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  1. #1
    Registered user. Robert Ling's Avatar
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    Default What was used to black out the glasses on early to mid 1800's Banjo's, etc.

    I recenty aquired a Howard & Davis Banjo with original untouched glasses.
    Whatever was used to black out the glass has thinned and lifted to a translucent state.
    It's an aged effect that would probably be impossible to reproduce.
    I'm not wanting to do anything to these glasses, as I like them as they are, but I'm wondering what might have been used back in the 1840's to blacken them ?

  2. #2

    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Robert Ling)

    Bob,

    What has/is happening is the adhesive bond between the glass and paint is failing, it's only going to get worse. I believe they used oil based black paint. I use alkyd enamel for restorations. You have to make sure the glass is absolutely clean before applying paint. I personally like mine looking new. Others will disagree but these were not individual works of art, they were production pieces.

    Regards,
    Jeff

  3. #3
    Registered user. RJSoftware's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: the 3rd dwarve)

    There is a process used to re-adhere and flatten paint that is seperating like yours.

    I forget the name exactly now, I think Tom_T and his extreme restoration has the info.

    Anyway, the process goes like so: Take the glass and fit it into a sealable container like tupperware. Face it glass side down.

    Put a small glass of paint thinner or simular inside the case, but so it is not touching.

    Then allow some time for the fumes to fill the case and as it does it softens the paint and restores it back to flat on the glass. The softening effect allong with gravity will force the paint back onto the glass.

    I think it even gets rid of air bubbles. Not sure.

    Anyway, somebody will tell you the name or maybe good search. I think the jury is still out on this, but also think I read that museums practice this. They may know the finer points. One thing would be the duration. Maybe too long and you got a goopy mess. Or not...!

    RJ
    The bitter the challenge, the juicy the conquest.
    Conquest -> https://www.youtube.com/watch?v=NGaVUApDVuY

  4. #4
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: RJSoftware)

    The backing varnish on gilt glass would most likely have been a varnish with lamp black. This subject was touched on some months ago, with regards to backing for gilt glass. Eising glass of something like that was used. I have a download of a booklet that explains it all (published 1905). I'll rout it out. (Steven T has a copy and might be able to find it quicker.)

  5. #5
    Registered user. Robert Ling's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: laprade)

    Thank's for all the info guys and please keep it coming.

  6. #6

    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Robert Ling)

    My impression over the years has been that several treatments were used on the backs of Attleboro style banjo timepiece tablets, including paint, depending on the maker and also the whim of the maker at any particular time. I have been told that asphaltum was used, as well as paint, and I have added a couple of pictures here of a Wallace Goodwin banjo from my collection. I believe the backing on the glass to be asphaltum, and not paint or varnish. One indication of this is the translucency that it has achieved over the years, sort of like what you describe on your tablets. The material doesn't as much chip or peel off, as it does evaporate, or maybe oxidize. When looking through such a tablet into a strong light, the color seems to be almost brownish black, maybe with a hint of orange, not the dead black that paint imparts. I don't know if anyone has ever really done a proper analysis of these surfaces, and according to Lee Davis, very little was written down in the shop records of these companies, probably because what they were doing was considered so common at the time.

    I certainly wouldn't do anything to modify or "improve" your banjo tablets- they are over 160 years old, and original, unlike so many of them that have been overpainted. They have aged gracefully, and not been subjected to plastic surgery to make them look younger, and you are lucky to have found them in this condition. Once "improved", there is no reversing the process. Many tablets have been, for all intents and purposes, seriously damaged by well intended repairs.
    Attached Thumbnails Attached Thumbnails goodwin.jpg   goodwintablet.jpg   goodwintabletfront.jpg  

  7. #7
    Registered user. Robert Ling's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Peter A. Nunes)

    Peter,
    My glasses look simular when the door is open, with a bit more of the black intact. When the door is closed the losses are not apparent.

    I have a dated 1873 E. Howard #5 with original glasses, and the black in the glasses has taken on a kind of smoke gray hue. It is another interesting aged effect.
    There is a John Polsey timepiece on pg. 165 of Paul Foleys book that the glasses grayed in this way.

  8. #8

    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Robert Ling)

    Quote Originally Posted by Robert L View Post
    Peter,
    My glasses look simular when the door is open, with a bit more of the black intact. When the door is closed the losses are not apparent.

    I have a dated 1873 E. Howard #5 with original glasses, and the black in the glasses has taken on a kind of smoke gray hue. It is another interesting aged effect.
    There is a John Polsey timepiece on pg. 165 of Paul Foleys book that the glasses grayed in this way.
    I think, but am not sure, that what you are seeing is a difference in the way light affects the tablet in areas where the paint or whatever it is has lifted.

