Brass Chemical Attack?

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  1. #1
    kokomodo's Avatar
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    Mar 2007
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    Question Brass Chemical Attack?

    Every once in a while I clean the end of my tenor neck (the end that fits into the body tube) with my shirt, a rag, whatever is handy to facilitate a smoother fit into the body. I suppose it cleans off "gunk". Last week I picked up a silk cloth that I use to pull through the body to remove moisture from the horn. The cloth was dry at the time. I cleaned the neck and inserted it into the body. After I finished playing I tried to remove the neck from the horn. No way. The neck was almost completely stuck. It would turn just a bit, but would not pull out of the horn. I tried heating the body/cooling the neck, slowly working the neck back and forth for quite a while. Finally I got the neck out and found a greenish white powder all over the brass. Clearly, some sort of chemical reaction had happened, but what? I cleaned the body and neck with a clean cotton cloth and reinserted the neck. Smooth and silky...great fit and no binding. So, techie types...what happened? Was it the silk rag? The residue of old saliva on the silk rag? Acid in the saliva? What would cause brass to react that way?

    Inquiring minds want to know.


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  3. #2
    Distinguished Technician & SOTW Columnist
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    Feb 2003
    Auckland, New Zealand
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    Default Re: Brass Chemical Attack?

    Who knows what was in the silk rag!
    Who knows what a player blows down his sax.

    Saliva contains minerals, which dry to a white powder. This collects in the neck of some saxes, depending on the player.

    The player blows some carbon dioxide into the sax. This dissolves in the ever-present moisture in the breath to make carbonic acid. Carbonic acid plus brass (copper and zinc), I suppose will eventually make some copper carbonate (green?) and zinc carbonate (white?).


    This is not normally a problem unless you leave that moisture sitting there, to dry out.
    Corrosion between surface of tenons and sockets is far worse if the instrument is left assembled for long periods, with moisture inside.
    It is also far worse if that tenon fit (when cleaned of corrosion) has at least some parts that are a loose fit, where moisture can gather.

    I suggest you clean both the tenon and socket with a reputable polish formulated specifically for brass (not a whole list of other metals also!) Make sure you rub off all traces of polish with a clean cloth before you next assemble the sax. Most polishes have a residual tarnish preventer. The neck tenon, when polished, should slip in firmly but very smoothly. If it does not, then get a technician with the required specialised tools to adjust it.
    Contentment is not the fulfilment of what you want, but the realisation of how much you already have.

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