Reasons for Santoor becoming tuneless:
Suppose that the instrument is being kept in an environment with fixed position, temperature, and moisture. Now if only one of its strings becomes tuneless randomly, it is probably due to the turning of normal saddles or bad form of the nut. However, if the whole tuning goes up or down, the problem may be the bad placement of the main bridge.
When to change the strings:
For usual users: Once in about two years
For professional and precise users: Once in each 4-12 months
The Reason of strings becoming dark:
Santoor strings can get oxidized in the presence of oxygen and moisture. This will change the color of strings. However, the strings of some Santoors kept in the same conditions darkens more. This is due to the exchange of electrons as well as the chemical ingredients of the wood and the strings. In order to clean the strings, emeries are used.
Why strings should be changed?
Santoor strings erode in presence of high pressure and the abrasion of metals in the nut and bridges. This will lead to the corrosion and tapering of the strings, which may make it hard to tune the instrument in a desirable way.
Why moisture is detrimental to Santoor?
We all know that Santoor should not be exposed to moisture. But why? Before building Santoor, the wood is still wet and there is water in the wood. Santoor builders dry the wood to make the instrument. This causes the volume of wood to decrease and reach a certain point. Now, if Santoor is exposed to moisture, the volume of wood increases, more pressure will be on strings, and the instrument will get damaged.
Why do yellow strings change more often than white strings?
The pressure of yellow strings is less than that of white strings. This causes their tune to go up and down more than that of white strings. This may also happen in case the environment temperature changes. To avoid this issue, especially during concerts, we suggest you to take the instrument to the concert hall so it can get used to the temperature. Then, you can tune it.