[High_Q]

The insulating material could be derivative of acetic acid. Acetate is in fact derivative of acetic acid.  I think what 3602 states could make sense, but that does not explain why mine forms much greater green pigmint around the ear hook.
 
Edit:  It is right under the ear hook where it changes color the most, I doubt it is sweat causing it.

 

[tinyman392]

Actually, this is kinda both physics and chemistry.  Here's what happens:

• Copper must be in a magnetic field...  How do you do this?  Connect the copper to electricity.  It will turn the copper into a week electromagnet.
• Water molecules are polarized, so the will naturally be attracted to your newly created electromagnet.
• Water and copper chemically bond to form Copper (II) Oxide.  It can also combine with carbon dioxide, but it's less likely since it's not polarized, so it's harder to do.
• Acetic acid from your skin seeps in through various openings and reacts with the Copper (II) Oxide to form the verdigris.
• Once this is done, the acetic acid cannot react with the verdigris, so it flows down the cable due to gravity.
• Once it is at a spot with Copper (II) Oxide, it will react once again.
• It repeats steps 5-6 over until the whole cable is green with verdigris.
• Once the whole process is done, the whole cable is green.  All the acetic acid can do now is flow to the bottom of the cable.

 
At least this is what I think is happening.  It forms around the earhook first due to the fact that it's closer to your ear which has acetic acid (which is also polar in some forms).  Also, in order for all that above to happen quickly (instead of years), they have to be running so the magnet forces can attract the water and acetic acid to cause oxidation and further oxidation from the acetic acid.  If the headphones don't run, or the cables don't have electricity running through them, then it won't work as well.

 

[Mad Max]

 
Quote:

It is curious to me that it would be from skin oil.  From personal experience with the Shure's, as I noted, the plastic fell apart.  However, what was exposed was bright shiny copper, it did not have any green at all. Shure did indicate the plastic was reacting to skin acids defused in skin oil which caused it to become rigid then crack under stress.  In my case, I used the cable for a while even though the housing split, and the copper never turned green, so while my skin could react with the plastic it did not with the copper (makes me not want to nibble my wife's ear any more... Blech).
 
Anyhow, my chemistry fails me here, but a few points:
 
1) I do have trouble believe skin oil could propagate through an entire 1m+ cable all the way from the ears, or that sufficient oil could transfer from the ear area, and further that if it did the process would be very slow, non-uniform, and in addition to starting by the ears, would also likely move up from the plug where they get handled the most...  
 
2) Is it possible that the clear housing is somehow more gas or moisture permeable than colored housings, or is this just nothing more than dye added to create the color?  
 
3) Is it possible that the extremely thin sheath for IEMs to keep weight and bulk down is the culprit, allowing gas and moisture to penetrate the housing?
 
4  It really would be interesting to find out if those having these troubles are in a humid climates.
 
Chemists in the house?
 

1)  Atoms do not sit still, even in a solid.  Electrons and atoms can move around quite a bit over time, allowing the chlorination or whatever of the metal to propagate through out an entire cable, from the outside in.  Electrical current helps.  =\
If there's a reaction pathway with low enough activation energy, they'll go for it.
 
2)  Depends.
 
3)  Possibly, unfortunately, someone else will have to chime in on that.
 
4)  Possibly.  As you said before, cables can last a very long time before much of the copper combines with oxygen, carbonate, sulfate, or chlorine.  Very well-made cables can last many, many years.  Oxidized copper leads to increased series resistance and inductance(?).  Integrated circuits especially dislike too much series inductance in a PCB's traces.  I think the increased resistance is often negligible, but the increased series inductance is the reason for mildly reduced sound quality as far as cables, I think.  The cable loses a bit of bandwidth, I speculate.

 

[3602]

Polarization has nothing to do with magnetism. If you have access to some insanely powerful magnets you will still find that water does jack around them. Why? Because I've been MRI'd, the MRI being a really powerful magnet, and my body made of 70% water.
Also the Château Frontenac roof panels stayed brown for many-a time before greening. I am more compelled to believe the acidity/reacting with the insulator thing.

 

[tinyman392]

Quote:

Polarization has nothing to do with magnetism. If you have access to some insanely powerful magnets you will still find that water does jack around them. Why? Because I've been MRI'd, the MRI being a really powerful magnet, and my body made of 70% water.
Also the Château Frontenac roof panels stayed brown for many-a time before greening. I am more compelled to believe the acidity/reacting with the insulator thing.

It won't attract the water in your body since the distance is way too far and the attraction force between water molecules.  What it can attract is free water molecules (molecules that aren't together, single water molecules that form in the air naturally).
 
What deeper intrigues me is that the plastic reacts with the skin's oils (acetic acid being one of them), so the skin's oils couldn't reach the cable before breaking the plastic since it needs to react with the plastic (breaking it) before reacting with the cable.  If there was a force forcing the acetic acid and water to the cable before the plastic (a magnetic one), it would explain why the cable goes first before the plastic most of the time (the poles of the newly formed magnet would be the top and bottom of the cable respectively (where it starts and terminates).  So the acetic acid would go to those spots first.

 

[Mad Max]

 
Quote:

Actually, this is kinda both physics and chemistry.  Here's what happens:

• Copper must be in a magnetic field...  How do you do this?  Connect the copper to electricity.  It will turn the copper into a week electromagnet.
• Water molecules are polarized, so the will naturally be attracted to your newly created electromagnet.
• Water and copper chemically bond to form Copper (II) Oxide.  It can also combine with carbon dioxide, but it's less likely since it's not polarized, so it's harder to do.
• Acetic acid from your skin seeps in through various openings and reacts with the Copper (II) Oxide to form the verdigris.
• Once this is done, the acetic acid cannot react with the verdigris, so it flows down the cable due to gravity.
• Once it is at a spot with Copper (II) Oxide, it will react once again.
• It repeats steps 5-6 over until the whole cable is green with verdigris.
• Once the whole process is done, the whole cable is green.  All the acetic acid can do now is flow to the bottom of the cable.

