Damaged Lacquer
With a lacquered horn it is inevitable that the finish will eventually get damaged. This can occur when the horn is scratched, if the lacquer gets chipped, or if the horn gets dented. It can also eventually occur simply through exposure to sunlight, or decomposition of the lacquer through age; even a well-cared for instrument will eventually have its finish compromised through normal wear and tear. This is why historically when companies have offered a guarantee on their horns that guarantee has not included the lacquer finish.
Once the lacquer gets even the smallest hole, a process will begin that can only be stopped by removing the lacquer from the instrument. As soon as there is a hole in the lacquer the outside environment will begin to attack and corrode the brass. The biggest enemy to the horn at this point is the perspiration (sweat) from the player’s hands. This sweat will contain small amounts of electrolytes (salts) and acids, which will find their way into the tiniest chink in the lacquer coating. Once inside they will become trapped, and that is when the mischief can begin. Those salts and acids, together with a little moisture will get to work on the brass. Brass is an alloy composed of two main metals: copper and zinc. When all of these ingredients are combined (copper, zinc, salt, acid, and moisture) the result is that a tiny electric charge is generated. Because the lacquer traps all of these ingredients together and holds them there permanently, the corrosion of the brass is greatly accelerated wherever the lacquer is damaged. The result is that after a few years deep pits or etch marks will be permanently bored into the surface of the instrument. There is one way to prevent this, or at least minimize these effects: all lacquered horns should be waxed often with a compatible clear coat wax polish. If this is done before any damage occurs and continued for the entire life of the instrument, then any cracks or scratches or tiny holes can be kept sealed, preventing the player’s sweat from ever getting under the lacquer in the first place.
Note: Companies do not guarantee the clear plastic finish on new instruments. The plastic coating is only there to protect the horn while it is in storage before it is purchased, but as soon as the horn is bought there is generally no warrantee or guarantee of any kind. This is because in most cases lacquer only lasts for a few years of use before it begins to degrade.
Here are a few examples of Manufacturer Guarantees for the lacquer on their horns:
C. G. Conn:
With a lacquered horn it is inevitable that the finish will eventually get damaged. This can occur when the horn is scratched, if the lacquer gets chipped, or if the horn gets dented. It can also eventually occur simply through exposure to sunlight, or decomposition of the lacquer through age; even a well-cared for instrument will eventually have its finish compromised through normal wear and tear. This is why historically when companies have offered a guarantee on their horns that guarantee has not included the lacquer finish.
Once the lacquer gets even the smallest hole, a process will begin that can only be stopped by removing the lacquer from the instrument. As soon as there is a hole in the lacquer the outside environment will begin to attack and corrode the brass. The biggest enemy to the horn at this point is the perspiration (sweat) from the player’s hands. This sweat will contain small amounts of electrolytes (salts) and acids, which will find their way into the tiniest chink in the lacquer coating. Once inside they will become trapped, and that is when the mischief can begin. Those salts and acids, together with a little moisture will get to work on the brass. Brass is an alloy composed of two main metals: copper and zinc. When all of these ingredients are combined (copper, zinc, salt, acid, and moisture) the result is that a tiny electric charge is generated. Because the lacquer traps all of these ingredients together and holds them there permanently, the corrosion of the brass is greatly accelerated wherever the lacquer is damaged. The result is that after a few years deep pits or etch marks will be permanently bored into the surface of the instrument. There is one way to prevent this, or at least minimize these effects: all lacquered horns should be waxed often with a compatible clear coat wax polish. If this is done before any damage occurs and continued for the entire life of the instrument, then any cracks or scratches or tiny holes can be kept sealed, preventing the player’s sweat from ever getting under the lacquer in the first place.
Note: Companies do not guarantee the clear plastic finish on new instruments. The plastic coating is only there to protect the horn while it is in storage before it is purchased, but as soon as the horn is bought there is generally no warrantee or guarantee of any kind. This is because in most cases lacquer only lasts for a few years of use before it begins to degrade.
