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Old 12-09-18, 16:41
David Dunlop David Dunlop is offline
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Join Date: Feb 2006
Location: Winnipeg, MB
Posts: 3,384
Default 52-Set Electroplating

Thought I would take a break here to poll the collective wisdom of the MLU Group.

I will start by referencing back to Page 2 of this thread, Post #46, Photo 3. This is an interior shot of the ZE-11 Remote Supply cover. Of interest here is the nature of the interior finish that is visible.

My first thought was this finish was just another metallic looking paint, although what stood out with it was the extremely fine metallic powder that must have been used to make it. it does not look at all like the typical aluminum finish paints available today. Curiosity got the better of me eventually and I tested the surface of the finish with a multimeter and was very surprised to see how conductive it was. A closer inspection of the Remote Supply revealed the entire cover assembly AND the base assembly had this coating under the paint.

A closer look at the Remote Receiver Case revealed it too had a complete coating of this finish on it, covering the entire finished assembly, with the exception of the Grounding Post Screw on the lower rear right side. The finish paint was then applied to the case, reaching into it only two inches from the leading edge of the case. I have yet to see one in person, but strongly suspect the entire basic, sheet metal case assembly of the Carrier No. 4 for the 52-Set is also finished in this coating. The heavier metal parts of the Carrier Assembly, possibly not.

I am pretty certain this is an electroplated finish and have narrowed the possibilities down to three metals: cadmium, satin nickel and zinc. I am presently leaning towards the satin nickel finish. From what I have seen of 75 year old cadmium and zinc plated items, somewhere, to some degree, one can find traces of humidity induced oxidation of the metal. The finish on these 52-Set items is pristine.

Once the dust settles with the new school term at the University of Manitoba, I would like to take the Remote Supply cover over to their Chemistry Department and see if they might have a none destructive means of testing this finish to determine what metal it is. I will need to know since several holes drilled into the back of my Remote Receiver case will need to be repaired and I would like to then have the case replated to completely restore the original look before painting.

I have run across a few references to satin nickel plating being used on wartime electronic items intended for navy use and shiny nickel pated finishes show up quite regularly on valve covers in army equipment. Has anyone encountered written references to the use of a satin nickel electroplating on components of wartime wireless gear?

David
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