Maintenance of plucked string instruments

Francisco Hervás


The care of plucked string instruments requires our attention in some simple tasks that will help ensure that their conservation and operation is correct. The descriptions mentioned below will help carry out the necessary care to keep our instrument in good condition.

Correct winding of the strings.-

The strings must be wound on the pegs correctly, that is to say, that in the winding do not mount any of the turns above the others or are disordered and above all that do not press the wall of the head (in the case of lutes and theorbo) nor the base of the pegbox (in the case of vihuelas and guitars). In this way we avoid that the pegs are tightened excessively when being “engulfed” by the peghead due to the pull of the strigs on the peg (figure no. 1). We can not even imagine the force with which the strings can produce such an effect. This also makes it very difficult to turn the pegs and therefore the act of tuning the instrument is complicated and unpleasant.



Sometimes, and especially with the theorbs and archilaúdes, we can find the problem of not having enough long strings for the basses. The solution is to tie a piece of excess string at the end that corresponds to the pegbox, provided that the length of the string gives enough for the knot to be in the section between the nut and the peg as this will not affect the sound. The appropriate knot is described in fig: No. 2.



Pegs problems.-

A very common problem that the pegs can present is that they are tightened in such a way that it is impossible to move them and that there is a danger of breaking them when trying to rotate them with force. This usually happens when the instrument has been unused for some time, coinciding with a change from a dry season to a wet one, for example between summer and autumn, if the instrument has not been sufficiently protected against the increase in environmental humidity that usually accompanying this change of season. The explanation is that the pegs absorb moisture, swell and tighten excessively against the pegbox, making it very difficult to move them. If we check that they do not rotate as usual, it is useless to try to force them, since we could even break them by excessive twisting of the fibers of the wood. An effective solution is to apply hot air with a hair dryer so that the pegs lose moisture and the pressure exerted on the pegbox ceases. Another way that can work if the pressure is not excessive is to give a dry tap on the tip of the peg with a suitable object, ideally a wooden bar with the flat tip and diameter somewhat smaller than the thickness of the tip the peg or some other object with similar characteristics, so that when hitting it do not damage the pegbox. To carry out this operation, we will give a dry tap to the aforementioned bar against the tip of the peg, with the help of a small hammer or some object that replaces it and the peg will be released without further complication. We will have thus prevented the breakage of the peg, something that would have happened inevitably if we tried to force it by turning it. This problem is minimized when the pegs have a rounded tip, with this precaution the pegs is prevented from absorbing excess moisture and embed into the pegbox.

In order to maintain correct operation of the rotation of the pegs and to keep them in their position after tuning, it is necessary that the adjustment between the peg and the pegbox is exact. The maintenance of this adjustment is very important and must be done by a luthier when necessary. However, the operation of the pegs can be facilitated by applying graphite to the rubbing areas, simply ‘painting’ them with a preferably soft pencil (6B to 8B). Graphite is a good solid lubricant that helps the pegs slide in the tuning and, at the same time, allows the peg to be fixed after moving it, besides, it practically does not add any thickness since the applied layer is micrometric, thus the adjustment between peg and pegbox is not altered at all. However, it is convenient not to apply too much graphite since the peg could slide excessively and detune the instrument. There are other products that can be used for the same purpose, such as Marseille type dry soap, pegs paste, etc., although I recommend graphite as the most suitable.

Tensed of the frets.-

A disadvantage of gut frets is that over time, in addition to deteriorating, they become loose due to changes in environmental humidity or, simply, by distension of the material. There is a way to tighten them without resorting to the typical small folded paper block or toothpick that we have all seen use or have ever used. It consists of dragging the fret towards the pegbox to release it and in that position try to pull with our fingernails the ball of the end of the fret on which the other end is knotted. The correct extrem ball we will identify simply because we can extract it, while the other end (the one that knots) does not allow us such a thing. Once this step is achieved, the next step is to cut the end of the fret under the ball, burn it again to generate a new ball, and finally drag the fret it to its place, where it will now be firmly secured. Although this operation requires a certain skill, once learned it is easy to perform and with this we will be able to give tension to the frets again and this will not move from its place. In case the fret knot is too tight, we can use small pliers to perform the operation.

