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  1. #21
    Mustafa Umut Sarac's Avatar
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    The article to be plated is the cathode in an electrolytic bath with an anode as the other terminal.

    Chromium Plating

    Chromium plating is an electrochemical process in which a uniform layer of chromium is deposited on a cathode. In most plating operations, the anode is made of the material which is to be plated. But chromium plating is the exception because the anode is an inert lead alloy which merely supplies electrons to the solutions. These electrons react with the chromium in the solution to deposit on the cathode.

    Pure chromium anodes are too expensive and impractical to use.
    Early chroming from about 1933 or so seems to be shinier than later practice
    The quality of the chrome deteriorated during the last years of World War II and the early peace years, as Germany had a bad shortage of chromium, which is of course a strategic material. This was the reason behind the dark-grey cameras from the war years.
    Therefore, a lead or lead/antimony alloy is used and because of its inert properties, these anodes do not need to be replaced as often as other plating anodes.

    from web
    Umut

  2. #22
    Mustafa Umut Sarac's Avatar
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    For clarification , some points must be indicated. I am running two threads , here and Leica Forum and an heavy cannon as a moderator there confirmed that nickel interlayer between copper on brass and top chromium electro platings effects the chromes color and appereance.

    Is there anyway to measure each one of three layers thickness at a lab with sacrifying an lens cap ? How a lab person could to this , straching the cap and measuring the layers with an electron microscope ?

    Without going expenses , do anybody knows copper , nickel , chrome layers thicknesses in micron ?

    Umut

  3. #23
    Mustafa Umut Sarac's Avatar
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    I think Nondestructive Testing with Ultrasonic Inspection could yield a result but I dont know who can do that for ultra thin layers ?

    Umut

  4. #24
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    There is not one single plating thickness per layer that is used universally. I can tell you the chromium layer is usually very thin, compared to the nickel layer. I'm guessing it would not be more than 10 microns. It would be nice if it could be learned if the original plating was done to a standard industry specification, as is usually the case today. Then you could fairly easily duplicate it. I think it is unlikely, though.

    These days platers have a range of standard thicknesses they apply to meet different specifications and they can control those thicknesses well.

    I suggest you contact a plating shop there, where you live. They should be able to help you. It could be more effective for you to compare plating samples to your Leica than to determine your exact plating thicknesses through other methods. If necessary, they could plate some test pieces of brass for direct visual comparison. An experienced plater might have a good idea of thicknesses, just from examining the finish.
    But thickness is not everything. Electroplated nickel can vary in color significantly from a dull gray to a color resembling stainless steel. So, I would expect the specific plating information you now have to be of help to the plater to replicate the original color of the nickel interlayer.
    Also, something to consider: The older chrome processes usually used hexavalent chromium which is very toxic. Trivalent Chromium is less toxic and more common today, though hexavalent is still used. The trivalent is easier, and less expensive for the plater to use. It throws better, meaning it forms a more uniform layer, especially on inside corners or on intricate shapes. But its color is different. From what I understand, platers can modify trivalent chrome with additives to make it look like hexavalent chrome.


    An electron microscope could be used to determine thicknesses, if you have access to one. Even with that information, it will take some experimentation to replicate the original Leica finish.

    Also understand that as a satin chrome piece is handled over time, it will look a little more shiny, as handling polishes the "peaks" while leaving the "valleys" the original finish. So to truly replicate an original satin chrome finish, the sample of the original finish must be an area that gets little contact.

    One last idea: maybe you could find someone who specializes in restoring old Leicas, who might already have the information you need, or have the ability to replicate the original finish.
    Last edited by lxdude; 09-17-2012 at 02:27 PM. Click to view previous post history.
    I do use a digital device in my photographic pursuits when necessary.
    When someone rags on me for using film, I use a middle digit, upraised.

  5. #25
    Mustafa Umut Sarac's Avatar
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    Thank you very much Lxdude , this was very informative.
    I found a company which is specialized on Boeing , Lockheed parts supplier and electroplating.
    I sent them a long mail. They are test lab and production facility located in Ankara. If I can get help from them , that would be great.
    Old Japanese Swordsmiths predict the alloy from metal color . I worked as an scanner operator and even 40 years master was not good enough to predict the CMYK of a spot on the drum.
    I think I must deal with educated people and test machines.
    But DAG and Kreutner could be the resource. This is very good idea.
    Do you have suggestions for repair persons to be contacted ?

    Umut

  6. #26
    Mustafa Umut Sarac's Avatar
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    Another interesting point,

    I have an 1954 FED 1g and interlayer is black. I dont know if there is an nickel layer but at portholes , there is lack of chrome but deep black layer. Is there a chance for that camera about lack of nickel or nickel and chromium peeled off together ?
    I will ask to a plater about the tones of nickel layer , may be I can order small samples if they consider me serious.

    Umut

  7. #27
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    I don't know who the Leica specialists are, so I suggest asking here on Apug and some other forums, like RFF. Also, there might be someone near you who is a specialist and could help you.

    On the Fed, it could be that it is only a chrome layer, with no nickel. It's also most likely that if a nickel layer was there and the plating peeled off, the nickel layer and chrome layer would have come off together. Chrome layers are thin and surprisingly porous, and don't usually separate from the interlayer. When chrome plating peels, it usually comes off the base metal, though I have seen the nickel layer separate from the copper layer, leaving the copper layer intact. That was on steel, which had been distorted by impact.
    Most plating layers fail from underneath because of poor adhesion or corrosion under the plating, or both. Layers can also fail from excessive flexing or distortion of the part. I think the loss of plating at the portholes is probably because of corrosion starting at the edge of the holes, where it can get under the plating.
    I do use a digital device in my photographic pursuits when necessary.
    When someone rags on me for using film, I use a middle digit, upraised.

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