Removing the "Green Cancer"

Discussion in 'Watch Repair' started by f.webster, May 14, 2020.

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  1. f.webster

    f.webster Registered User
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    Dec 18, 2009
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    I have heard it referred to the "Green Cancer". My question is simple: How is it cured?

    I am cleaning the bridges of a project pocket watch and wonder the best way to remove it . Do I polish it off, or scrap it, re-guild it, or just leave it be and never open the watch to show off the movement?

    Remember I am a beginner with watches and DO appreciate everyone's wise counsel. How do you do it? How should I bring beauty back to these bridges?

    20200514_092545.jpg
     
  2. DeweyC

    DeweyC Registered User
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    I just try to stabilize it. Use heptane or IPA on a piece of pegwood and rub off as much as you can. Then into the cleaner. Repeat if needed or until bored.

    Anything else depends on the extent of plate finish lost and the importance of keeping as much intact as possible. Most times the piece will not bear the burden of the cost of proper guilding. But owners are strange creatures.
     
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  3. Jerry Kieffer

    Jerry Kieffer Registered User
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    Typically, If it can not be wiped clean, movement cleaning chemicals will not remove enough of the corrosion to prevent reoccurrence in a short time. In fact, it is unlikely even harsh chemicals will remove all traces required to correct the problem.

    In cases such as this, my personal goal is to remove all traces of corrosion and restore original appearance.

    If you closely inspect a Gilt movement finish, you will often notice that the finish appears to have a very fine bead blast type texture. Thats because thats what it is often used in the manufacturing process to economically blend manufacturing marks into a consistent even finish and appearance. To duplicate this finish, I use a Paasche Airbrush air Eraser attached photo with 320 grit glass bead. This removes all traces of corrosion while restoring original surface texture. I normally use about 20-30 PSI but that is adjusted to match original texture. In addition, after bead work, a small fine brass bristle brush is used to blend invisible where required. Once complete, normal cleaning fluids will blend Gilt color.

    Jerry Kieffer

    fullsizeoutput_5ba.jpeg
     
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  4. f.webster

    f.webster Registered User
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    If this green cancer is a corrosion of the gilt, can it be treated like rust? I have chemicals that treat/remove rust from steel. I have used them on aluminum and cast iron. I wonder is a small amount on a q-tip might help remove the green cancer. Then maybe a light polish?

    Opinions and suggestions...?
     
  5. Chris Radek

    Chris Radek Registered User
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    If it's verdigris on brass, try a gentle acid like vinegar or lemon juice.
     
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  6. gmorse

    gmorse Registered User
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    Hi f.webster,

    Gold is pretty unreactive and resistant to corrosion, that's why it's valuable. The green colour is, as Chris suggests, a corrosion product of the copper in the brass underneath.

    Regards,

    Graham
     
  7. DeweyC

    DeweyC Registered User
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    I forgot to mention my "goto" on chronometer plates and gilt watches. It removes finger stains from chronometer plates (although if etched the prints will still be present) and makes fire gilding look new.

    It is simple soap (AKA Ivory or other true soap), hot water and a brass brush that is as soft as camel hair. I bought 20 of these from Timesavers some time ago out of watchmaker paranoia. I do not know if they are still carried.

    SImply lather up the brush like shaving lather and then scrub the plates. The brown stains will come out as will verdigis. The damage will still be there but it is not so apparent and the plates are bright with no damage to spotting or gilding.

    Rinse in hot water and then I put them through the cleaning machine but you may choose not to.

    I just did a chronometer yesterday. Next time I will take before and after pics. But the secret is the brush. It has GOT to be soft brass.
     
  8. f.webster

    f.webster Registered User
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    So here is what the beginner did. I took the advice I got here and...

    First I put it through the cleaner then I took a pith-stick and with some naphtha I rubbed of as much as I could. Next I took some vinegar and after a short soak I address it again with the pith-stick. Another trip through the cleaner. Then with a soft cloth and some Novus 2 polish, I gave it a pass before final trip through the cleaner. There is still one spot...I'm not calling it cancer... a booger in the serial number. It looks much better.

    I am thankful for those who shared with me.

    20200516_150751.jpg
     
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  9. topspy

    topspy Registered User
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    Here's a junker I did recently, before and after. After derusting the steel bits, I used a nickle silver wire wheel to clean up the bridges, then replated them briefly. I just chucked up the ratchet and crown wheel and gave them a sanded finish. before.JPG before.JPG after.JPG
     
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  10. DeweyC

    DeweyC Registered User
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    Actually, came out much nicer than I would have expected. Congratulations!
     

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