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The bezel on a watch I am repairing has nearly all the plating worn away.  With hours of searching I was only able to find one replacement NOS part, but as you can see in the picture it has a bit of tarnish. I’m not sure if it is rust, or some other type of issue, but hopefully one of you can shed some light on the matter. 

I placed the order and hopefully will have it in a week or two. It is simply just a gold plated part.  Do you believe this is rust, or some other type of finish degradation? My fear is that by whatever means I used to clean it I would also be removing the gold plating.

If you can provide any suggestions on how to restore the finish of this part without wearing away the plating I would appreciate it very much

Thanks. 
 

2E18FA56-832E-4268-B134-E2B6C3B3ABD7.thumb.jpeg.1b14dc97e4591d64ce1c2c169ff25dba.jpeg
 

17354A16-3EC8-46D6-BA7D-8F3CECCA6F60.thumb.jpeg.ffc2fcb78e40798d266a849ebbc6995e.jpeg

Edited by thor447
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It's hard to say.  Just as you don't know what the defect is, the answer is also unknown.  If it is "gold" that should not be tarnish or rust.  If it is, I would think that the plating is already gone.  If it's dirt or another type of deposit, your options open up.

Good luck.

Shane 

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1 hour ago, thor447 said:

The bezel on a watch I am repairing has nearly all the plating worn away.  With hours of searching I was only able to find one replacement NOS part, but as you can see in the picture it has a bit of tarnish. I’m not sure if it is rust, or some other type of issue, but hopefully one of you can shed some light on the matter. 

I placed the order and hopefully will have it in a week or two. It is simply just a gold plated part.  Do you believe this is rust, or some other type of finish degradation? My fear is that by whatever means I used to clean it I would also be removing the gold plating.

If you can provide any suggestions on how to restore the finish of this part without wearing away the plating I would appreciate it very much

Thanks. 
 

2E18FA56-832E-4268-B134-E2B6C3B3ABD7.thumb.jpeg.1b14dc97e4591d64ce1c2c169ff25dba.jpeg
 

17354A16-3EC8-46D6-BA7D-8F3CECCA6F60.thumb.jpeg.ffc2fcb78e40798d266a849ebbc6995e.jpeg

Hello @thor447,

When you get it, post better quality photos at the highest possible resolution.  Normally speaking, pure Gold (AU) does not normally "rust" (oxidize) as its molecular composition does not have spaces in its electron shell to be able to interact with Oxygen, which is the usual suspect when we talk about "rusting". 

There's simply nowhere for Oxygen to bind to  the typical complexes of Gold atoms:

image.png.5200b3a325870096f152136d0774d6b0.png


So, by definition, gold is a tough metal to oxidize - or even get to interact with anything else, which is why it's called a "noble" metal.  But it can be mixed with some other metals and it can be dissolved into a solution, but not by things we normally come into contact with in everyday life as they are quite corrosive (aqua regia) or toxic (cyanide), or high energy (smelting).

There's some reasonably good information in Wikipedia about gold that can help give you some background if you don't already know a bunch about it.  Personally, I find gold fascinating for its many uses:

https://en.wikipedia.org/wiki/Gold

When things are "gold plated" that means that an alloy of gold has usually been used, which is typically an amalgam of gold plus some other metal at various proportions of 1/24th.  So, the other metal(s) used to create that alloy may be what's oxidizing that ring - or it might be dirt, or something that dripped on the ring, or a product of some form of galvanic action because the ring got wet and touched something it shouldn't have.  It's hard to tell.

https://en.wikipedia.org/wiki/Galvanic_corrosion

As for polishing the stain(s) away...beware!  Plating is measured in microns, so it's super thin.  You might be able to get away with a delicate silver tableware style hand polish buffing cloth but even then some people on this forum might get tense.  Anything more abrasive than that (Silvo, cream silver polish) is almost certainly a no-no.  Mechanical polishing with buffing wheels and cutting or polishing compounds (rouge) is likely out of the question.

