|
Polymers in Stringed Instruments
|
|
Violin, Viola, Cello, Bass | Guitar, Mandolin, Lute | Banjo |
Harp | Taking Care of Strings
Stringed instruments are very dependent on polymers for their sounds, since the vibrations of the strings are amplified by their
wood bodies. And we all know (I hope) that wood is composed mainly of the natural polymer cellulose.
The violin, viola, cello and bass fiddle - which make up the strings of the orchestra - are very similar in construction, and all work the same way. A wooden bridge carries the vibrations of the strings into the belly (front) of the instrument, and then the sound is resonated back outward by the smooth back panel. All that wood greatly multiplies the sound volume which is further amplified by the sound holes on the front. And it's all made possible by
cellulose, the natural polymer that makes up wood.
In the old days the strings were made out of stuff called catgut, which is a strange name, since it was really from sheep intestines. This stringy stuff is made of tough
proteins, and though it was strong and vibrated well, it was very difficult to tune because of its sensitivity to weather and temperature. Nowadays strings are made from steel or nickel wire wound with coils of nickel, silver, or aluminum.
The strings are held taught by a set of wood pegs, and the fingerboard where the player changes the pitch of each string during playing is also wood - more
cellulose!
The belly of a violin is usually spruce, which has a density that vibrates well to amplify sound. (Spruce is also used for
piano sound boards.) The back resonator is made of maple wood. The glue that holds the whole thing together is a tough adhesive made from horse hide - another form of
protein. In all, a violin has about 70 individual parts. That's a lot of glue! Recently, a new violin was invented which is molded from a
composite containing
carbon fiber. This revolutionary new design allows the maker to construct a violin from only 20 parts.
The bow which is used to vibrate the strings has a shaft made from
wood which holds a tight arrangement of horsehair. These hairs are formed from
protein and actually have a microscopic scaled texture which gives them friction against the violin strings. They are also treated with rosin so that they will have even better friction on the strings to make them vibrate well. The polymers in the bow also have synthetic alternatives. There are
composites used for the bow stick which are made from glass fiber or
carbon fiber. These materials are light and very strong - well able to handle the tension of the tight bow hairs. Speaking of the hair, there is even synthetic bow hair which can be made from
nylon or
fiberglass, but it is not considered as good as real horsehair for playing.
Guitars and their immediate family are constructed quite a bit like the violins. They have a similar wood body and a sound hole in front, not to mention the bridge that carries the sound of the strings into the
wood. Guitar bodies can also be made of
composites containing
carbon fiber.
Then there are electric guitars with small solid bodies made from a wood like maple. These don't have a normal bridge, but electrical contacts that carry the sounds (vibrations) of the strings out to an electronic amplifier and then to speakers.
Most guitar strings are made of steel. They are made a lot like piano strings. Some are wire while the lower strings have a wire core with another wire wrapped around it. They even make low guitar strings that are wound with flat steel, nickel or silver "ribbon" like violin strings. These metal strings are not polymers, but there is a type of guitar that uses polymer strings...
The classical guitar is different than the steel string acoustic guitar used for pop, folk or country music. You can see the difference in the pictures of both types of guitar. The classical guitar - in the front - looks almost the same but it has
nylon strings and the player uses his fingernails rather than a pick to play it. This gives it a much softer harp-like sound. Also because there is no need for a pick, the classical guitar has no
polystyrene pick guard like a steel string guitar. By the way, guitar pics are made from
nitrocellulose - one of the earliest synthetic polymers, while fingernails are a type of
protein.
The mandolin and lute are instruments similar to guitars but with different body shapes, so of course they sound different than guitars. These instruments have all been around for a long time. In fact, J.S. Bach (1685-1750) played the lute and wrote quite a few pieces to be performed on it during the Baroque period. It has a soft sound like a classical guitar because the strings are made of
nylon plated with a metal like silver. The mandolin, a "descendant" of the lute, has a more "metallic" sound because it has metal strings wrapped in bronze. The distinct sound it makes is very popular in American folk and Bluegrass music, though traditionally it is used in Italian music. Though the lute and mandolin are made of wood, they keep their ancient gourd-shaped bodies more than most of the other stringed instruments. Lutes, and even some mandolins, are rounded in the back. That's because a long time ago, these types of stringed instruments were made out of large gourds which were cut in half, then hollowed out and covered with the front wood piece. And - like wood - gourds are plant material, another form of
cellulose.
