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Precautions for M6 Zinc top-plate


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When I purchased my Leica M6 classic there were scratches on the side as the strap's plastic thingy hits there all the time. As you can see you can see the zinc layer (silvery shiny). But now I am a bit worried about if it triggers an galvanic reaction on the top plate and it will turn into zinc oxide powder. 

 

Is there any suggestions to keep it in a good shape? I was thinking to cover it with a small piece of electrical tape. 

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Tom Abrahamsson:

 

QuoteQuoteQuote

 

The Zinc is not bad; it absorbs and dissipates impact fairly well. If you hit it really hard it can crack, but a brass housing hit with the same force, would have collapsed and crushed the finder assembly and metering circuitry. The biggest risk with using zinc is if you manage to scratch through the coating (chrome/black chrome. nickel and acid copper sealer) into the zinc itself. If you expose the "wound" to very salty air (sea spray, East Coast salted road slush) you can create a galvanic effect and the zinc will turn into a white powder and the plating will lift off. This being said, I have never had that happen to any of my M6's or late M4-P's, and they have not been babied over the years either and I do live less than 150ft/50meters from the Pacific Ocean

 

 

Other than that, the Zinc corrosion we see on M6 tops is in the shape of little bubbles under the chrome, caused by impurities in the Zinc, so it will not be influenced by external factors.

Personally I would use a bit of metal varnish and wipe it off, so that it would remain in the scratches.

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Tom Abrahamsson:

 

Other than that, the Zinc corrosion we see on M6 tops is in the shape of little bubbles under the chrome, caused by impurities in the Zinc, so it will not be influenced by external factors.

 

 

Other than these scratches it is perfectly fine. 

 

I will try metal varnish for sure, thanks!

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YES!

 

Those little scratches will never cause corrsion!

Take them as sihns of correct use.

Thomas

 

p.s.: never ever saw corrosion on the sides, where the strap's plastic moved against camera's edges! Only on top plate in very rare cases.

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Thanks guys! I am so relieved. 

 

I am collecting coins for years and the worst ones (in terms of preserving the UNC condition) are the German zinc coins from WWII era. Somehow they continue oxidise in archival quality, airtight holders. The idea of seeing something like this on my camera was devastating. 

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If you care to try it, there is a transparent wrap for the Leica available on the 'Bay. Search there for 182020169048.

 

I tried it, but am such a klutz I got only half of it on.

 

 

I don't trust myself on these kind of things :D :D :D 

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As has been pointed out, the scratches are only down to the nickel plating under the black anodising (there is no such thing as black chrome) so no problem. You will have to go some to get down to the zinc alloy top plate.

Are you sure about that?

 

http://www.arlingtonplating.com/capabilities/black-chrome-plating/

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In the context of Leica cameras I believe that I am correct. As I understand it Leica uses a black Eloxal process i.e. Black Anodising. Well that's what the factory at Solms quoted anyway. I believe that "Black Chrome" is more to do with the automotive industry.

I stand to be corrected by anyone out there who knows a lot more than me about plating of metals. Whatever the finish is, it is very hard wearing.

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My M6TTL is worn down to the bare zinc at several spots (strap, under the advance lever, rewind knob..) and its been out in the rain, sun, snow etc..

so far it didn't turned to powder.. :D

 

Isn't top plate made out of brass in TTLs???

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You have a loooong way to go before you get to the zinc.

 

My M6 is very worn, you can see the layers in parts. I've never noticed any corrosion or powder and I don't baby it, it's been covered in sea spray many times through the years, and been rained on countless times, and I sweat a bit. I don't abuse it either despite the look.

 

http://www.l-camera-forum.com/topic/254423-what-is-underneath-an-m6-classic-finish/?p=2949689

 

Cheers,

Michael

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As I understand it Leica uses a black Eloxal process i.e. Black Anodising. Well that's what the factory at Solms quoted anyway.

 

Eloxal is anodisation which applies to Aluminium only - Leica top plates were not (until recently) made from Aluminium so Black Chrome is applied as the black finish to black cameras unless they were Black Paint versions(see also: http://holzapfel-group.com/en/surfaces/decorative-surfaces/black-chrome.html). The finish is apparently applied onto a Nickel coating which itself is applied to the base (brass or Zinc). Eloxal is a superb and sometimes hardwearing finish - some underwater housings use it - but only available on Aluminium.

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