But all is not lost.  While you cannot put plating back on unless you want to go to the trouble of stripping and re-plating, which is a hassle and very time consuming, I did recently see Peter Grande use an applicator to selectively re-plate the gold plating on shoulders lugs that had been worn away.  I've seen people use this before - but I don't know how well that plating adheres over the long term in such a high-wear area as wristwatch lugs.  Considering the reasonably weak bond between plating and the base metal in general, I doubt it will last as long as a total re-plate because fully plated pieces offer no purchase point (seam) for mechanical detachment to begin.

g.
----

Disclosure:  I worked in a gold mine for two years to make enough money to pay for University.  Over the past 20 years, I have consulted extensively to the the Jewelry industry in Hong Kong in terms of both Design and Fabrication.  One of the subject areas I teach in at HKPU touches on the topics of Precious Stones and Precious Metals in our Jewelry Design stream, which is incorporated in our Fashion Design Undergraduate Program.  Hong Kong is a jewelry and watchmaking center, and we have many hundreds of graduates working in the Jewelry industry in Asia.

 

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58 minutes ago, Gramham said:

Hello @thor447,

When you get it, post better quality photos at the highest possible resolution.  Normally speaking, pure Gold (AU) does not normally "rust" (oxidize) as its molecular composition does not have spaces in its electron shell to be able to interact with Oxygen, which is the usual suspect when we talk about "rusting". 

There's simply nowhere for Oxygen to bind to  the typical complexes of Gold atoms:

image.png.5200b3a325870096f152136d0774d6b0.png


So, by definition, gold is a tough metal to oxidize - or even get to interact with anything else, which is why it's called a "noble" metal.  But it can be mixed with some other metals and it can be dissolved into a solution, but not by things we normally come into contact with in everyday life as they are quite corrosive (aqua regia) or toxic (cyanide), or high energy (smelting).

There's some reasonably good information in Wikipedia about gold that can help give you some background if you don't already know a bunch about it.  Personally, I find gold fascinating for its many uses:

https://en.wikipedia.org/wiki/Gold

When things are "gold plated" that means that an alloy of gold has usually been used, which is typically an amalgam of gold plus some other metal at various proportions of 1/24th.  So, the other metal(s) used to create that alloy may be what's oxidizing that ring - or it might be dirt, or something that dripped on the ring, or a product of some form of galvanic action because the ring got wet and touched something it shouldn't have.  It's hard to tell.

https://en.wikipedia.org/wiki/Galvanic_corrosion

As for polishing the stain(s) away...beware!  Plating is measured in microns, so it's super thin.  You might be able to get away with a delicate silver tableware style hand polish buffing cloth but even then some people on this forum might get tense.  Anything more abrasive than that (Silvo, cream silver polish) is almost certainly a no-no.  Mechanical polishing with buffing wheels and cutting or polishing compounds (rouge) is likely out of the question.

But all is not lost.  While you cannot put plating back on unless you want to go to the trouble of stripping and re-plating, which is a hassle and very time consuming, I did recently see Peter Grande use an applicator to selectively re-plate the gold plating on shoulders lugs that had been worn away.  I've seen people use this before - but I don't know how well that plating adheres over the long term in such a high-wear area as wristwatch lugs.  Considering the reasonably weak bond between plating and the base metal in general, I doubt it will last as long as a total re-plate because fully plated pieces offer no purchase point (seam) for mechanical detachment to begin.

g.
----

Disclosure:  I worked in a gold mine for two years to make enough money to pay for University.  Over the past 20 years, I have consulted extensively to the the Jewelry industry in Hong Kong in terms of both Design and Fabrication.  One of the subject areas I teach in at HKPU touches on the topics of Precious Stones and Precious Metals in our Jewelry Design stream, which is incorporated in our Fashion Design Undergraduate Program.  Hong Kong is a jewelry and watchmaking center, and we have many hundreds of graduates working in the Jewelry industry in Asia.

