Endurance is the oil's ability to maintain the original fast and smooth
valve action over many hours despite playing conditions. This characteristic is very
difficult to develop in an oil without compromising speed because endurance is the
end result of a complex series of interrelated properties and conditions: evaporation
rate, film strength, surface tension, water solubility, and valve cleanliness. The first
property is evaporation rate. In most student and mid-line horns, when a valve oil
evaporates so that less than 40% of the original oil remains on the valves, they will
begin to hesitate in an unpredictable fashion. In more expensive horns with clean
and very tight valves, the slowdown is much sooner and sudden seizing of a valve
is common. In the relative evaporation rate table below, we have listed the percent
of oil remaining on a surface as a function of time at room temperature. The data
does not suggest that a given valve oil will last the number of days shown, but
rather the percentage of oil remaining after a given period of time. Compare the
evaporation rates of the oils with their viscosities, and remember that Endurance is
enjoying fast consistently smooth action for along time - not slow action for a long
time. Some trumpet oil manufacturers include a heavy oil in their formulation to
slow down the apparent evaporation rate, and (hopefully) to make the oil last
longer. Unfortunately, as evaporation occurs, the lighter oil content diminishes
until only the slow heavy oil remains on the valves. All of the testing proved this.
Evaporation Rate Table (Percent Remaining Versus Time)
| Products | Vis.(cSt) | 19 hrs | 48 hrs | 72 hrs | 96 hrs | 120 hrs |
|---|---|---|---|---|---|---|
| WATER | 1.00 | 0% | ||||
| MINERAL SPIRITS | 1.34 | 0% | ||||
| CLARK TERRY | 1.83 | 16% | 7% | 6% | 0% | |
| BENGE | 1.99 | 35% | 13% | 8% | 5% | 4% |
| BLUE JUICE | 1.99 | 44% | 23% | 17% | 12% | 8% |
| PLAYERS | 2.15 | 44% | 20% | 13% | 8% | 4% |
| JUPITER | 2.20 | 33% | 17% | 15% | 13% | 10% |
| ROCHE-THOMAS | 2.31 | 16% | 13% | 13% | 12% | 11% |
| HOLTON | 2.38 | 25% | 7% | 4% | 0% | |
| HYBRID 141-A7 | 3.02 | 92% | 75% | 64% | 55% | 46% |
| PRO-OIL RED | 3.61 | 74% | 44% | 33% | 21% | 11% |
| AL CASS | 3.73 | 75% | 48% | 37% | 26% | 16% |
| PRO-OIL BLUE | 3.80 | 77% | 50% | 37% | 25% | 13% |
| SPACE FILLER I | 5.10 | 100% | 100% | 100% | 100% | 100% |
| SLIDE (t-bones) | 5.12 | 100% | 100% | 100% | 100% | 100% |
| ALISYN | 7.59 | 100% | 100% | 100% | 100% | 100% |
Endurance is very sensitive to the integrity of the oil film on the valve surfaces. As the piston slides down the valve casing it rubs against the oilfilm. This movement tends to rupture the film and allow direct metal/metal contact. In hyper-tight valve assemblies (i.e., Monette and Schilke) oilfilm rupture is potentially more frequent and disastrous. This is a purely mechanical phenomenon which can only be prevented with an oil having a highfilm strength. Achieving a high film strength oil within the optimum viscosity range (2.5 -4.0 cSt) is quite difficult. Although it is not easy to measure this filmstrength directly, it is best understood through demonstration. Firstly, a high film strength will give a smooth, slippery feel when the oil is rubbed rapidly between the fingers. When shaken, an oil with a high film strength will yield bubbles that collapse within 1- 3 seconds. Whereas an oil with poor film strength will tend to entrap air for a much longer time. Oil film rupture can also occur for a different reason: moisture. Water trapped in the valve chamber experiences the shear force of the piston moving rapidly past the walls of the valve casing. This action tends to emulsify the trapped moisture into the oil. This micro emulsion not only has an elevated viscosity, but also displaces the oil from the valve surface. With the oil film thus compromised, the valve and casing easily rub against each other to produce friction, slowed action and wear. Therefore, in addition to the properties discussed above, for an oil to be truly effective it must also resist emulsion formation.
