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Workshop/
| Addressing Monel valve discoloration During the past five years there has been an increase in discoloration on the Monel valve, the quality standard piston of the instrument manufacturing world. The Monel valve is 80% nickel and 20% copper with trace amounts of iron. Since there is no common alloy, each manufacturer experiences different discoloration. Yamaha turns black and gold; Holton, brown and gold; and Jupiter turns green, brown and pink.
The National Association of Professional Band Instrument Repair Technicians (NAPBIRT) held a forum on the Monel discoloration phenomenon at their 1999 convention. There were many opinions as to why this problem has suddenly appeared after so many years without it. Everything from the increased use of recycled metals, environmental changes and fast food diets affecting saliva was explored.
There were a few areas of general agreement regarding the discoloration. This is the result of the natural breakdown of the metals but there have been positive results regarding the use of valve oils. Generally, it is better to stick with petroleum and kerosene based oils. There is no definitive evidence that synthetic lubricants impact negatively on the problem. Frank Jackson, Marshall Music’s manager of band instrument repair, suggests sticking with one or the other. Mixing synthetic lubricants and natural petroleum products tends to increase the likelihood of discoloration.
Changes in the manufacturing process mandated by the EPA may have some negative impact. The use of different regulated solders and fluxes has changed the temperatures used in braising valves and casings. Changes in chemicals used in cleaning and processing the materials could be affecting the stability of the brass in the casings and the Monel piston and increased use of recycled metals may produce more contaminants in the metals.
The instrument manufacturers have been very sensitive to the discoloration issue. They are instituting more rigorous cleaning methods in the manufacturing process, more exacting tolerances – up .001” – in the manufacture of the valve casings and pistons, experimenting with the use of silver plated pistons and have recommended procedures in the aftermarket cleaning of the instrument to reduce the possibility of discoloration.
What can your students do to decrease the chances of valve discoloration? Keep the instrument clean using a mild liquid dish detergent and cold water and do not mix the lubricants. Stay with petroleum or kerosene based lubricants, or stay with synthetic based oils. Do not interchange the two. That probably means students should not borrow their classmate’s oil.
This discoloration will not affect the playing or tone qualities of the instrument. With some awareness and attention to the proper care of the valves, hopefully, this problem can be minimized |