 

Goodness, thank your for taking the time to type out all of that information.  I, along with others I'm sure, certainly appreciate it.  When the part arrives I will take some high resolution photographs and post them to the forum.  In the meantime, I will try to research alternative methods, including what you described in your reply.  Thanks again.

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4 hours ago, thor447 said:

The bezel on a watch I am repairing has nearly all the plating worn away.  With hours of searching I was only able to find one replacement NOS part, but as you can see in the picture it has a bit of tarnish. I’m not sure if it is rust, or some other type of issue, but hopefully one of you can shed some light on the matter. 

I placed the order and hopefully will have it in a week or two. It is simply just a gold plated part.  Do you believe this is rust, or some other type of finish degradation? My fear is that by whatever means I used to clean it I would also be removing the gold plating.

If you can provide any suggestions on how to restore the finish of this part without wearing away the plating I would appreciate it very much

Thanks. 
 

2E18FA56-832E-4268-B134-E2B6C3B3ABD7.thumb.jpeg.1b14dc97e4591d64ce1c2c169ff25dba.jpeg
 

17354A16-3EC8-46D6-BA7D-8F3CECCA6F60.thumb.jpeg.ffc2fcb78e40798d266a849ebbc6995e.jpeg

Difficult to say from the photos if the discolouration is on the surface or underneath.  Hopefully it is surface , depending how thick the plating is how much polishing it will take. Start off gently with a dry microfiber cloth,  if this is not enough then a light metal polish like brasso is not especially abrasive. Solvol is more so, i often use this on plated cases with good results though. A good plating will withstand a light machine buff with a high grit compound. I haven’t managed to wear though a plating with a buffing pad as yet and the results are usually very good. Watch some of the nekkid watchmaker's videos. Joe is bloody good at case restoration,  it will give you an idea of how much a plating can take. Generally a 10 micron plating is pretty tough and will take some machine buffing. 

9 minutes ago, Neverenoughwatches said:

Difficult to say from the photos if the discolouration is on the surface or underneath.  Hopefully it is surface , depending how thick the plating is how much polishing it will take. Start off gently with a dry microfiber cloth,  if this is not enough then a light metal polish like brasso is not especially abrasive. Solvol is more so, i often use this on plated cases with good results though. A good plating will withstand a light machine buff with a high grit compound. I haven’t managed to wear though a plating with a buffing pad as yet and the results are usually very good. Watch some of the nekkid watchmaker's videos. Joe is bloody good at case restoration,  it will give you an idea of how much a plating can take. Generally a 10 micron plating is pretty tough and will take some machine buffing. 

Just to add to this Thor.  The bezel on its own will be relatively flimsy so any over enthusiastic polishing may distort it. To be on the safe side mount it on the empty case first.

4 hours ago, thor447 said:

The bezel on a watch I am repairing has nearly all the plating worn away.  With hours of searching I was only able to find one replacement NOS part, but as you can see in the picture it has a bit of tarnish. I’m not sure if it is rust, or some other type of issue, but hopefully one of you can shed some light on the matter. 

I placed the order and hopefully will have it in a week or two. It is simply just a gold plated part.  Do you believe this is rust, or some other type of finish degradation? My fear is that by whatever means I used to clean it I would also be removing the gold plating.

If you can provide any suggestions on how to restore the finish of this part without wearing away the plating I would appreciate it very much

Thanks. 
 

2E18FA56-832E-4268-B134-E2B6C3B3ABD7.thumb.jpeg.1b14dc97e4591d64ce1c2c169ff25dba.jpeg
 

17354A16-3EC8-46D6-BA7D-8F3CECCA6F60.thumb.jpeg.ffc2fcb78e40798d266a849ebbc6995e.jpeg

Always best to ask the seller for an honest appraisal of the item they are selling. 

Edited by Neverenoughwatches
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