kits but they usually have crimped joints and you need
the crimping tool (expensive)

Dependson what sort of cable it is.

"harryagain" wrote in message ...


wrote in message
...
Hi gang,

I have some thick cables that need to be properly jointed. They're good for
300 Amps so pretty thick. Trouble is they were stored in a damp environment
and have that black coating on the copper. This is the form of Copper Oxide
IIRC which forms when there's a limited supply of oxygen to the metal, as
opposed to the green oxidisation you get on copper roofs and whatnot. So
the question is, what commonly available chemical will attack the black
oxide without damaging the copper underneath it? (Need to get it off before
I solder the joints, obviously.)

cheers.

You need an acid based flux and "tin" them with a high tin solder. (EG
Bakers fluid)
https://www.cromwell.co.uk/FRY8756015F
ISTR that hydrochloric acid was used for cleaning when oxidation was bad.
(Must be neutralised afterwards)
You will need a blowlamp for the tinning and ferrules for a soldered joint.
(Plus taped etc for insulating

You can get jointing kits but they usually have crimped joints and you need
the crimping tool (expensive)

Dependson what sort of cable it is.

Citric acid would work well if you have some lemons to squeeze,
alternatively 'battery acid' ie sulphuric acid at about 2N concentration
will do the trick.

The day decimal coinage was introduced I was stranded in my Morris Minor,
when having to start it on the crank handle it back fired and shot the
handle out, with one of the lugs cutting a neat hole in the brass bottom of
the radiator miles from anywhere in Monmouthshire. I happened to have a
butane cylinder and torch, some plumbers solder, but not flux. I managed a
very serviceable repair soldering a 1 new penny coin over the hole using
acid from the battery, and having re-installed the radiator by the side of
the road continued my journey with VERY dirty hands. The girl friend at the
time was suitably impressed, but not enough to overcome the dirty hands

AWEM

On Thu, 8 Aug 2013 10:02:39 -0700 (PDT),
wrote:

I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. Trouble is they were stored in a damp
environment and have that black coating on the copper.

Stranded or solid? Is stranded how big are the strands? Can you not
just give 'em a quick rub with some fine wet 'n dry?

... the green oxidisation you get on copper roofs and whatnot.

That is copper carbonate, reaction between the copper and weak
carbonic acid (CO2 disolved in rain).

--
Cheers
Dave.

On Thursday, August 8, 2013 9:30:09 PM UTC+2, Dave Liquorice wrote:
On Thu, 8 Aug 2013 10:02:39 -0700 (PDT),

wrote:



I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. Trouble is they were stored in a damp

environment and have that black coating on the copper.



Stranded or solid? Is stranded how big are the strands? Can you not

just give 'em a quick rub with some fine wet 'n dry?



... the green oxidisation you get on copper roofs and whatnot.



That is copper carbonate, reaction between the copper and weak

carbonic acid (CO2 disolved in rain).


Thanks,
Yes, it's the worst case scenario: thumping thick cables comprised of scores of tiny, tiny strands - for flexibility I guess.
I had some Cilit Bang limescale cleaner spray hanging around and left a tuft of the affected cable to soak in it. After about half an hour, it had got rid of the black staining, but it still didn't look quite right. On closer inspection, the copper had attained a very non-metalic lustre the colour of salmon pink! Not quite sure what happened there. Looked promising to start with...
Never mind, I'll try some of the other suggestions here tomorrow.
I wonder if vinegar would be any good.....?

On Thu, 8 Aug 2013 15:08:57 -0700 (PDT),
wrote:

On closer inspection, the copper had attained a very non-metalic lustre
the colour of salmon pink!

Salmon pink is what copper looks like after acid attack. I think
you'll find that it will take solder with a decent flux. Try it...

This'll be a welding cable then, hefty but flexable. If you'd said
that in the first place I wouldn't have suggested wet 'n dry.

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.co.uk...

On Thu, 8 Aug 2013 15:08:57 -0700 (PDT),
wrote:

On closer inspection, the copper had attained a very non-metalic lustre
the colour of salmon pink!

Salmon pink is what copper looks like after acid attack. I think
you'll find that it will take solder with a decent flux. Try it...

This'll be a welding cable then, hefty but flexable. If you'd said
that in the first place I wouldn't have suggested wet 'n dry.


