The number of types of strings increases progressively, and each guitarist has his own preferences, which are linked to the kind of guitar as well as the kind of music that he plays.
In the past, guitarists used very different strings from the current ones. In the middle of the XX century, for the majority of the time, they used strings made of pork belly, and sometimes they were made of steel as in the case of Agustín Pío Barrios (Mangoré).
That all changed with the introduction of nylon or plastic, which is also a well-known name of this artificial polymer. Today, it is very common finding nylon strings for the trebles strings (in many cases, black ones for flamenco) and a nylon-braid with copper for the bass strings.
Since the introduction of nylon, there have taken place a series of innovations that widen the guitarist’s options. Nowadays, we can also find carbon or titanium strings. All of them with different gauges, hardness in materials, and with quality and laser systems, which enable an extraordinary result.
The string gauge, combined with the material used, is crucial to establish the tension that will be exerted on the guitar.
To get an idea, in the case of Alhambra, we use in our guitars D'Addario strings (EXP 44 Extra Hard Tension). It is a set of strings made of nylon which provides a hard tension.
If we take the first string as reference, it has a gauge of 0.029''. In the market, we can find other strings with high tension, whose gauge could vary even 0.030''.
On the other hand, changing the materials, the proportion of size and tension also varies. Perhaps, the most striking case with respect to the difference in the proportion between gauge and tension takes places using carbon, where we find gauges about 0.023'' and hard tensions.
Regarding the results of the different materials, we could observe brighter colors, more projection and a major volume if the string has a harder tension. This also happens with carbon if it is compared with nylon.
In contrast, using titanium we find a more delicate touch and pinkish colour which, regarding the sound, provides coloured nuances to the sound that could be described as flashes. Respecting the width of titanium, it is similar to nylon.
In many cases, manufacturers combine strings made with different materials in order to optimize to the maximum the development of the guitars. It is quite common to find third raw strings with carbon. Generally, the third string (G) is the weakest sound, having to "break" the note sometimes for trying to make it sound. It could be solved by means of using a string with a harder tension or a carbon one.
Have you experienced this problem with your guitar? Test it. Use a third of a carbon string and observe if it improves the string’s "sustain".
Regarding the bass strings, they consist of nylon filaments coated with a copper wire. Normally, they are silver, but there are also golden ones.
Depending on the brand, we can find different times for tuning the string. Using some manufacturers, we could have our string ready in our guitar in just one day.
In any case, we must not forget that the most important thing is to test it, test it and test it. Using some indications and with experience, we will find the best strings for our guitar and our kind of interpretation.