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  1. #1
    Registered User new2clocks's Avatar
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    Default How do you polish onyx?

    Hello all,

    I just acquired an Ansonia crystal regulator, a Gonfalon model, made of Brazilian green onyx.

    I also have a Gonfalon in white onyx.

    Whereas the white onyx clock is smooth as a baby's behind, the green onyx is somewhat rough. I would like to polish the green onyx and would appreciate suugestions on the best way to do so.

    Thanks in advance and regards.

  2. #2
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    Irish, but live in Laprade, 16390, France, (70 miles east of Bordeaux)
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    Default Re: How do you polish onyx? (RE: new2clocks)

    Polishing of stone is done two ways: 1/ very slow (weeks) in a revolving drum, for semi precious etc, 2/ using buffing machines as in the case of monumental masonry, buildings, grave stones etc.

    If there is a stone yard near you, go and ask them for advice.

    Pumice is involved and quite possibly in the case of fine stone, jeweller's rouge, which is used to polish glass bevels after grinding.

  3. #3
    Registered User new2clocks's Avatar
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    Default Re: How do you polish onyx? (RE: laprade)

    Quote Originally Posted by laprade View Post
    Polishing of stone is done two ways: 1/ very slow (weeks) in a revolving drum, for semi precious etc, 2/ using buffing machines as in the case of monumental masonry, buildings, grave stones etc.

    If there is a stone yard near you, go and ask them for advice.

    Pumice is involved and quite possibly in the case of fine stone, jeweller's rouge, which is used to polish glass bevels after grinding.
    Thank you, laprade.

    Is there a method that can be done by hand or with small tools?

    Regards.

  4. #4

    Default Re: How do you polish onyx? (RE: laprade)

    For Onyx clock cases, I personally have been very successful in restoring a near-mirror smoothness to the material using the same abrasive finishing papers that automobile paint and body workers use by hand.

    All metal interior and external parts must be removed because of the large amounts of water needed during the "wet sanding" process. For very rough areas, no coarser than 320 "wet-or-dry" paper is used with plenty of water, followed by 400 grit, 600 grit etc. Cut the supplied abrasive paper into fourths.

    Sanitation is critical. Any residual coarser Onyx or Marble removed must not contaminate the finer abrasives, else deep scratches will ensue.

    For flat areas, block sanding helps but for curves, the paper has to be wrapped around the hand. Again; always wet sanded ! The work is messy and wet; best done out-of-doors, the residual removed Onyx or Marble "dust" has to be washed away, else it will contaminate the abrasives leaving scratches.

    The final finish is grit 2000 or as Laprade suggests, a very fine pumice. (if you can find the finest grit grain size. The important thing about abrasives as others have advised is consistency of the grain or grit size.

    Finally, protect the surface with a good hard wax. Some experts advise buffing the hard wax coatings with a high-speed rotary brush the heat from the fast moving brush smooths the wax to a bright luster.

    The wax finish is important to protect the Onyx from any acidic fluids or moisture that can become acidic.
    Last edited by Eckmill; 06-19-2010 at 09:59 AM. Reason: emphasis on elbow grease
    H.J. (Les) Lesovsky, Alhambra California

  5. #5
    Registered User new2clocks's Avatar
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    Default Re: How do you polish onyx? (RE: Eckmill)

    Thank you, Les.

    Regards.

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