Also it's not usually advised to solder heavy multi-stranded welding cable.
The solder wicks up the strands stiffening the cable at the joint and
resulting in fracture at a future date. The normal received advice is to
crimp, or use on of the bolt together clamps designed for welding cables:

http://www.google.co.uk/imgres?start...&tx=57&ty=7 3

On 08/08/13 18:02, wrote:
Hi gang,

I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. Trouble is they were stored in a damp environment and have that black coating on the copper. This is the form of Copper Oxide IIRC which forms when there's a limited supply of oxygen to the metal, as opposed to the green oxidisation you get on copper roofs and whatnot. So the question is, what commonly available chemical will attack the black oxide without damaging the copper underneath it? (Need to get it off before I solder the joints, obviously.)

cheers.
any mild acid.

including flux.

but I prefer to draw the wire through fine emery paper

if its stranded use plumbers flux but wash it carefully afterwards


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 08/08/13 23:08, wrote:
On Thursday, August 8, 2013 9:30:09 PM UTC+2, Dave Liquorice wrote:
On Thu, 8 Aug 2013 10:02:39 -0700 (PDT),

wrote:



I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. Trouble is they were stored in a damp
environment and have that black coating on the copper.


Stranded or solid? Is stranded how big are the strands? Can you not

just give 'em a quick rub with some fine wet 'n dry?



... the green oxidisation you get on copper roofs and whatnot.


That is copper carbonate, reaction between the copper and weak

carbonic acid (CO2 disolved in rain).

Thanks,
Yes, it's the worst case scenario: thumping thick cables comprised of scores of tiny, tiny strands - for flexibility I guess.
I had some Cilit Bang limescale cleaner spray hanging around and left a tuft of the affected cable to soak in it. After about half an hour, it had got rid of the black staining, but it still didn't look quite right. On closer inspection, the copper had attained a very non-metalic lustre the colour of salmon pink! Not quite sure what happened there. Looked promising to start with...

that is cuprous oxide I think.

Never mind, I'll try some of the other suggestions here tomorrow.
I wonder if vinegar would be any good.....?



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Thursday, August 8, 2013 6:02:39 PM UTC+1, wrote:


I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. ....(Need to get it off before I solder the joints, obviously.)


Surely you should not be soldering a joint that is to carry a large current. Don't such joints have to be crimped?


Robert

On Friday, 9 August 2013 10:37:24 UTC+2, RobertL wrote:
On Thursday, August 8, 2013 6:02:39 PM UTC+1, wrote:





I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. ....(Need to get it off before I solder the joints, obviously.)





Surely you should not be soldering a joint that is to carry a large current. Don't such joints have to be crimped?





Robert

Depends how hot it's going to get, I would imagine. If the cable is specified for the current it's going to carry, it should *never* get hot enough to de-solder. However, I do take the point someone else made about such joints becoming prone to fracture over time...

On Friday 09 August 2013 09:37 RobertL wrote in uk.d-i-y:

On Thursday, August 8, 2013 6:02:39 PM UTC+1, wrote:


I have some thick cables that need to be properly jointed. They're good
for 300 Amps so pretty thick. ....(Need to get it off before I solder the
joints, obviously.)


Surely you should not be soldering a joint that is to carry a large
current. Don't such joints have to be crimped?


Robert

? Mains cables in the road used to be soldered - 1-2 sq inch conductors.

--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

On Friday, August 9, 2013 9:27:03 AM UTC+1, The Natural Philosopher wrote:

that is cuprous oxide I think.


otherwise known as copper oxide?

Jim K

Tim Watts wrote:
On Friday 09 August 2013 09:37 RobertL wrote in uk.d-i-y:

On Thursday, August 8, 2013 6:02:39 PM UTC+1, wrote:


I have some thick cables that need to be properly jointed. They're good
for 300 Amps so pretty thick. ....(Need to get it off before I solder the
joints, obviously.)


Surely you should not be soldering a joint that is to carry a large
current. Don't such joints have to be crimped?


Robert

? Mains cables in the road used to be soldered - 1-2 sq inch conductors.


Yeah but, they're not really designed to be very flexible or likely to be
flexed much once in situ.

Tim

In article ,
wrote:
Depends how hot it's going to get, I would imagine. If the cable is
specified for the current it's going to carry, it should *never* get hot
enough to de-solder. However, I do take the point someone else made
about such joints becoming prone to fracture over time...

The way round that is to support the cable some way from the joint.
Although crimping is the best way - but with the correct crimping tool,
not pliers. And those can be expensive.

--
*Change is inevitable ... except from vending machines *

Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, 9 August 2013 12:50:14 UTC+2, Chris Hogg wrote:
On Fri, 9 Aug 2013 02:51:21 -0700 (PDT), Jim K

wrote:



On Friday, August 9, 2013 9:27:03 AM UTC+1, The Natural Philosopher wrote:



that is cuprous oxide I think.





otherwise known as copper oxide?



