Playing stringed instruments means that we have to maintain the strings from time to time. Sometimes they break and simply need replacing. This article should explain everything you need to know about strings.
There are two different materials for the strings for the types of instrument on these pages - Nickel and Phosphor Bronze, and two types of string. Thinner strings tend to be 'plain' i.e. a single piece of wire, and 'wound' which are a single piece with another tightly wound around it. In general, heavier, larger diameter strings are for lower notes and lighter, thinner strings are for higher notes.
Actually nickel plated steel or 'steel strings', they are shiny silver when new. Plain strings are Nickel, wound strings can be either Nickel or Phosphor Bronze. These can be used on Mandolin, Mandola, Mandolin Banjo, Banjolin, Tenor Banjo and Bouzouki.
Immediately distiguishable by the goldy bronze colour. Only available as wound strings, they give a 'brighter' sound and are often used on the wooden instruments i.e. mandolin, mandola and bouzouki.
Loops or Balls. Typically, all the instruments on these pages have tailpieces which have a hook for each string. Therefore they need 'loop end' strings to hook over.
Ball end strings usually slot into a hole underneath a peg and are common on guitars. You can put a ball (actually a brass ring) into the loop of a 'loop end' and twist the loop another couple of turns. If you break a string or change a string with a ball end, save the ball! Taking a ball out is harder but is possible - unwind the twists a little and ease out the brass ball. Often though, you end up snapping the loop! Other than that, there is no difference between them.
The string weight or gauge is the number on the packet and most people know of string gauges in thousandths of an inch. e.g. a '10 gauge' string is 10 thousandths of an inch diameter or 0.010 inches. Plain strings are available between 7 gauge and 26 gauge and wound are available between 20 gauge and 59 gauge. Note the overlap in the middle between 20 and 26. Anything below 10 is considered 'light' and probably above 40 is considered 'heavy'. The set of strings you use on a instrument affect its tone, playability and set-up. The bridge and nut have grooves for particular gauges of string to seat properly and really should be changed if you contemplate changing to a substantially different set. The other important thing to remember is that strings are under tension and put a stress on the instrument. Some cope better with increased stress than others. It is not unknown for an unwise restringing to pull the instrument apart!
Imagine a string pulled tight between two posts. The string will try to pull those posts inwards so that the string collapses to 'rest' or an untensioned state. The tension is how much resistance there is to that force to keep the string taut. Your instrument is pretty amazing at keeping that tension constant all the time. It's all in the construction. What factors affect tension? All of these will increase the tension on your beloved instrument all else being equal:
So if you go up to heavier strings, or go to a tuning that takes the pitch of any string higher, you will put more stress on the instrument. Most modern instruments have a 'truss rod' running though the neck and this can prevent the neck warping under tension, but it will not prevent the body collapsing! Banjo instruments are more robust in this respect because of the way they are made. If the neck can stand the tension, the body usually can.
To keep the amount of tension in a reasonable range, certain instruments with certain tunings have a typical length of string. The scale length (length from nut to bridge - the length of the free vibrating string) and the weight of the string are the best compromise for that particular tuning.
Strings will deteriorate with time. The tension will take it's toll and the acid in the sweat from your fingers will also affect them not least with discolouration. The strings will become increasing difficult to tune 'clean' and will sound duller. It's a gradual process and some people never notice! If you play regularly, change your strings every 4 - 6 weeks. Wipe the strings down with a cloth after playing and if you are leaving the instrument unplayed for any length of time, slacken the tension on the strings.