I chose this cleaning fluid after I wasn't able to simply wipe the collected rosin from various areas of my violin. Rosin is such good yet annoying stuff. It gives you your tone on your violin, but it gets everywhere even when you're using it sparingly.
The Viol fluid is the answer to your problems. It's always good to try the fluid on a small discrete part of your beloved violin to make sure that you don't have any negative effects. After that, just a drop goes a really long way and you can clean all the worst parts of rosin deposits from your instrument. The bottle is quite small, but 1 drop really does go a long way. It's really tempting to use lots of it and to try to polish your instrument back to a high gloss, but I think this would be a really bad thing to do especially on older violins. My violin is only a couple of years old, yet I still try to only use this cleaning fluid when I really need to.
It's really good to treat yourself to a super deluxe micro fibre cleaning cloth too. You can generally wipe most of the rosin off and then use this Viol just when you really need it. Your violin owner in a few hundred years time will really appreciate it and you won't have worn away the finish with over polishing.