Under the strings of tanpuras, which are unfretted (unstopped), and occasionally under those bass drone strings of sitars and surbahars which are seldom fretted, cotton threads are placed on the "javari" bridge to control the exact position of the node and its height above the curved surface, in order to more precisely refine the sound of "javari". These cotton threads are known in Hindi as 'jīvā', meaning "life" and referring to the brighter tone heard from the plucked string once the thread has been slid into the correct position. This process is called "adjusting the "javari"". After a substantial time of playing, the surface directly under the string will wear out through the erosive impact of the strings. The sound will become thin and sharp and tuning also becomes a problem. Then a skilled, experienced craftsman needs to redress and polish the surface, which is called "doing the "javari"" ("'Javārī Sāf Karnā' or "Cleaning the Javārī'").