Jim K



There are two oxides of copper: cuprous oxide aka cuprite, Cu2O, red,

and cupric oxide, CuO, black. Cupric oxide, heated to above about

1025C in air, loses oxygen and converts to cuprous oxide. Cuprous

oxide melts at 1235C.



--



Chris

What's the green ****e you find on old copper pipes and copper flashing on roofs, then?

wrote:

What's the green ****e you find on old copper pipes and copper flashing on roofs, then?

IIRC mostly it is hydrated copper carbonate. Rainwater absorbs CO2 from the
air and is mildly acidic (carbonic acid). It reacts with copper to form
verdigris which is mostly copper carbonate.

We don't get it at all in Italy, copper turns brown not green.

--
€¢DarWin|
_/ _/

On Friday 09 August 2013 11:35 Tim+ wrote in uk.d-i-y:

Tim Watts wrote:
On Friday 09 August 2013 09:37 RobertL wrote in uk.d-i-y:

On Thursday, August 8, 2013 6:02:39 PM UTC+1,
wrote:


I have some thick cables that need to be properly jointed. They're good
for 300 Amps so pretty thick. ....(Need to get it off before I solder
the joints, obviously.)


Surely you should not be soldering a joint that is to carry a large
current. Don't such joints have to be crimped?


Robert

? Mains cables in the road used to be soldered - 1-2 sq inch conductors.


Yeah but, they're not really designed to be very flexible or likely to be
flexed much once in situ.

Tim

Yes I agree. But the point I was contering was that "large current cables
should not be soldered" which is in itself not fundamentally true.

I'd solder the cables in question and provide support for 3+ inches either
side of the joint - possibly by potting inside a bit of tube or application
of several layers of adhesive heastrink. Depends how much flexing is
expected.
--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

On 09/08/13 09:37, RobertL wrote:
On Thursday, August 8, 2013 6:02:39 PM UTC+1, wrote:

I have some thick cables that need to be properly jointed. They're good for 300 Amps so pretty thick. ....(Need to get it off before I solder the joints, obviously.)

Surely you should not be soldering a joint that is to carry a large current. Don't such joints have to be crimped?


Robert

no.
the problem with soldering is not high current, it is the mechanical
stiffening which means that its very likely to fracture where the solder
stops..


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 09/08/13 10:51, Jim K wrote:
On Friday, August 9, 2013 9:27:03 AM UTC+1, The Natural Philosopher wrote:

that is cuprous oxide I think.

otherwise known as copper oxide?

Jim K
No that's cupric oxide.

Or at lest let'ssay there are two copper oxides, one red, one black, and
both may be referred to as copper oxide. Cuprous is the red one. Cupric
is the black one.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 09/08/13 13:39, wrote:
On Friday, 9 August 2013 12:50:14 UTC+2, Chris Hogg wrote:

There are two oxides of copper: cuprous oxide aka cuprite, Cu2O, red,

and cupric oxide, CuO, black. Cupric oxide, heated to above about

1025C in air, loses oxygen and converts to cuprous oxide. Cuprous

oxide melts at 1235C.

Chris
What's the green ****e you find on old copper pipes and copper flashing on roofs, then?
copper carbonate. Co2 in the air in the presence of water turns copper
oxides to copper carbonates.
Theres a few more copper salts that pop up too sulphates and acetates -
any weak acid will turn the oxide to a salt eventually.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Friday, 9 August 2013 15:34:59 UTC+2, Tim Watts wrote:
On Friday 09 August 2013 11:35 Tim+ wrote in uk.d-i-y:



Tim Watts wrote:

On Friday 09 August 2013 09:37 RobertL wrote in uk.d-i-y:



On Thursday, August 8, 2013 6:02:39 PM UTC+1,

wrote:





I have some thick cables that need to be properly jointed. They're good

for 300 Amps so pretty thick. ....(Need to get it off before I solder

the joints, obviously.)





Surely you should not be soldering a joint that is to carry a large

current. Don't such joints have to be crimped?





Robert



? Mains cables in the road used to be soldered - 1-2 sq inch conductors.





Yeah but, they're not really designed to be very flexible or likely to be

flexed much once in situ.



Tim



Yes I agree. But the point I was contering was that "large current cables

should not be soldered" which is in itself not fundamentally true.



I'd solder the cables in question and provide support for 3+ inches either

side of the joint - possibly by potting inside a bit of tube or application

of several layers of adhesive heastrink. Depends how much flexing is

expected.

A 6" spring to sheath the finished joint might be better. If one can stop it sliding out of position.

