Highly Polished wire????

As a former chemist/material scientist, I have done a lot of work with metals and electricity. From whatever has not been forgotten by me, I can say that polishing metals does change a component's electrical properties. This is easily seen via resistivity/conductivity. We often burnished our contacts(a pencil eraser or fiberglass brush can work well), and the differences were certainly measurable.

The way two materials mate together is a very esoteric thing. The overriding goal is to achieve what is referred to as an "ohmic contact". That is techobabble for saying that the two materials marry well. No two disimilar materials ever marry as well as the same material to itself.

Silver was always far better in making connections than gold, and silver alloys(platinum/silver or palladium/silver) were better than silver as time goes by. In fact, 45% silver/55% palladium has been used for about 80 years when it comes to REALLY critical connections(military, not audio). This alloy is able to very nearly achieve a TCR(temperature coefficient of resistance) of zero. Which means that when put through mil - spec testing, in this case measuring resistance over a range of -55C to +125C, the resistance almost does not change. And, that holds true over time/use/fatigue.

As far as how all of my useless experience translates to audio, that is a bit more complicated.

I will say that AudioQuest sure markets the importance of the surface quality of a conductor. But, I feel that the sonics of their cables are no more or less superior to anyone elses. They have always maintained that the music rides along a wire's surface, hence its importance. Theoretically, if that is true, doing away with the impurities(such as oxides and sulfides) on a wires surface would pay real dividends.

However, many a cable manufacturer asserts that what their cable offers is the key to good sound. Whatever that technology may be. Also, if Nordost's technique is being held up as the only way to produce a good sounding cable, then I certainly cannot buy into any of this argument.

While copper and silver do combine well(check out a phase diagram), the real reason copper wire is plated with silver is to make it last longer; economics. The long term effects of silver(or any material) coming in contact with another material is in question.

For example, current flow will cause silver to strongly migrate through soda lime glass. Think this is not a real world example? Well, many high end resistors(Vishay, Holco, etc.) are cermet(ceramic - metallic) in composition, using glass as their bonding mechanism. That glass can be made of anything, as electronic glasses are infinite in number. Hopefully, it isn't soda lime glass, but as it is dirt cheap, it is prevalent. The industry can show SEM(scanning electron micrograph) after SEM of silver migration through a conductor/resistor it is joined to.

From an audio perspective, I have heard Ray Kimber worry about the long term effects of silver plated copper. It was a degradation question, from what I remember. Both he and AudioQuest have always disparaged silver plated copper as sounding horrible; bright, irritating, splashy. Although, now I think AQ is selling a silver plated conductor. I guess whatever sells...

Personally, I believe that better sound can sometimes come about by using the same material from a cable's stem to stern. I have heard cables with silver plugs, solder, and wire, and the sound was quite special. Natural, smooth, grainless. Not that this is a do or die statement. There is no such thing in audio, or wire. And, I think, that is my real overall point.

Trelja,

I am very impressed with that post. So if you were to get some fine silver wire, would you polish it? With what and then how would you clean it after polishing. You wouldn't happen to have a SEM handy would you .. :-)

- Dan

I use to prep the surface of copper, zinc, brass, and magnesium. We would grind the surface because impurities have a tendency to rise to the surface when casting and rolling the metal. We needed an ultra pure surface so the plates could be used in photo etching. Any and I mean any impurtities or foriegn material that was left on the surface would screw the etch up.

We used silcon carbine and aluminum oxide sanding belts and we use to have to grind with oil because of the flamability of magnesium. We would then clean the surface with water spaying out of jets and a mild detergent. To much detergent would contaminate the surface and too little would not clean the oil off.

I have cast zinc by pouring it in a mold and I have cast tantilin and tungston by casting in a vacuume. The methods used has a huge effect of the purity and the characteristic of the metal. You also can trap other impurities like carbon and oxygen during the casting process.

The tantilin was for compacitors and all the metal I have worked with was always actually a mix of metals. This gave it its best electrical or etching qualities. It might only be one percent zinc in the copper but this all makes a huge difference.

Polishing contacts is different.

_-_-bear

Dan,

Thanks for the kind words. By the way, if you are interested in investigating the company where I once worked, check out their website:

http://www.electroscience.com/index.html

I was in R & D, and developed many products over the years, which I take a lot of pride in the fact that they are listed on the site as current products. My favorite part of the field was designing conductors and resistors. Some of our customers were Vishay, Dale, CTS, Sprague, Ohmite, NTK, Bosch - suppliers to the high end industry.

While most of the things I dealt with were precious metals, I am not a jeweler, so my ideas about polishing wire may be way off base. However, as I did quite a lot of wirebonding(you know, the hairlike connections in a microchip from the actual chip to the leads) and microwelding. So, I got to buy a lot of aluminum, silver, gold, and platinum wire. Which is probably the reason why I am so virulently opposed to expensive audio cables. Believe me, even when we pay $100/m for a silver interconnect we are absolutely being taken to the cleaners. If I told you how much I could put together a set of gold interconnects for, we would all be crying.

As I am not a jeweler, I come from a different perspective as to how suitable a material is for the purpose of polishing a wire for high end audio applications. I will say that the composition of jeweler's rouge should be ascertained so as to be able to best remove its residue from the wire.

Obviously, there is a danger in "fixing something that isn't broken". By that I mean that if a wire is in good condition from the get go, one could muck things up by going about this business. I would say there would be something to act as a carrier in the composition, such as a polymer and solvent vehicle(be they both natural or synthetic). Once those ingredients are known, I would be able to recommend how to remove whatever residue is left.

In terms of abrasives, zirconia(zirconium oxide), tungsten carbide, or alumina(aluminum oxide) would all seem fine. What is a surprise to most people is that metals are pretty soft, especially in comparison to ceramics(oxides, carbides, nitrides, etc.) But, in order to obtain the type of polish you would be after, one would have to cascade the grit of abrasive. Progressively moving to finer and finer grits. I know from metal and furniture polishing that 400 and 600 grits leave a very smooth finish. 600 grit would be better.

But, is sanding wire a good thing? I think the starting point of the wire is the most important factor. If one were to buy very high grade silver or copper, and its surface appeared good, leave it alone. Maybe just treat it chemically(acetone, xylene, a glycol ether acetate, etc.) to remove any organic matter which had accumulated via handling.

Finally, perhaps Kondo - san from Audio Note knows best. He developed a way to draw the silver wire through the diamond dies during the wire's manufacture which in his view sounds best. To him, like many people's view of the initial audio signal, things must be perfect from their inception, once lost, it can never be regained.

GOOD LUCK!