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SkySeeker 9th October 2007 07:04 PM

ESL Diaphragm coating
 
I have been reading about coatings until I could stand the subject no more. Sigh.

Seems there is very little consensus out there and quite a few secrets :-(

Mind you, I do appreciate the effort that some people put in in finding a good solution for this problem, and I fully understand if they want to keep their secrets. Besides it is their right to do just that. And there is always the risk that some company would want to run off with the formula and patent it. Talk about scr*** the inventor!

So I have absolutely nothing against secrets!

Having said that, I prefer to use a public domain solution (if at all possible). I like the idea of being able to reproduce my efforts at some other time (or by someone else) without the problems of having a supplier going out of business, or being bound by a promise for confidentiality.

Thus the coating is reduced to the following possibilities that I know of:

1) Graphite rubbing
2) Nylon in methanol
3) Glue
4) Elvamide (possible sourcing problem, better to use option 2?)

How are the experiences with any of the above?
Which one seems best for quality and long term stability?
Are there more solutions (pun intended!) for this?

I_Forgot 10th October 2007 12:30 AM

A fast, easy commercial solution is called Licron.

I_F

MJ Dijkstra 10th October 2007 07:04 AM

Re: ESL Diaphragm coating
 
Quote:

Originally posted by SkySeeker
I
1) Graphite rubbing
2) Nylon in methanol
3) Glue
4) Elvamide (possible sourcing problem, better to use option 2?)



1) poor intermolecular adhesion: that's why graphite is used as a lubricant for doorlocks! Too low resistance for constant charge mode(even with an external resistance). Works only when rubbed in the micropores of Mylar very hard, but risk of particles falling off remains. Grey colour. Time labourous. Risk of contamination. Positive: cheap, readily available.

2) won't dissolve in methanol. Phenol has been used but it is very toxic. Lethal dose is around 1 gram for an adult person and absorption through skin requires very careful handling. The result is a poor HC-system which doesn't work as well in every esl.

3) Non toxic but the same problem as 2) as it is a very high resistance HC system. Properties are poorly documented and there are positive and negative experiences probably caused by its HC mechanism. You could give it a try.

4) Expensive HC system with no added advantages compared 3). In fact, buying the proper solvent makes it more complicated and much more expensive than 3). The claimed tribo-electric effect is a simple lie intended to increase sales. Forget it.

Licron: discussed many times before as I-forgot promoted this stuff for some reason many times before as well. Easy indeed but compromised.

SkySeeker 10th October 2007 07:34 AM

Thanks Martin-Jan, you pretty much summed-up/confirmed what I gathered from reading (too many!) articles and postings.

Thus reading between the lines, you would suggest to either use Calvin's formula or silberlot's solution.

I might well do that as I am pretty much fed up with the subject and am coming close to the point where I just want "something that works - for me".

Capaciti 10th October 2007 07:57 AM

Hi Sky seeker,

other commercials might work as well, but my experience with more than 200 Esl coated tells me:

use EC-Coating from Martin-Jan and be happy. If applied correctly it will work, or in other words, If your ESl won't work with it, you can be sure that there is another issue with, stator insulation, power supply, leakage of construction etc,etc........

So protect yourself from too many parameters not to be under control.

And the key for an appropriate coating is "oxidization" by oxygen. if you take a closer look to other coatings, most of them suffer from it, EC-Coating doesn't oxidize, means best longtime performance.

Capaciti

SkySeeker 10th October 2007 08:16 AM

Deleted in edit.

MJ Dijkstra 10th October 2007 08:26 AM

For ordering sent me a private mail

arend-jan 10th October 2007 09:42 AM

Re: Re: ESL Diaphragm coating
 
Hi Martin-Jan

Quote:

Originally posted by MJ Dijkstra

4) Expensive HC system with no added advantages compared 3). In fact, buying the proper solvent makes it more complicated and much more expensive
What do you mean by expensive? Methanol is dirt cheap (couple of euro per liter) and Elvamide is not expensive either.

Quote:

3). The claimed tribo-electric effect is a simple lie intended to increase sales. Forget it.
This I find interesting. Can you explain a bit more?


I've been using Elvamide for Quad ESLs because it's the closest to the original coating (or so they say). It works fine. Do you see any advantages in using a different coating for these speakers?

Finally, what is the resistance you get with your EC coating?

Thanks,
Arend-Jan

MJ Dijkstra 10th October 2007 11:23 AM

Re: Re: Re: ESL Diaphragm coating
 
Quote:

Originally posted by arend-jan
Hi Martin-Jan



What do you mean by expensive? Methanol is dirt cheap (couple of euro per liter) and Elvamide is not expensive either.



This I find interesting. Can you explain a bit more?


I've been using Elvamide for Quad ESLs because it's the closest to the original coating (or so they say). It works fine. Do you see any advantages in using a different coating for these speakers?

Finally, what is the resistance you get with your EC coating?

Thanks,
Arend-Jan



Elvamide is expensive if you realize that it requires almost zero effort to put a tiny little bit of elvamide in a little bag and send it cheaply in an envelope while the result is a high resistance HC-system not better than you can make yourself with much less money.
As quad uses protective mebranes to keep out dust out of the panels, you might get it working with elvamide. But from the several contributions on different forums, it seems not to work as well in every esl, especially not in the quad63. Quad too doesn't use a HC-system in their '63 and newer models. Neither does any other commercial esl producer as far as I know

Why tribo-electric coatings don't excist:
Tribos (greece) means rubbing. The effect describes the effect of rubbing two different materials on each others. When seperated one of the materials gained more electrons by stealing from the other. Depends on how good the molecules can keep their electrons in the outer orbitals. The effect is also dependent on surface charasteristics so the tribo-electric ranking is not absolute. A clear example of this effect is when you walk on low quality carpet and touch the doorhandle. You get shocked. Antistatic coatings are used to eliminate this effect. So if someone claims a tribo-electric coating you apparantly would have to rub it to get it working which is unlikely of course. So it sounds nice but it is not true.

Finally, EC-coating is 500 - 1000 Megaohms

arend-jan 10th October 2007 12:48 PM

Hi MJ,

Thanks for the info. As a sidenode to Elvamide, I do know that Quad Germany uses the Elvamide (or some other nylon) coating on their new (57QA, e.g. the remake) Quad ESL. So there probably is a good reason for the use of it on this speaker, maybe because of the really small DS spacing in the treble panel. But that's conjecture on my part.

Elvamide does indeed not work very well on the 63, I have no idea why. I believe that the 63 has a graphite mixture for coating.


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