Pirastro violin string cleaner can help to remove old rosin deposits that build up over time on strings. Applying sparingly to a lint free cloth and then wiping down the strings can give them a new lease of life. Obviously strings do need to be replaced from time to time but this liquid can delay that. Think of it like when a printer runs out of toner, and you give it a shake and get a few hundred more pages - this is the same principle!