Sticking Valves
How many times have you heard, "My valves were slowing down, so I reoiled with a different oil and suddenly the valves stuck." The tendency is to blame the oil, and although the oil played a part, other causes are more likely for this 'Gunking Up' phenomenon. Every note pushed through the horn is borne in the musician's moist breath with the valve chamber acting as a trap for not only this moisture but the aerosols suspended in it. These aerosols contain enzymes, proteins, and salts. As long as the valve oil rejects this mixture, it will simply pass through the valve chamber. But, as the oil boundary film becomes depleted or compromised, the moisture and its aerosols become attached to the metal. When the musician reapplies oil to the moisture impacted valves (or to valves that had enough time for the spit to dry onto the metal) the oil will actually deposit on top of this layer. As this process is repeated a series of sticky layers and high spots build up until the valves become sluggish or stick completely. There is no oil that can permanently protect against this"spit sandwich" but you can prevent it through effective cleaning and proper oiling.
Corrosion
A lesser know consideration in selecting a valve oil is corrosion. It is absolutely necessary to liberally coat the valve and casing surfaces so that excess oil will transfer to the internal solder joints. In doing so it will protect them against dezincification (red discoloration) and corrosion (blue-green discoloration) which are caused by exposing the naked metal to moisture. Monel valves will similarly be protected against spotting. An oil with low surface tension and a low viscosity will spread quickly and evenly, thereby coating these surfaces without fear of over oiling. It is very difficult to properly coat a valve, the casing and the solder joints with a high viscosity oil. The topic of corrosion will be covered in depth at a later time. Players of rotary valved instruments will want to pay close attention to this article.
How To Select Your Next Bottle Of Piston Valve Oil:
1. A high speed oil is a thinner oil. If you don't recall which oils are heavy, a quick test in a store is to apply a drop or two of each valve oil onto smooth surface (ie. a clean mirror, a sheet of glass or a sheet of metal). Tilt the surface and see how fast the oils run down the sheet; heavy oils move slower and can be eliminated from the selection.
2. The oil should have a slow evaporation rate and be remain slippery. A good evaporation test is to place some of the oil in the palm of your hand and feel how long it feels slippery relative to a different oil. Kerosene based oils are not desirable because they evaporate quickly. The presence of kerosene is apparent from its characteristic odor which will become evident in this test.
3. The film strength is crucial. Hold a group of well capped bottles of high speed oils in your hand, turn them upside down and shake them as a group for 5 seconds. Note how fast the foam breaks; the faster the better. Weed out the ones that have a slow foam break.
4. Water rejection is important. This is a test of how fast the water and oil separate but since it requires sacrificing some oil, a store owner might not want to do it. The test is to add equal amounts of water and the valve oil to a small container (a test tube or even an old bottle), and shake vigorously for 10 seconds. Observe how long it takes for the oil and water to separate almost completely.
Conclusions Of Parts I & II
Speed and Endurance in an oil are two different properties; experience will show that the best oil will not sacrifice one for the other. To quote a long time friend of ours (Art Farmer), "I play very fast, and I have to concentrate on the music. I can't afford to even think about my valves during a performance." To develop an oil for horns built on better technology, one must employ better lubrication technology. Until now, no one has tried to enlighten either the musicians or store owners that there is a science to improving valve oil, and only a few valve oils take advantage of the science. Hopefully the results of our research brought out in this article will dispel the mystique of valve oils, and make oil selection almost bulletproof
Thanks to David Holloway at MusiChem Inc.
Vice President, MusiChem, Inc.
(619) 560-4127