Unknown capsule skinning material

[Potato Cakes]

Hello, Everyone,

I wanted to share an interesting discovery I had when I was troubleshooting an old G7 build. I had previously installed a Luke Audio CK12 type capsule which had the slate gray looking material as shown on their website. When I opened the microphone back up I could see the capsule was very dirty from years of sitting around so I proceeded to clean it as I have done before on other microphones. When I did, the material that was used for skinning grabbed my cotton swap as though it had glue on it and effortlessly tore off of the back plate. I am curious as to what this material is so I can avoid it in the future.

I did have another capsule from them (I believe) that appeared to have the same gold sputtered material as used on every other microphone I have built and after that one was installed along with fixing a number of build errors everything is now working.

Thanks!

Paul

 

[SubSpec]

Luke Audio does allot of platinum sputtering, so I'd venture that's what it is. Specifically it appears to be their LA-1E.

 

[Екатерина]

This color doesn't look wonderful. Platinum oxidation is indeed black, but the conditions are very strict. I don't think it's platinum sputtering, it's likely carbides, such as graphite

 

[k brown]

This color doesn't look wonderful. Platinum oxidation is indeed black, but the conditions are very strict. I don't think it's platinum sputtering, it's likely carbides, such as graphite

Graphite was my first thought, as well, though I've never heard of it's use on diaphragms before.

 

[Recording Engineer]

This color doesn't look wonderful. Platinum oxidation is indeed black, but the conditions are very strict. I don't think it's platinum sputtering, it's likely carbides, such as graphite

I’d imagine your first line of thought is more correct than your second. Luke Audio generally gears toward ultra-thin, where graphite has only had success so-far as diaphragms that is too thick for pro microphone use.

I remember when I read an article years ago about graphite being successful as a microphone diaphragm at something like 70-microns! I asked Allen if he’s ever played with graphite. He said they did a little when he was with Shannon Rhodes, but not much.

It seems people are really into diaphragm-cleaning nowadays. With everyone in love with vintage, you’d think we’d all being regularly blowing cigarette smoke into them instead! Ha!

 

[k brown]

I’d imagine your first line of thought is more correct than your second. Luke Audio generally gears toward ultra-thin, where graphite has only had success so-far as diaphragms that is too thick for pro microphone use.

I remember when I read an article years ago about graphite being successful as a microphone diaphragm at something like 70-microns! I asked Allen if he’s ever played with graphite. He said they did a little when he was with Shannon Rhodes, but not much.

It seems people are really into diaphragm-cleaning nowadays. With everyone in love with vintage, you’d think we’d all being regularly blowing cigarette smoke into them instead! Ha!

I was thinking more in terms of graphite deposited on Mylar.

______

On a side note, I'd suggest a very soft sable artist's watercolor brush as the initial tool to touch a diaphragm - not a cotton swab (especially a moistened one).

 

[Recording Engineer]

I was thinking more in terms of graphite deposited on Mylar.

Ah. And I wasn’t. Could be right, but I’d be surprised if it’s not just his regular platinum.

 

[Екатерина]

I’d imagine your first line of thought is more correct than your second. Luke Audio generally gears toward ultra-thin, where graphite has only had success so-far as diaphragms that is too thick for pro microphone use.

I remember when I read an article years ago about graphite being successful as a microphone diaphragm at something like 70-microns! I asked Allen if he’s ever played with graphite. He said they did a little when he was with Shannon Rhodes, but not much.

It seems people are really into diaphragm-cleaning nowadays. With everyone in love with vintage, you’d think we’d all being regularly blowing cigarette smoke into them instead! Ha!

Graphite film already has 12um and 8um, and the main reason they cannot be used smoothly on capsules is due to cost. Their cost is even more expensive than gold foil, let alone widely used aluminum foil

 

[Potato Cakes]

I was thinking more in terms of graphite deposited on Mylar.

______

On a side note, I'd suggest a very soft sable artist's watercolor brush as the initial tool to touch a diaphragm - not a cotton swab (especially a moistened one).

It was a dry cotton swab. I never had any issues with this before. The material was very sticky, so I don't believe a paint brush would have faired better.

If I do a deep clean, it's high percentage Isopropyl then two more rounds diluted with 100% distilled water. This process uses paint brushes but the last step uses a dry cotton swap.

Thanks!

Paul

 

[k brown]

Graphite film already has 12um and 8um, and the main reason they cannot be used smoothly on capsules is due to cost. Their cost is even more expensive than gold foil, let alone widely used aluminum foil

Most capsules are neither aluminum foil or gold foil; they are polyester film ('Mylar') microscopically sputtered with gold or aluminum.

Foils are solid metal.

 

[Екатерина]

Most capsules are neither aluminum foil or gold foil; they are polyester film ('Mylar') microscopically sputtered with gold or aluminum.

Foils are solid metal.

Usually it is PET or PI, magnetron sputtering or evaporation plating process. The aluminum foil or gold foil I mentioned is only the conductive layer material plated on it, with an overall thickness between 10um~3um,

 

[k brown]

Usually it is PET or PI, magnetron sputtering or evaporation plating process. The aluminum foil or gold foil I mentioned is only the conductive layer material plated on it, with an overall thickness between 10um~3um,

PET IS polyester.

The term 'plating' is generally reserved for much thicker layers; 'sputtering' is the preferred and far more oft-used term for the mic diaphragm process.

 

[Recording Engineer]

Graphite film already has 12um and 8um, and the main reason they cannot be used smoothly on capsules is due to cost. Their cost is even more expensive than gold foil, let alone widely used aluminum foil

Where can I get this? More expensive? Fine. But how much more?

 

[Екатерина]

Where can I get this? More expensive? Fine. But how much more?

This may have to go to China, where the Russian mobile phone factory obtained it for use in mobile phone cooling systems. In Jiaxing, Zhejiang, 12um can be purchased for retail, and 8um can be purchased in large quantities. 12um costs $600 per square meter, which is very expensive. I gave up on them

 

[mjmajilton]

Luke can reskin it for you.

 

[SubSpec]

It feels like a case for Occam's Razor. That said, I was curious if any household materials might aid in finding an answer and according to CGPT hydrogen peroxide may:

Platinum catalyzes the decomposition of hydrogen peroxide into water and oxygen gas, causing bubbling. Graphite does not have this property.

• How to test:
  
  • Drop a small amount of 3% hydrogen peroxide onto a non-damaged area of the film.
  • Results:
    
    • If it’s platinum, you should observe immediate and vigorous bubbling.
    • If it’s graphite, there will be no reaction.