Regulation of the fret setting.-

Changes in ambient humidity conditions cause alterations in the height of the strings in the instruments (strings action). This is because when the relative humidity of the air increases to levels of 70-80% or more, for example on rainy days of autumn and winter, the soundboard of the instrument rises and with it the bridge also increases, increasing the strings action. The opposite occurs with dryness, when in summer, or by the use of heating in winter, the humidity decreases to levels below 45%, then decrease the usual height of the strings. This fluctuation can make the instrument uncomfortable to play in the first case and fret buzzing occur in the second. To solve this problem it is necessary to modify the height of the nut and the sizes of the frets, being convenient that this operation is performed by the luthier, especially if it is necessary to lower the height of the nut, a delicate operation that requires the hands of a expert.Normally the sizes of the frets go from highest to lowest from the nut along the neck to the body of the instrument, we could say that this is the ‘standard’ fret setting. When there is an alteration of the height of the strings Action due to changes in environmental humidity, it is necessary to modify the sequence of thicknesses of the frets.

In the case where the nut is has shod with strips of paper, the task of lowering the height of the strings is simpler and consists simply of dislodging said paper strips. Once the string height is correct (approximately 3,5 to 4 mm between the fingerboard and the strings in the area of the neck with the instrument case) It will be necessary to modify the thicknesses of the frets to adapt them to the new height of the strings. In general, it is enough to use equal calibers for all the frets, but in more extreme cases a more drastic modification of the thicknesses may be necessary, being necessary to put a set of inverted calibers, that is, the first will be the thinnest and the last the thickest, this will allow us to lower the eyebrow considerably and with it the height of the cords until it is correct. In any case, It will be advisable to make a sound check with each fret that is changed to verify that there are no buzzings. In any case, the latter is a sign that the problem is more serious than normal and the most advisable thing is to take the instrument to the luthier in case a larger intervention is necessary.

This operation is also important to prevent the instrument from moving further and increase the angle of the strings, since when the height of the strings has increased for the reasons stated above and it is not remedied, the tension of the strings also increases, and the instrument received greater traction between the bridge and the pegbox, being able to cause the handle to curve forward or the top to deform excessively.

In the opposite case, when the environmental conditions are dry, the soundboard of the instrument low and it happens that the instrument produces fret “buzzing” when you play, then it will be It is necessary to recover the height of the strings and for this you can proceed in two different ways:

1.- Supplement the nut with paper strips to increase the height of strings respect the first fret approximately in 2 or 3 tenths of a millimeter and changing the successive frets with new calibers that go decreasing from the initial thickness at a rate of 0.5 tenths of millimeters each time, making a sound check after each change .

2.- Increasing the height of the strings in the bridge. For this it is enough to supplement the bridge with a wooden sheet that is placed between this and the strings, with the precaution of pulling the strings a little outwards when tuning the instrument, this achieve to slightly increasing the height of the strings and eliminating the problem.

If necessary, the two techniques can be combined. Once the correct height of the strings is reached, which will probably coincide with the height defined above, the instrument will be in optimum conditions to be played with comfort.

The nut slots.-

The nut slots are designed to establish the separation between the strings and that this are correctly aligned in their trajectory towards the pegs, without there being any torsion, therefore it is necessary to take care that the winding of the string is adequate for to keep the correct alignment. It is necessary, therefore, to take this into account to avoid unwanted twisting of the strings, which could also cause them to come out of the nut slots when we play with some force on instruments with little angle between the neck and head as vihuelas, guitars, theorbos or archlutes; or that the pegs are suddenly released by the lateral pressure exerted by the strings when they are badly wound.

Another problem that can be present in the nut slots is a mismatch that manifests itself when the string is played open, producing an effect similar to the typical “buzzing” noise of the frets. This buzzing of the nut occurs when the strings do not support correctly in the slots of the nut, It is not well done, and it is usually more frequent in the wound strings, as we can see in the example shown in figure 3. Sometimes it is very difficult to detect because it is confused with the buzzing of frets, in this case it can be verified removing the first fret to discard that this is the one that produces the noise, so that if this persists, it is undoubtedly caused by the nut slot. We can see in the drawing that there is a small mismatch in the slot just at the edge of the nut that at first sight is very difficult to detect and that must be corrected so that the string emits a clean sound. This operation should preferably be carried out by an expert since it is a delicate adjustment that must be carried out with the maximum accuracy.


