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  1. #1

    Red face Alcohol vs brass....Chemical reaction?

    Not quite sure where to go with this one, not quite case restoration, but not clock repair either, so I put it here.

    I have a problem with an elaborate brass bob that I was cleaning up, it appeared to have some shellac on it, actually it was on the reverse side. Whan I attempted to remove it with some denatured alcohol on a rag and found difficulty in trying to get it out of the nooks and crannies I decided to just soak it in some of the alcohol. After removing it and drying it off I noted that the front side of the bob had turned a sort of white, like some sort of residue was on it. I polished it with some never-dull and it appeared to remove it. However, when it again dried the white returned. Can't figure out what has happended here and am wondering if there is some sort of chemical reaction that has occurred?

    CP
    Last edited by clockpoor; 09-09-2008 at 01:27 PM. Reason: Spelling

  2. #2
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    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    Quote Originally Posted by clockpoor View Post
    Not quite sure where to go with this one, not quite case restoration, but not clock repair either, so I put it here.

    I have a problem with an elaborate brass bob that I was cleaning up, it appeared to have some shellac on it, actually it was on the reverse side. Whan I attempted to remove it with some denatured alcohol on a rag and found difficulty in trying to get it out of the nooks and crannies I decided to just soak it in some of the alcohol. After removing it and drying it off I noted that the front side of the bob had turned a sort of white, like some sort of residue was on it. I polished it with some never-dull and it appeared to remove it. However, when it again dried the white returned. Can't figure out what has happended here and am wondering if there is some sort of chemical reaction that has occurred?

    CP
    I can't imagine any reaction between alcohol and an item that is pure brass. Try putting a piece of pure brass in some alcohol and see whether you get the same reaction. (I'd bet you won't.) In any event you can polish away whatever residue remains on the brass with a wire brush or some more aggressive metal polish, then coat it if you don't want it to tarnish again.

  3. #3

    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    CP, is it possible some of the shellac (or varnish) was left on the brass bob? The alcohol and NEVR-DULL may not have removed everything.

    The white "residue" reminds me of the hazy film that can form over a varnished surface when damaged by moisture (especially when accompanied by heat).


    Michael

  4. #4

    Default Re: Alcohol vs brass....Chemical reaction? (RE: Ansomnia)

    Quote Originally Posted by Ansomnia View Post
    CP, is it possible some of the shellac (or varnish) was left on the brass bob? The alcohol and NEVR-DULL may not have removed everything.

    The white "residue" reminds me of the hazy film that can form over a varnished surface when damaged by moisture (especially when accompanied by heat).


    Michael
    I am not sure. What is surprising to me is that it seems to disappear when I use the never-dull on it, but returns when it dries?

    Here is a photo of what it looks like, photo a little dark but I think shows the extent of the problem. I do not really want to use a brass brush on it, but may resort to it if I have to.


    CP
    Attached Thumbnails Attached Thumbnails Bob.jpg  

  5. #5

    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    It sounds to me like the alcohol partially broke down a coating on the front of the bob. I would try additional soaking in alcohol and scrubbing with a bristle brush, or a more potent solvent like acetone or even paint remover.

    Jeremy

  6. #6

    Default Re: Alcohol vs brass....Chemical reaction? (RE: Jeremy Woodoff)

    Quote Originally Posted by Jeremy Woodoff View Post
    It sounds to me like the alcohol partially broke down a coating on the front of the bob. I would try additional soaking in alcohol and scrubbing with a bristle brush, or a more potent solvent like acetone or even paint remover.

    Jeremy
    I had suspected this might be the case, but was baffled by it's apparent disappearance and reappearance following polishing. Since it was broken down by alcohol I am wondering if it would have been common to treat parts like this with Shellac? I will give it a go with a further soak tomorrow and see what transpires.

    CP

  7. #7

    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    how did it work out?
    Ryan

  8. #8
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    Default Re: Alcohol vs brass....Chemical reaction? (RE: itbme1987)

    CP,
    Do you think the bob is solid brass?

  9. #9

    Default Re: Alcohol vs brass....Chemical reaction? (RE: inbeat)

    Quote Originally Posted by inbeat View Post
    CP,
    Do you think the bob is solid brass?
    That I am not sure of, I assume that it is.

    I have to admit that I have been negligent is getting to this and have not yet attempted further removel of the residue.

    CP

  10. #10

    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    I've never used NEVR-DULL but many metal polishes, after sitting for a while and becoming completely dry will leave such a residue, especially in the nucks and crannys like this bob has. Before applying any more chemical, see if you can simply remove the white residue with a good stiff brushing with a dry bristle brush.

    Bob C.

  11. #11
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    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    Quote Originally Posted by clockpoor View Post
    That I am not sure of, I assume that it is.

    I have to admit that I have been negligent is getting to this and have not yet attempted further removel of the residue.

    CP
    Well, paint remover won't harm metal, as long as you wash it off in a reasonable period of time. If it's a coating, that should remove it.

  12. #12
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    Default Re: Alcohol vs brass....Chemical reaction? (RE: R. Croswell)

    My $.02. I would wager on another type finish being put on it somewhere along the way. The polish has just enough moisture in it to clear it up, then when it dries the "bloom" of color comes out. I'd try the acetone or lacquer thinner and an old tooth brush next. After that acetone/thinner and a 4/0 steel wool. The artificial steel wool, scotch brite, is best as it does not leave particles of steel to rust later. Be careful with the acetone/thinner though. It has a very low flash point and in addition, can make you drunker than a good whiskey if used in a tight place. Outside is good even for a small amount. A chemical mask is better.

    Last shot, seal it with a good brass lacquer after it looks like you want it to be and it will stay that way.

    Lamar Scroogega
    NAWCC member

  13. #13

    Default Re: Alcohol vs brass....Chemical reaction? (RE: scroogega)

    I believe Scroogega is right. Normally, the clouding (whiting of the finish) will disappear with a light coat of lacquer.

  14. #14

    Thumbs up Re: Alcohol vs brass....Chemical reaction? (RE: DBPhelps)

    Finally got around to attempting to clean up this bob today. It is definitely a coating of some type, I'm guessing Shellac since alcohol seems to dissolve it. I soaked the bob in alcohol again this morning and then scrubbed it with a stiff brush and as is evidenced by this photo I have managed to get about 90% of the coating off. I will go ahead and soak it some more and that should remove it all.

    CP
    Attached Thumbnails Attached Thumbnails bob.5.jpg  

  15. #15

    Default Re: Alcohol vs brass....Chemical reaction? (RE: clockpoor)

    CP, always use a brush with bristles made of material that is much softer than the object you are cleaning. I think nylon or natural bristle would be safest. Let the solvent soften whatever you are trying to remove. You want the brush to scratch the coating, not the brass.

    Any stiff material will abrade whatever you are cleaning to some degree.

    The charm of an antique casting is in how much of its original details it retains. The more you abrade the casting, the more details you will lose. Similarly, the thicker the varnish or plating you apply, the more the new layers will detract from crisp detailing, even if the coating material is transparent.


    Michael

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