If they are made of wool, it is best to dry-clean them. If they are made of cotton it is best to wash the beged by hand, and not wash the strings. The problem is that the strings are normally made of wool, which is easily damaged in the wash. When the strings must be cleaned, immerse them in ammonia and gently wash the ammonia out with lukewarm water. The solution of putting the strings in a bag also works, but does some damage to the strings.