 
At least this is what I think is happening.  It forms around the earhook first due to the fact that it's closer to your ear which has acetic acid (which is also polar in some forms).

You will get pretty even oxidation of a cable regardless of the presence of gravitational force.  The reactions occur one after another, slowly creeping along the conductor's surface.  My Grado y-splitter had begun to oxidize near the plug  That thing is often lying flat as I rarely use it.  The conductors were almost completely black from the outside in, but only a couple of inches from the plug.  The plug itself had splotches of oxidation, so I cut away the plug and wiring until I reached bright, unoxidized copper and reterminated it.

 

[High_Q]

I did a check on inductance for a 65cm, 22 guage cable and it is  0.000000984H.  If you think this value would reduce the SQ of the cable, it's your call. Resistance is 0.0351871 ohms, and reactace is 0.006182394ohms

  These calculators are all over the net, if you want to look up values.
Quote:

 
4)  Possibly.  As you said before, cables can last a very long time before much of the copper combines with oxygen, carbonate, sulfate, or chlorine.  Very well-made cables can last many, many years.  Oxidized copper leads to increased series resistance and inductance(?). 
 
 
Integrated circuits especially dislike too much series inductance in a PCB's traces.  I think the increased resistance is often negligible, but the increased series inductance is the reason for mildly reduced sound quality as far as cables, I think.  The cable loses a bit of bandwidth, I speculate.

 

 

[tinyman392]

Quote:

 

You will get pretty even oxidation of a cable regardless of the presence of gravitational force.  The reactions occur one after another, slowly creeping along the conductor's surface.  My Grado y-splitter had begun to oxidize near the plug  That thing is often lying flat as I rarely use it.  The conductors were almost completely black from the outside in, but only a couple of inches from the plug.  The plug itself had splotches of oxidation, so I cut away the plug and wiring until I reached bright, unoxidized copper and reterminated it.

I was only trying to explain why it happens so fast and quickly and why it starts at the earhook and downward.  The best reasoning for this would be the magnetic forces.  If the acetic acid did form a small hole in the cable, then water reacted with the copper (must happen before it turns green; Wiki article that is on the previous page states that indirectly), then the acetic acid reacts with the copper again, then it'll turn green.

 

[Mad Max]

 
Quote:

I did a checked on inductance for a 65cm, 22 guage cable and it is  0.000000984H.  Resistance is 0.0351871 ohms, and reactace is 0.006182394ohms

  These calculators are all over the net, if you want to look up values.

lol  I meant increased series inductance due to oxidation and what not.
 

 

[Mad Max]

 
Quote:

I was only trying to explain why it happens so fast and quickly and why it starts at the earhook and downward.  The best reasoning for this would be the magnetic forces.  If the acetic acid did form a small hole in the cable, then water reacted with the copper (must happen before it turns green; Wiki article that is on the previous page states that indirectly), then the acetic acid reacts with the copper again, then it'll turn green.

Or the cable was "contaminated" from the start.
 

 

[tinyman392]

Quote:

 

Or the cable was "contaminated" from the start.
 

 
I'd hope it wasn't, but yes, that can also be a possibility. 
 
 

 

[High_Q]

To me, the numbers makes it seams like a short(negligable resistance) cable no matter what.

 Compared to the source and load.  Those values are sooooo small, oxidation or not it's not gonna matter compared to source and load.
 
Quote:

 

lol  I meant increased series inductance due to oxidation and what not.
 

 

 

[rroseperry]

If it's verdigris, and that seems the best explanation to me, it's only a surface effect. Just saying/

 

[tinyman392]

Quote:

If it's verdigris, and that seems the best explanation to me, it's only a surface effect. Just saying/

Yeah, it's just for looks, green cables are the new thing
 

 

[Uncle Erik]

It's not the same at all, is it? On a statue or antique copper decorative piece, the copper is a symbol of age, which usually increases the value. On an electronic component, it means more oxidized copper, less purity of the conductor, and possible worse conductive capability resulting in worse sound (I can't vouche for that, I just imagine that would happen.
 
You can't compare something with purely aesthetic meaning to something with pratical meaning, since in the former it's encouraged, and in the latter it's associated with deterioration of what it was purchased for - carrying an electrical signal.

First, I argue that cables are decorative pieces. At least the ones sold around here are.

Second, you're assuming that surface oxidation changes the electrical properties of a cable. How so? Do you have any citations?

I'm a fool for old electronics. I have quite a few, I restore them and I use them. Since it's been clearing 110° F daily down here, I've been using my old fans a lot. This afternoon I went through a 16" Emerson from 1922. Got the dust off and gave it a good oiling. I replaced the headwire and power cord some years back. But other electrical components in there have been oxidizing for almost 90 years. They're fine. If you think audio is different, I've left 50, 60 and 70 years of oxidation in old radios. They're also fine.

This is just a cosmetic issue.

Personally, I like weathered-looking old electrical stuff. You always get the "OMG UNSAFE!!!!1!!1!" reaction from people. But as long as the wires have sufficient insulation (I do like modern high-temperature wire with Teflon), the innards are in good shape (modern caps and resistors), and mechanicals are cared for (e.g. cleaning and oiling the fans), then the old stuff is quite safe to use. Maintaining aged, original finishes is just part of the fun.