A while ago, somebody asked me a question about guitar strings, and I promised that I'd post a tutorial here to discuss them in a bit more detail. It's taken me a while to get around to writing this (so if it was you that I told it'd be a few days, I apologise) but here goes...
Guitar strings are made from a number of different materials. An acoustic guitar may have steel or nylon (or even, occasionally, gut) strings. Electric guitar strings are always made of steel, but it't not that straight forward.
The thinner a string is, the higher the pitch. The thinner strings on a guitar are plain steel (or nylon, or whatever) and hence are known as 'plain' strings. The thicker strings have a solid core, but this has another wire wrapped tightly around it - hence this is known as a 'wound' string.
On an electric guitar, the top 3 (usually it's the top 3, but sometimes it's just the top 2) strings are plain steel (or a nickel/steel alloy). The wound strings have a plain steel core with steel/nickel winding. The use of magnetic metals is necessary so that the pickups can detect the string movement. On a steel-string electric guitar it is far more common for the windings to be phosphor bronze, which provides a better acoustic tone. This isn't magnetic (so you can't use that type of string on an electric guitar) which is why the pickups on steel string electro-acoustics are piezo rather than magnetic.
On a classical guitar, the strings are made of nylon. Again, the thicker strings are wound with metal, but these are still classed as nylon strings, as the string core is made of nylon.
You may come across some alternative materials/coatings for steel strings. Some people have a nickel allergy, and playing conventional strings could cause irritation on their skin, so some manufacturers make strings with a low/no nickel content. Also, strings will corrode with sweat, etc. so there have been a few attempts to market strings with coatings intended to protect the string - such as gold, chrome and even 'Gore'Tex'.
String gauge refers to the thickness of a string, and are generally measured in thousandths of an inch. Like probably the majority of electric guitar players, I play a set of '9s'. That is to say, the 1st/top E string is 0.009" thick. The full set of gauges for a typical set of strings is 9, 11, 16, 24, 32 and 42 (which means that the thickest string is 0.042" inches in diameter).
There is a trade-off to be made between playability and tone. A thinner (lighter) set of strings may feel more comfortable to play but as there's less metal vibrating the tone will be a little weaker. Also, as they're thinner, the strings are also more liable to break, especially the thin top E string. If you really crave lightness of gauge, you might want to try a set of 8's, but personally I find these feel a bit too flimsy.
Thicker (heavier) strings can give more tone, but they can also feel a little more awkward to play (a thicker string needs more tension to tune to the same pitch as a thinner string). If you're into rock/blues, where string bending is a big thing, then this can be an issue, especially if your fingers aren't too strong. A common apporach is to use a 'hybrid' set with, lighter strings on the top and heaver gauge (maybe like you'd find in a set of 10s or even 11s) on the bottom. This gives a good compromise, with more comfortable lead playing and string bending on the top strings, and a fuller sound to chords for rhythm playing.
Jazz players especially often opt for a heaver gauge, maybe something as heavy as 13s. These give a nice full sound, and jazz players aren't into the huge bends that rock lead players are, so the extra tension isn't an issue.
On an steel string acoustic guitar, gagues are usually a tad heaver than on an electric. If you play 9s on an electric then you'll probably end up with10s or 11s on an acoustic.
Nylon strings are measured in terms of tension rather than thickness (i.e. 'normal tension', 'high tension', etc.) but it comes back to pretty much the same thing.
If your guitar has been set up properly, then the strings should sit at a comfortable height above the fingerboard, the neck should be straight and, if you have one fitted, the tremolo should be balanced correctly. However, if you change your strings to a different gauge, then you'll find that you (or your local guitar repair guy) will need to make a few adjustments.
You wouldn't normally expect to change string gauge that often. Probably the most common reason will be if you've been playing a lot and your fingers are getting stronger - to the point where your current strings just feel too light, and you want something a bit heavier.
When you change string gauge, the amount of tension in the strings will increase or decrease, depending on whether you've moved to heaver or lighter strings. If you have a tremelo, then the strings inside the body which balance this against the string tension won't be as balanced any more. You'll probably need to adjust these (or add/remove) a spring. This can take a bit of trial and error until you get the balance just right.
Different gauges of string vibrate more freely than others, and so you may need to raise or lower the action to get the most comfortable playing height above the fingerboard without the strings buzzing against the fret wire.
Most significantly, a big change in tension can cause the neck to bend. The tension of the strings is balances by a metal rod inside the neck, called a truss rod. This can be tightened or slackened to compensate for string tension, but this should be done very carefully. If you make a mistake when adjusting a truss rod, then you coulkd permanently damage your instrument. If in doubt, take it to your local music store and let a professional take care of the job.
How useful did you find this tutorial?