Chemistry in Cleaning Instruments

Instrument cleaning products generally rely on similar properties of the solutions used. For instance, the type of water used (tap, distilled, de-ionized, etc.), the temperature and pH of the solution, buffering agents, catalysts or inhibitors, etc. are all heavily considered when a chemist is creating the cleaning product. To fully clean most instruments, it is best to place the instrument in a tank full of the solution and shake or stir the water, as long as it does not damage the instrument. Generally, these solutions function best at 100-140º F, and are basic with a pH of about 9 in order for the chemicals to stay stable and dissolve protein and fatty residues (since a few chemicals in cleaning products are less stable at lower temperatures).

As far as brass instruments go, cleaning is usually as simple as submerging the instrument and running a snake brush through it, with maybe some soap. However, the maintenance of a hunk of metal that moves and requires precise tuning can be more laborious.  When you go to purchase a brass instrument, depending where you go, they’ll often offer to sell you a starter’s pack at a great deal (which is usually a rip off). But in those kits there is one thing that is definitely essential and you would have to buy anyhow. This is valve oil, an essential lubricant for your instrument. There are many types of valve oil, some specialized for rotary valves (like french horn, some tubas, bass trombones, and some strange trumpets), and others for the standard piston valve. In addition to this, a slide grease is also desirable for you slides (tubes of metal that you can pull out and push in varying amounts to affect tuning).  Both these substances have a similar basic goal, allow smooth movement of a part on the horn, and create a bit of a seal that ensures there are no air leaks.  The difference, is the valve oil is designed for the valves to move quickly, swiftly, and quietly, whereas the slide grease is to cause the slide to stay stuck in the same position, yet still be adjustable later.  You’ll notice the physical difference between these substances is valve oil is an oil in a bottle, and slide grease is a lard-like material in what looks like a chapstick (be warned, do not make that mistake!).  These substances are both lubricants, and you should noticed that they are both best described when equated to common fats (oil and lard), and this is because a lubricantis a fat or a lipid.

It is comprised of saturated carbon chains (see above), and has the useful quality of being adhesive to both surfaces (so that it is not rubbed of the contact surface), but still provides separation between the two surfaces. This separation allows for smooth motion.

Now, you should be able to tell that some oils are thicker than others, and you should especially be able to tell that slide grease is much thicker than valve oil. As stated on the same site where these wonderful images come from, oils tend to have carbon chains of 15-20 carbons, whereas greases have carbon chains from 20-25 carbons. By adding more carbons, you make it so that the chains get ‘tangled’ together more, causing the material to move more slowly. Imagine taking a bunch of short 1/2″ snippets of string laid out, and rolling them around with the heel of you palm. Nothing would really happen. But if you did this with a bunch of 6″ strips, they’ll start to tangle around each other, inhibiting further motion.

As far as lubricating instruments goes, there’s no need to work outside of room temperature (or roughly near that), however since we are on the topic of lubricants, there is one other thing that needs mention. Now we know that as the energy of the system (a lubricant) increases, such as by temperature increase, the molecules begin to move around more and overcome their Inter Molecular Forces (IMF). If we look at any standard saturated carbon chain,  you’ll see that being perfectly symmetrical and only containing C-C and H-C bonds, the only IMF present would be LDF.  So, if as the temperature increases, the energy increases to a point where the lubricant vaporizes by overcoming IMF, the simplest way to counteract that and allow our lubricant to work at higher temperatures is to use a longer carbon chain which would result in a higher IMF.  Therefore, thicker lubricants are used in the presence of heat, such as in the engines of the machines that shape brass or in the equipment that handles the melted metal alloys at extremely high temperatures.

Although brass elements are generally cleaned with trichloroethylene and perchloroethylene, violins are usually cleaned with phenolic resin solutions, resorcin/formaldehyde solutions, or saligenin/formaldehyde solutions. The resorcin/formaldehyde solution is mainly used to give the wood an “outside shell” and keep the wood strong so it does not erode. The saligenin/formaldehyde is used to hydrolyze with the debris on the instrument so it may be removed after being rinsed. The phenolic resin solution ( (HOC6H4CH2)2O + H2O ) is the most common one since its the most active in the cleaning process. The solution does not only also give the instrument is sturdy shell, but its alkaline properties enable it to also remove debris the most effectively. Further, this solution generally decreases the dampening of the sound produced. After the violin is soaked in these solutions, it is rinsed off and dried so it may be used like it is brand new once again.

While the tuning of a piano is a more complex process than that of any mobile string instrument, the cleaning of piano strings is that of very intricately detailed work.  It is much more necessary than cleaning of, say, violin strings, as the metal materials that make piano strings and their coiling are much more prone to rust and environmental decay.  The copper strings in the lower register of the piano, specifically, can be ruined over time without proper cleaning in areas with a high amount of sulfur in the air.  Sulfur and Copper combined make for a very volatile and rapid chemical reaction, one that can easily ruin the quality of a piano string.  To avoid any strings, copper or steel, from rust or any other collateral damage, it is a good idea to clean the strings with a cleaning solution once every now and then.  Anything that will remove any slight black or rusty residue from the strings should suffice.

Now… if you’re unfortunate enough to stumble upon a piano that seems to have lost any hope in being well restored, there are a few options. While buying and replacing strings is the simplest option, it is much more expensive and may not be worth it in the long run, especially if the poor piano is like this due to an environmental factor like the sulfur prevalent air as mentioned before.  You wouldn’t want something like that to happen all over again to a set of brand new strings. Your best bet is to clean them with a more strenuous process.

It is best at this point to remove the strings and separate them from each other. This is easier said than done, however necessary to remove a majority of the rust or residue.  The easiest way to remove most of it is to simply hang the strings on a clothesline outdoors and hose them down.  Afterwards, it is a good idea to pour hot water on the strings and immediately douse them in a generous amount of cleaning material used in items such as ovens.  The boiling water will make the outer surface of the strings warmer, making reactions between cleaning products and residue happen much faster and more spontaneously.

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