  9. #9

    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Peter A. Nunes)

    These visual effects that we have been talking about take decades to achieve. The slight translucency, the graying you mentioned, etc., are to me beautiful patina that is not reproducable. Only exposure to air, light, heat, cold, etc., can bring about these changes. Certainly they add to the appeal and maybe the value of a timepiece.

    As a collector, these are among the things I look for. I think there are probably times, when there is nearly complete loss of the blacking, that re-coating may be justified, but I would think long and hard about it, and if it was a good, valuable example of its type, I would have it done professionally. I have seen some horrific examples of home-made restoration work (I did some fine damage myself back in the early 1970's).

  10. #10
    Registered user. Robert Ling's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Peter A. Nunes)

    Another thing I've noticed with my H&D is it has a balanced patina look to it, with the case finish, dial, and glasses, all having aged together.

    When you think of what has to take place in order for a Banjo timepiece's glasses to survive for 160 years it's kind of daunting.

  11. #11

    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Robert Ling)

    Everyone looks at things through their own eyes but I couldnít agree with you guys less.
    These tablets are not Rembrandts or DaVincis. They were production pieces. Itís not like they all have deteriorating tablets. Many have survived beautifully.

    Itís been my experience with Howards that buyers find original pieces the most desirable. Barring 100% originality well restored pieces sell for higher money than unrestored pieces.

    I think leaving a degrading tablet with sever paint loss in the clock makes it look shabby. The tablets you are depicting are simple designs and with a little effort can be brought back to factory condition. Once restored they no longer draw the viewerís eye to them but allow the overall beauty of the clock to become apparent. I can understand if you do not want to attempt the restoration yourself or if the value of the clock does not justify have the restoration done but any Howard should be valuable enough to justify this small expense.

    I have had this discussion before but would like to hear the memberís thoughts on it
    again.

    I have attached pictures of a #26 before and after.

    Regards,

    Jeff
    Attached Thumbnails Attached Thumbnails #26 1.jpg   #26 2.jpg   #26 3.jpg   #26 4.jpg  

  12. #12
    Registered user. Robert Ling's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: the 3rd dwarve)

    I guess the desire to restore aged glasses or not depends on several things with an individuals tast being a main one.
    And I agree that losses to a dial or glasses that are very noticable can detract from a clocks good looks.
    To me it's a clock by clock determination, made by the sum of it's parts and the type of clock in question.

    Jeff, What is the pull chain on the side of your #26 for ?

  13. #13
    Registered user. RJSoftware's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: Robert Ling)

    Ah now I remember, the process to get the paint to re-liquify and adhere to the surface of the glass is called the Pettenkoffer process.

    And it uses acetone although it was suggested that laquor thinner be tried first because it's less agressive.

    Since you put the glass in a sealed container like a tupperware container or simular air tight, with small bottle of acetone or laquor thinner, I suppose also you have to make sure condensation does not drip from the lid down.

    If the process works as reported then you have your restoration allong with all originality.

    RJ
    The bitter the challenge, the juicy the conquest.
    Conquest -> https://www.youtube.com/watch?v=NGaVUApDVuY

  14. #14

    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: RJSoftware)

    Hi Bob,

    The #26 was an early, mechanical, watchman's clock made before the advent of electricity. The pull chain moves a lever that pulls rods connected to the lower arm that pushes in a pin on the lower dial so management would know that the watchman was there at a given time the night before. Few of these have survived with the lower recording movement intact.

    Regards,

    Jeff
    Attached Thumbnails Attached Thumbnails #26 LOWER DIAL.jpg   #26 LOWER MOVEMENT 2.jpg  

  15. #15
    Registered user. Robert Ling's Avatar
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    Default Re: What was used to black out the glasses on early to mid 1800's Banjo's, etc. (By: the 3rd dwarve)

    Jeff,
    So when the watchman pulled the chain a pin would mark the time on the lower dial. Was any paper involved giving a punched out receipt. Or was the the viewing of the lower dial the only recording ?
    Also was there any locks on the case to prevent tampering ?
    -> posts merged by system <-
    Quote Originally Posted by RJSoftware View Post
    Ah now I remember, the process to get the paint to re-liquify and adhere to the surface of the glass is called the Pettenkoffer process.

    And it uses acetone although it was suggested that laquor thinner be tried first because it's less agressive.

    Since you put the glass in a sealed container like a tupperware container or simular air tight, with small bottle of acetone or laquor thinner, I suppose also you have to make sure condensation does not drip from the lid down.

    If the process works as reported then you have your restoration allong with all originality.

    RJ
    Thanks RJ
    I remember reading of this process too. I think I would do a test run first and watch it closely.
    Last edited by Robert Ling; 04-02-2011 at 04:13 AM.

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