"Chris Hogg" wrote in message
...

On Fri, 09 Aug 2013 15:19:24 +0100, Tim Streater
wrote:


At our old house where the copper CH pipes went into the floor
(concrete) the pipes were stained green about a half-inch above the
cement. Why would it be occurring just there?

Dunno off hand. Mortar can be quite alkaline, and I would guess that
it's something to do with the alkalinity of the cement coupled with
straightforward oxidation of the copper. I've seen similar sort of
thing when solder flux is also involved, and I believe it's now good
practice to wrap all soldered joints in copper pipes with something
like Denso tape if they're going to be buried in concrete.

Having said all that, Googling for 'concrete attack copper' gives a
variety of answers, many of them saying that copper isn't attacked by
concrete.


Well actually copper pipe buried in concrete is attacked, but not
chemically, it's a physical effect. The ch pipes expand and contract as they
warm and cool, and the copper is abraded by the concrete. This is why the
advice is to sleeve the pipe before pouring the concrete.

AWEM

On 09/08/2013 14:27, Chris Hogg wrote:
On Fri, 9 Aug 2013 12:57:31 +0000 (UTC), Steve Firth
wrote:

wrote:

What's the green ****e you find on old copper pipes and copper flashing on roofs, then?

IIRC mostly it is hydrated copper carbonate.

+1

Pure copper carbonate, CuCO3, doesn't exist as such in the pure state,
but the green stuff is basic copper carbonate, CuCO3.Cu(OH)2,
malachite. There is also a bright blue form, 2CuCO3.Cu(OH)2, azurite.
Both occur in copper ores, and malachite can occur in sufficiently
large pieces for it to be made into jewellery or larger decorative
items. Look on e-bay for malachite to see some examples.

And see all that Southern Railway rolling stock in malachite green. :-)

http://www.ebay.co.uk/itm/HORNBY-R29...-/290871769013

--
Rod

On 09/08/13 15:19, Tim Streater wrote:
In article ,
Chris Hogg wrote:

On Fri, 9 Aug 2013 12:57:31 +0000 (UTC), Steve Firth
wrote:

wrote:

What's the green ****e you find on old copper pipes and copper
flashing on roofs, then?

IIRC mostly it is hydrated copper carbonate.
+1
Pure copper carbonate, CuCO3, doesn't exist as such in the pure state,
but the green stuff is basic copper carbonate, CuCO3.Cu(OH)2,
malachite. There is also a bright blue form, 2CuCO3.Cu(OH)2, azurite.
Both occur in copper ores, and malachite can occur in sufficiently
large pieces for it to be made into jewellery or larger decorative
items. Look on e-bay for malachite to see some examples.

At our old house where the copper CH pipes went into the floor
(concrete) the pipes were stained green about a half-inch above the
cement. Why would it be occurring just there?

best place for condensation.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Friday, 9 August 2013 22:49:10 UTC+2, polygonum wrote:
On 09/08/2013 14:27, Chris Hogg wrote:

On Fri, 9 Aug 2013 12:57:31 +0000 (UTC), Steve Firth

wrote:



wrote:



What's the green ****e you find on old copper pipes and copper flashing on roofs, then?



IIRC mostly it is hydrated copper carbonate.



+1



Pure copper carbonate, CuCO3, doesn't exist as such in the pure state,

but the green stuff is basic copper carbonate, CuCO3.Cu(OH)2,

malachite. There is also a bright blue form, 2CuCO3.Cu(OH)2, azurite.

Both occur in copper ores, and malachite can occur in sufficiently

large pieces for it to be made into jewellery or larger decorative

items. Look on e-bay for malachite to see some examples.



And see all that Southern Railway rolling stock in malachite green. :-)



http://www.ebay.co.uk/itm/HORNBY-R29...-/290871769013


Inspiring! I'm now on ebay trying to source a malachite coloured roller-neck jumper and some bright red flares to set it off.

On Fri, 09 Aug 2013 11:50:14 +0100, Chris Hogg wrote:

On Fri, 9 Aug 2013 02:51:21 -0700 (PDT), Jim K
wrote:

On Friday, August 9, 2013 9:27:03 AM UTC+1, The Natural Philosopher wrote:

that is cuprous oxide I think.


otherwise known as copper oxide?

Jim K

There are two oxides of copper: cuprous oxide aka cuprite, Cu2O, red,
and cupric oxide, CuO, black. Cupric oxide, heated to above about
1025C in air, loses oxygen and converts to cuprous oxide. Cuprous
oxide melts at 1235C.

....and copper melts at 1085 deg C
--