The banjo has a design unique among stringed instruments plus it also has some interesting polymers in it. The design and construction came from Africa where instrument makers decided to use the standard gourd back as a resonator, but instead of a wood front with sound holes as the amplifier, an animal hide "drum head" was used.
These heads could be made from the skins of gophers, possums, beavers or even cats! The back resonator on a modern banjo is a curved piece of
wood - anything from mahogany to rosewood. The neck is made from various woods also - mahogany, maple, rosewood - while the finger borad is made from ebony. Still today some people play hide heads on their banjos, but these are now made from calfskin - a form of
protein - and are greatly affected by temperature and weather. They also give a "darker," more mellow sound preferred in more old-timey folk playing. The newer heads are preferred for bluegrass and other newer styles, and they are made like modern drum heads, usually from the plastic
polyethylene. They can be clear or frosted with different finishes, or even colored. Each treatment of the head causes a slightly different tone.
Like the other members of the string family, the banjo uses a
wood bridge (maple and ebony) to transmit the vibration of the strings to the head. Surprisingly, changing the bridge on a banjo is the best way to quickly change the tone. Traditionally the strings were made of gut - like the lute, guitar, fiddle, and other stringed instruments- but now they are metal wound in bronze like mandolin strings.
Harps are made in a variety of sizes and sounds with different numbers of strings. The frame of the harp is formed by the column, the sound board, and the neck, where all the strings are connected and held tight by the tuning pins. All these major parts of the harp are made of
wood. The sound board resonates to amplify the sound of the strings and is usually made from spruce. This is supposed to be the best type of wood for sound boards. But the sound board can be made of different kinds of
wood as can the rest of the frame.
The strings are traditionally made of
sheep gut like most other older stringed instruments. Some harps still use gut strings or strings made from synthetic gut. But most harp strings now are made of
nylon monofilament like those on a classical guitar, or they can be a
nylon core wound with more nylon or a metal such as bronze or silver for a brighter sound. Large pedal harps that need an octave of deep bass strings might have wire wound strings made of steel on the low end. And there are a few folk or lever harps that have all their strings made of wire, a bit like a piano.
One of the best and most important things you can do to care for a string instrument - as with any other instrument - is to keep it in a sturdy case. The case should have a tough outer shell. A simple black student case is made from
ABS resin which is very strong. The more complicated models can have shells made from resins or
plywood covered with tough
nylon like the one in the picture. The various straps and pockets are also made from nylon. The inside of string instrument cases can be made from
polyurethane foam cut to the shape of the instrument, or they can be molded to the instrument shape and covered with a soft
fabric like felt or velvet.
One important thing that the violin family needs is the regular application of rosin to the bow hair. This slightly sticky stuff coats the hairs and causes friction between the bow and the strings. And without friction, there would be no sound. Rosin is a
natural resin made from the sap of pine trees. The sap is boiled and refined and then poured into molds to cool. Each maker of rosin has a different recipe. Some include ingredients like beeswax and other kinds of tree sap to give the rosin certain properties. There are different types of rosin, depending on the time of year the sap is harvested and depending on what other ingredients are added. Darker rosin is more sticky. This is best for the big bass fiddle. The lighter amber-colored rosin is better for violin, viola and the cello. There are also different types that are better for different seasons of the year.
Because things like skin oil, sweat and rosin, which can flake off as a white powder onto the strings, bow, and body of instruments, the instrument should be cleaned after each practice. The best thing for this is a soft dry cloth.
Cotton is a good materal for this. There are also cloths made from
microfibers of
polyester and
nylon. These tiny fibers are good because they are too small and fine to do any damage to the instrument's finish. A cloth should also be used once or twice a year to restore varnish and polish the wood.
Another handy device for string instruments is a humidifier. This device helps protect the delicate wood and the glue joints from drying out and cracking, especially in the winter. Humidifiers can have a plastic casing such as
polystyrene or a
rubber tube with a
foamy spongy polymer inside. The sponge holds the water so that it won't drip out. This is very important since some humidifiers are actually kept inside the instrument when it is not being played. They make these for both fiddles and guitars. Another type of humidifier (seen here) is simply held inside the instrument case with Velcro. Thus, whenever the instrument is not being used, it stays at the proper humidity. You can even get a special gauge that measures the humidity inside the case.
That's enough about the string instruments. Take a look at the reference sources for this page (below) or click on a different link to choose another type of instrument to look at, or go back to the Macrogalleria or PSLC main pages.
Sources for this page | HOME | Instrument Index | Macrogalleria | TOP
