Brass Instrument Specialist
Lacquer today is not the same as the lacquer of yesterday. From the 1920s through current times, various manufacturers tried many different types of synthetic resin based lacquers for finishing brass and wood instruments. This includes cellulose nitrate, acrylics and urethanes. Many older brass instruments were finished with the old nitrocellulose lacquer; modern instruments have a baked-on epoxy lacquer.
I have seen many many older lacquered trumpets, cornets, and flugelhorns, in various conditions. The nitrocellulose lacquer finish has properties which lead to specific results as the instrument ages. It is a known fact that clear nitrocellulose lacquer yellows over time; how long it takes to yellow (or "Amber" as the Gibson company calls it) depends on many factors, including exposure to oxygen, exposure to light, and the types of solvents used when it was applied. It happens to (previously) white drums and guitars, brass instruments, and of course, furniture. Note the references to "yellow" in this following quote from Tauton discussing acrylic vs nitrocellulose lacquer:
Acrylic-modified lacquer is made from a mixture of a nonyellowing cellulose resin (called cellulose acetate butyrate, or CAB) and acrylic. This lacquer possesses the same general properties of nitrocellulose lacquer, except it is absolutely water-white, meaning it will not show as an amber color when applied over light-colored woods. Also, the finish won't turn yellow over time. (From The Tauton Press page on selecting a finish.)
It is most likely that during the manufacturing process, lacquer (nitrocellulose, acrylic, urethane, or epoxy) is applied to brass instruments in a single layer due to the issue of "biting." (When a coat of nitrocellulose lacquer material is applied over another coat of lacquer or similar finishing material, the solvents in the top coat partially dissolve or "bite" into the bottom coat. (definition source:Glossary from Clover Dale Paint, a paint and lacquer provider since 1933.) For wooden instruments, like guitars and drums, multiple coats are applied - with extensive drying and curing time between coats; but brass and nickel are not as porous as wood, and the lacquer may lift and wrinkle with subsequent coats.
The finishing material Nitrocellulose Lacquer is made of nitrocellulose combined
with other resins (to promote flexibility, durability, etc.) dissolved in lacquer thinner solvent.
The lacquer film forms and cures as the solvent evaporates. Lacquer thinner is a volatile, “hot”,
solvent containing a combination of hydrocarbon and chemical solvents - including naphtha, xylene, toluene,
acetone, various ketones, and others. This strong solvent base is lacquer’s best advantage
and primary disadvantage.
For finishing wood instrument and furniture, shellac was used throughout the 19th and into the 20th century. It provides excellent water vapor protection, is fairly simple to repair, and is safe enough that it is approved by the FDA for use on medication. Lacquer came out in the 1920's and has been very popular ever since. Nitrocellulose Lacquer provides "good" water vapor protection and overall durability, although they are prone to cracking and yellowing. (bold exphasis added by me - source: Greg Gaylord, Drum maker.)
The difference between "excellent" and "good" water vapor protection is significant. A finish with only "good" water vapor protection WILL allow metal oxidation to occur. This is why brass and copper will develop a patina beneath nitrocellulose lacquer rather quickly, and why "rose colored" metal doesn't look "rose colored" on an older horn. They were on the day they were lacquered, but within a relatively short period of time (a few days to a few months, depending on the factors listed above) the oxidation patina began. It is interesting to note that examples of early instrument warranties from major manufacturers only guaranteed the lacquered finish for 90 days or at most 1 year. Currently, Yamaha (a contemporary major manufacturer) guarantees their baked epoxy lacquer finish for 3, 5, or 7 years, depending on whether it is a standard, intermediate, or professional model.)
For some collectors, there is a certain appeal to the old aged finish which appears on excellent examples of original condition instruments. The unique appearance comes from a combination of the lacquer yellowing and the underlying metal oxidizing. There is no way to accurately replicate this look when refinishing an instrument. I feel that for players, having the instrument completely rebuilt and refinished is a gain, and as long as this has been done carefully and correctly, I feel it increases the value of an instrument. Instruments which have been poorly reconditioned are devalued.
If the original patina beneath yellowed lacquer finish is desired, the surface of these instruments should be left alone. Things like the valves or slides can still be serviced, and the value of the instrument will increase, since it will now function correctly.
My opinion is that the higher value in the marketplace and greater desirability of instruments in original lacquer w/metal patina showing beneath the lacquer is because it shows that the instrument has never had significant damage or been over-buffed by an underqualified technician attempting to refinish the instrument.
Instruments purchased in this condition provide an excellent starting place for achieving a like-new or better-than-new vintage instrument, in finish and function.
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