Here are a few examples of Manufacturer Guarantees for the lacquer on their horns:
C. G. Conn:
Vincent Bach:
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F. E. Olds:
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Red Rot/Dezincification
In extreme cases the corrosion of a lacquered or silver plated instrument can develop into a condition known to instrumentalists as “Red Rot”. This occurs when concentrated spots of corrosion appear on the horn, and through a process called “dezincification” bright pinkish-red spots appear to bloom beneath the lacquer or silver plate. This is usually accompanied by a raised spot in the center, either white or greenish in color. This process is caused because under the right conditions, the zinc in the brass will oxidise and leach out of the metal, leaving behind pure copper. The raised white bump in the middle is zinc oxide, and the bright pink blemish on the horn is the copper that is left behind. When this occurs the structural integrity of the metal is compromised. The pure copper metal that remains is full of holes where the zinc used to be, and it is left in a weakened state. Horns with an advanced case of this will develop holes, and can crack and even crumble away. If this is caught early then there is only one cure: the horn should have the lacquer removed immediately so that the salts causing the concentrated corrosion can be removed. The horn should then be washed in a very hot bath of concentrated soapy solution, so that the alkali (basic) nature of the soap can neutralize any acids that have built up in the affected areas. The horn can then be left in a raw brass finish, or, if desired, resprayed with a fresh coat of lacquer.
Why does this happen?
Red rot occurs because all metals do not oxidize at the same rate. The speed with which a metal will corrode is known as its “nobility”. A metal that is highly noble, such as gold or titanium, will corrode very slowly. A metal with low nobility, such as zinc or steel will corrode more quickly. A metal with very low nobility will also corrode preferentially to another metal if they are in contact with each other. Zinc is one of the least noble of all metals; this is why you can attach a zinc bar to a steel bridge or evaporative cooler to prevent the steel from corroding. Because the zinc has such low nobility, it will corrode first, and until the zinc is completely corroded away the steel will not rust. The same is true if you attach a zinc rod to a copper plate and immerse them in seawater; the copper will not begin to corrode until the zinc has completely rotted away.
Under normal conditions, brass is actually a fairly stable metal, with a relatively high nobility. The copper and zinc are very tightly interwoven, so they both corrode together at a slow rate. Red rot can only occur under special environmental conditions, when, through a process similar to electrolysis, the zinc and copper are ripped apart. When this occurs the zinc, due to its very low nobility, will immediately oxidize, and only pure copper will be left behind.
In extreme cases the corrosion of a lacquered or silver plated instrument can develop into a condition known to instrumentalists as “Red Rot”. This occurs when concentrated spots of corrosion appear on the horn, and through a process called “dezincification” bright pinkish-red spots appear to bloom beneath the lacquer or silver plate. This is usually accompanied by a raised spot in the center, either white or greenish in color. This process is caused because under the right conditions, the zinc in the brass will oxidise and leach out of the metal, leaving behind pure copper. The raised white bump in the middle is zinc oxide, and the bright pink blemish on the horn is the copper that is left behind. When this occurs the structural integrity of the metal is compromised. The pure copper metal that remains is full of holes where the zinc used to be, and it is left in a weakened state. Horns with an advanced case of this will develop holes, and can crack and even crumble away. If this is caught early then there is only one cure: the horn should have the lacquer removed immediately so that the salts causing the concentrated corrosion can be removed. The horn should then be washed in a very hot bath of concentrated soapy solution, so that the alkali (basic) nature of the soap can neutralize any acids that have built up in the affected areas. The horn can then be left in a raw brass finish, or, if desired, resprayed with a fresh coat of lacquer.
Why does this happen?
Red rot occurs because all metals do not oxidize at the same rate. The speed with which a metal will corrode is known as its “nobility”. A metal that is highly noble, such as gold or titanium, will corrode very slowly. A metal with low nobility, such as zinc or steel will corrode more quickly. A metal with very low nobility will also corrode preferentially to another metal if they are in contact with each other. Zinc is one of the least noble of all metals; this is why you can attach a zinc bar to a steel bridge or evaporative cooler to prevent the steel from corroding. Because the zinc has such low nobility, it will corrode first, and until the zinc is completely corroded away the steel will not rust. The same is true if you attach a zinc rod to a copper plate and immerse them in seawater; the copper will not begin to corrode until the zinc has completely rotted away.
Under normal conditions, brass is actually a fairly stable metal, with a relatively high nobility. The copper and zinc are very tightly interwoven, so they both corrode together at a slow rate. Red rot can only occur under special environmental conditions, when, through a process similar to electrolysis, the zinc and copper are ripped apart. When this occurs the zinc, due to its very low nobility, will immediately oxidize, and only pure copper will be left behind.