The buzzing noise produced by playng an open string may have their origin in the case already discussed, related to the eyebrow, or be produced by friction the string with the first fret by the vibratory movement, in this case it is enough supplement the eyebrow with a or more strips of paper until the buzzing disappears.

When the buzzing takes place in all the frets, it may be due to an insufficient height of the strings in the bridge, which may have been caused by a decrease in the relative humidity of the environment as already mentioned above, or an excessive deformation of the soundboard due to the action of the tension of the strings. In this last case it may be necessary the intervention of the luthier to recover the level of the top, although in the mild cases it is enough to supplement the bridge with a sheet of wood that is placed between it and the strings, with the precaution of pulling them a little outwards when tuning the instrument, with this you can slightly increase the height of the strings and eliminate the problem, as already explained above.

Maintenance of the soundboard.-

In general, the soundboard is usually not varnished, which requires special care to prevent dirt and deterioration. For this it is convenient to maintain its waterproofing by applying a layer of wax with a soft cloth from time to time. In the trade there are preparations of wax for furniture that go well to the effect, basically they are composed of beeswax and turpentine essence. The wax gives the lid a protective layer while cleaning the dirt that may have, should be applied in small amounts extending it in passes to the wood thread and then rubbing with a dry cloth. Microcrystalline wax can also be used with similar results.  It is convenient to also apply linseed oil to the fingerboard coinciding with the changes of frets and strings. This cleans and nourishes the fingerboard wood.

Important to keep in mind is that, in case there is a crack In the wood of the top, wax should not be applied, since it can penetrate the groove and make it very difficult to repair. The break should then be covered with transparent adhesive tape to prevent dirt from entering and bring the instrument to repair as soon as possible.

Problems with bars of the top.-

It may happen that one of the bars of the soundboard detaches at one of its ends, which causes a noise similar to the ” fret buzzing” usually when a note is played of the low range of the instrument. If this happens it is convenient to locate the loose bar, this is done by exerting a slight pressure on the edges of the lid looking for the place where we will notice a noise that will announce the location of the loose bar. Once located, if for some reason we have to use the instrument before we can take it to repair, we can temporarily secure the bar using a small wooden blok or a similar material of approximately 10 x 10 x 5 mm. (It may be worth a piece of cardboard folded several times), which we will hold in the rib of the instrument with a piece of adhesive tape, just over the end of the bar in question (figure  4). The pressure exerted by the taquito will make the bar stay in contact with the rib and the noise ceases. However, it is very important to bring the instrument to repair as soon as possible, otherwise the bar will also begin to detach from the harmonic lid progressively sinking, which will make the repair more complicated.

(Fig. Nº4)

Tension of the strings.-

The optimal strings tension for an instrument must be determined by the constructor of the instrument, according to its own criteria and in accordance with the particular characteristics of the instrument. Only experienced musicians can modify this tension moderately to adapt it to their needs, always respecting the limits set by the luthier and always bearing in mind that they are usually very light instruments subject to high strings tension.

Is not can to establish a standard string tension for any instrument because it will always depend on its specific characteristics, however the most usual values are around those expressed below:

For double string instruments (lutes, vihuelas and guitars) from 3,2 to 3,6kg for the 1st string, from 2,6 to 2,8kg for the double strings in unison and from 2,5 to 2,6kg in the octaves.

For theorbos with simple strings between 3,5 and 4,0kg in the shor set and something less for the basses (3,2 to 3,8kg)

For the archlutes, the tension in the short set similar to the lutes and the basses as in the theorbos.

It is convenient to keep in mind that the tiorbas and archilaúdes are subjected to the action that the strings exert on the stended neck of the basses, being able to reach that this one curves more than the normal and that the strings exert an excessive traction in the bridge, due to the increase of the angle formed by the strings with the plane of the soundboard. This could cause deformations in the top and even get to take off the bridge. To avoid this problem it is advisable to check that the height of the basses at the end of the fingerboard (in the area of the nut) is between 5 and 10 mm. and do not exceed this maximum value (Fig. Nº5). In case of being superior, it will be necessary to lower the height of the nut of the basses to correct the excess and thus avoid major problems.

(Fig. Nº5)