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Vintage Trumpets / Cornets Discuss is that red rot? in the Equipment forums; Beautiful Vintage Conn 12A Coprion Professional Cornet - eBay (item 270278217415 end time Sep-27-08 15:29:51 PDT) Photo #7 shows some ...
  1. #1
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    is that red rot?

    Beautiful Vintage Conn 12A Coprion Professional Cornet - eBay (item 270278217415 end time Sep-27-08 15:29:51 PDT)

    Photo #7 shows some suspicious areas on the bell bow of that Conn 12A.

    I asked the seller if there is any red rot corrosion there on the bell bow or anywhere else on the cornet, and he said no.

    But that area on the bell bow does not just look discolored.
    It actually looks pitted.
    But it is impossible to know if the pitting is from the inside (red rot) or from the outside (the Holton Super Collegiate I once owned had *extremely* minor exterior pitting in the copper in that same area of the bell bow).

    Any expert opinions here about whether that is red rot?
    I admit that the bell bow would be an unusual place for red rot to happen.

    - Morris

  2. #2
    Utimate User Dale Proctor's Avatar
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    Re: is that red rot?

    I don't think that copper can "red rot". Brass is an alloy of copper and zinc, and when the zinc is eaten by acids, all that's left is the copper, which leaves the red color in the brass. It's really the zinc that rots in brass, not the copper, so copper won't "red rot". What you're seeing is some pretty good corrosion, though.
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    Re: is that red rot?

    Quote Originally Posted by Dale Proctor View Post
    I don't think that copper can "red rot". Brass is an alloy of copper and zinc, and when the zinc is eaten by acids, all that's left is the copper, which leaves the red color in the brass. It's really the zinc that rots in brass, not the copper, so copper won't "red rot". What you're seeing is some pretty good corrosion, though.
    Interesting point, and I think you must be right.

    But what is it then that causes the exterior pitting that is seen in the copper bell bow of that Conn 12A and the Holton Super Collegiate I used to own?

    I used to think that aluminum could last forever, too, but then I saw that my neighbor's gutter downspouts had large holes in them from the equivalent of rusting out, although aluminum doesn't rust.

    - Morris

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    Re: is that red rot?

    Hi,

    I have an unlacquered coprion bell on an Olds Ambassador and it gets the same patchy dark look after awhile out of the case. Nothing that a little Nev r Dull can't fix.

    Cheers,

    Brian
    "Swift Current - where we're neither swift nor current"

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    Utimate User Dale Proctor's Avatar
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    Re: is that red rot?

    Quote Originally Posted by screamingmorris View Post
    ...But what is it then that causes the exterior pitting that is seen in the copper bell bow of that Conn 12A and the Holton Super Collegiate I used to own?...
    Oxidation, corrosion, rust, or whatever you want to call it. It's basically the surface of the metal corroding away, so eventually, it can pit and make a hole. Depends on the metal and the environment it's subjected to.
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    Re: is that red rot?

    Quote Originally Posted by Dale Proctor View Post
    Oxidation, corrosion, rust, or whatever you want to call it. It's basically the surface of the metal corroding away, so eventually, it can pit and make a hole. Depends on the metal and the environment it's subjected to.
    Exactly. Hold up a 1940s penny beside a 2008 penny, and you'll see a similar color difference. The patches on the bell flare and the crook must have lost their lacquer quite a while ago. As soon as the air hit the raw copper, it did what it does to pennies: turns them dull orange, then brown, then darker brown, and, if you wait long enough and don't disturb the corrosion, green like the Statue of Liberty. I would think the blotches could be cleaned with any good metal polish, like Flitz, to restore the bright orange color and lustre seen on the rest of the bell and then either touched up with lacquer or sealed with a good coat of wax. But I would not be concerned that any of those patches represent anything more than an aesthetic problem. Copper is actually one of the most durable metals; that's why gutters and downspouts (and an entire roof, if you could afford it) are made of it. It would take a long, long time for any deterioration to actually pit the metal significantly.

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    Re: is that red rot?

    I have a coprion belled Conn trumpet. It is now raw brass. The lacquer was mostly gone. The curve of the bell rode against a relatively unpadded part of the case and rubbed the finish there off first and the copper corroded. It had the same color as the picture in the auction. I used Mothers Billet Polish and it came back to nice shiny copper. I can not tell any difference in the color or finish between the corroded area and the rest of the horn today. I think that the diffent metals used in coprion belled horns can set up galvanic cell corrosion and the can look pretty bad but usually polishes up nicely.
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    Re: is that red rot?

    Just to remind everyone what I was talking about in my original post that started this thread.

    I didn't mind the color of the tarnished copper on the bell bow of that eBay Conn 12A.
    I was concerned about the tiny *holes* that I see in the surface of the copper.

    - Morris

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    Re: is that red rot?

    Either your eyesight is a whole lot better than mine, or you have a more finely focused monitor screen. I can find no evidence of any pitting on that picture of a bell bow.


    In addition to the above, I have yet to see red rot in an area of a horn that has an adequate flow of air and no joint between two pieces of tubing, where moisture can accumilate without being flushed free by an undisturbed flow of air. Leadpipes are notorious for red rot because of the large volume of spitum and condensation that are constantly flowing through that segment of plumbing. This is exacerbated by the all too common lack of cleaning by the 'musician'. If no other means are readily available, such as soaking and running a brush through the pipes it would be wise to pull the tuning slide and run a stream of water through the leadpipe, if not the entire horn on an every use basis. In my opinion, these hunks of brass are far to pricey to just let them rot away from lack of care.


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