[ARC5] [Milsurplus] roller inductors
Richard Knoppow
1oldlens1 at ix.netcom.com
Tue Jan 26 17:32:42 EST 2016
This has been beaten to death but I want to mention one thing. It
was stated that silver sulfide is much more prevalent than silver oxide
as a tarnish. Perhaps in some cases, however, oxides such as nitrogen
oxide, are a very common pollutant. In black and white photographic
images on silver film or paper (the most common conventional kind) both
sulfiding and oxidation of the image takes place. Sulfiding can come
from residual processing chemicals, particularly fixing baths, but
oxidation is entirely from atmospheric pollution. Oxidation is
responsible for the "mirroring" effect sometimes seen on old prints.
The oxides migrate to the surface of the emulsion where some of them may
be reconverted to metallic silver. Otherwise they have a dark blue
color. Sulfiding is usually manifest as a yellow stain or fading.
Until about the mid-1960s the accepted method for providing archival
permanence of images was to remove absolutely all residual thiosulfate
(fixer) from the film or paper. This entailed very long washes and the
use of hypo clearing agents of various sorts. About 1961 research at
Kodak Research Laboratories found that the pure silver images resulting
from this processing method were extremely vulnerable to atmospheric
oxides. They also found that material washed only to commercial rather
than archival standards were much more resistant to the pollutants.
This was such heresy that Kodak was reluctant to publish it until
similar findings from Fuji's lab substantiated it. Kodak then revised
their processing recommendations. It turned out that a very small
residue of thiosulfate in the emulsion caused a slight sulfiding of the
silver crystals, which protected them from further sulfiding or
oxidation. A treatment in a sulfiding bath will provide nearly
complete protection to images as will a treatment in a gold toner.
However gold is expensive so microfilm and other materials where
permanence is important are usually treated in a polysulfide toner,
which is about as effective and much less costly.
This has little to do with electrical conductivity but the point is
that both silver sulfide and silver oxide can form on unprotected silver
surfaces.
For those interested much of the work on photographic permanence
was done at Kodak Research Laboratories, Fuji Film Labs and at the Image
Permanence Institute of the University of Rochester. Much of this data
is on line.
I did some searching around for more on the relative conductivity
on silver sulfide and silver oxide. No plain numbers but much academic
research. It would appear that the conductivity of both is affected by
all sorts of factors so there is probably not a single value for them.
On 1/26/2016 9:29 AM, Dennis Monticelli wrote:
> Yes, but very slowly and only if silver plate.
>
> BTW, silver plated utensils and platters are of value unless
> collectable. It costs about the same to extract the plating as the
> metal's value. I learned this lesson while trying to market a
> relative's silver plated items on their behalf.
>
> Dennis AE6C
>
>
>
> On Tue, Jan 26, 2016 at 8:52 AM, J Mcvey <ac2eu at yahoo.com
> <mailto:ac2eu at yahoo.com>> wrote:
>
> SO the act of cleaning Grandma's silver set is actually destroying it?
>
>
>
> On Monday, January 25, 2016 10:34 PM, Bill Carns
> <wcarns at austin.rr.com <mailto:wcarns at austin.rr.com>> wrote:
>
>
> It should be noted regarding these instructions to “Clean off the
> oxide” with Deoxit on the roller inductor, that silver tarnish is
> NOT an oxide, but a Sulfide. Silver Sulfide is CONDUCTIVE and is
> not the reason that the contacts are bad somewhere. Using any
> cleaner may also remove dirt and other contamination and Deoxit is
> as good as several others at doing this. I would use the DL100
> Deoxit that does not have a small percent lubricant as does the D5
> Deoxit. It is best to not leave any lubricant or anything at all
> on the contact.
> Many use just lab grade Isopropyl Alcohol for a cleaner. I use
> both and they both seem to work equally well.
> The following post in the thread after the Deoxit advice that
> suggest that the problem could be, and probably is, related to the
> follower spring contact on the contact bar is worth pursuing.
> While polishing the heck out of those roller contact areas may
> make you feel good, and it sure looks nice, it is a fool’s errand
> for the following reason. There is Sulphur in the atmosphere..
> Some environments have it more than others. That is why your
> mother’s Silver tarnishes. When the Silver Sulfide forms, it uses
> up (eats up) a monolayer or two of Silver. The Silver Sulfide is
> more or less self-limiting. Once a layer of the Sulfide forms, it
> way slows down the process. When you shine it up, you remove all
> the Sulfide – which includes that Silver Plate monolayer – and the
> process starts all over again – at high speed… and the Silver
> plating gets thinner and thinner. This is not desirable.
> So, clean all the contaminants off the roller coil with either
> Deoxit or Isopropyl and then look for the other causes that may be
> there as suggested.
> By the way, do not even think about using Silver Polish.. That is
> a disaster – especially Tarnex or similar acidic processes.
> Bill
> *From:*Milsurplus [mailto:milsurplus-bounces at mailman.qth.net
> <mailto:milsurplus-bounces at mailman.qth.net>] *On Behalf Of *Dennis
> Monticelli
> *Sent:* Monday, January 25, 2016 4:24 PM
> *To:* Joe Munson <prc74b at fuse.net <mailto:prc74b at fuse.net>>
> *Cc:* ARC-5 List <arc5 at mailman.qth.net
> <mailto:arc5 at mailman.qth.net>>; Milsurplus
> <Milsurplus at mailman.qth.net <mailto:Milsurplus at mailman.qth.net>>
> *Subject:* Re: [Milsurplus] [ARC5] roller inductors
> Joe,
> I presume you are dealing with silver plate. DeOxit is perfectly
> OK for removing the oxidation and not leaving behind a residue
> that is harmful to the inductor. That's a lot of surface area so
> be prepared for repeat applications.
> If you remove the inductor it's easier to deoxidize it. If
> completely removed you could also go the silver cream route and
> then wash completely afterwards.
> A coating of the Caig ProGold will keep the silver plate looking good.
> Dennis AE6C
> On Mon, Jan 25, 2016 at 1:41 PM, Joe Munson <prc74b at fuse.net
> <mailto:prc74b at fuse.net>> wrote:
>
> I have noticed on most of my surplus equipment using roller
> indctors, Command Sets, TCS, BC 191/375, Bendix TA 12,
> etc....all experience intermentent operation while moving the
> roller inductors with many dead spots. My questions to the
> group is how so porperely clean them. I know not to use
> DEOXIT, or other contact cleaners that leave a deposit. Years
> ago using Carbon TecnaChloride, (no longer available) seemed
> to do a fantastic job. I have tried the new style CRC
> electyric parts cleaners but seem to not work too well. I
> have wiped down the Rollers, the inductors, the roller shaft,
> the slip connectors, etcwith clean rags. . Still have
> intermentent operations. Any Ideas?
> Joe Munson
> WAVAG
> 513-919-1210
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net <mailto:ARC5 at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
> Please help support this email list:
> http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net <mailto:ARC5 at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20160126/50df8072/attachment-0001.html>
More information about the ARC5
mailing list