A colleague who teaches in a local orchestra program recently texted me because she had seen another string player advise one of her students to scratch the rosin cake before using it. Then the player proceeded to take the student’s bow, and use the end button to produce the scratches! My colleague wondered what I thought of all this.
What I think is that even professional players don’t always understand best practices for their equipment. I certainly learned a lot about equipment that I’d been using for years the first time I went to bow restoration masterclass over a decade ago. The first shock came with a discussion of rosin from the bow maker’s and restorer’s standpoint. The bottom line is that most of us simply use too much rosin. Don’t like the sound we’re getting today? Grab the rosin. Can’t produce a particular bowing technique as well as yesterday? Grab the rosin. Instead, we all need to resist the temptation to use too much rosin, and we need to train our students into this same habit. Overuse of rosin not only doesn’t help our sound, but it actually hinders the sound because so much rosin means that we are grinding an abrasive substance into our strings, into our bow hair, and onto the finish of our instruments.
So, how much rosin is enough? Start by wiping rosin build-up off your bow’s hair onto a clean piece of soft cloth like an old sweatshirt. Carefully wipe off the instrument’s strings, too. Then make just enough passes on your rosin so that the bow hair grips the string. I start with that, and then do two or three passes on my rosin when I can feel the grip slip. We have to help our students judge this until they can manage for themselves. I tell my students to do a couple of passes on the rosin each time they practice. That should give them plenty of grip. DO NOT use water or solvents to clean bow hair. Solvents weaken bow hair. Really dirty bow hair, especially at the frog, is an indication of too much rosin. It’s time for fresh hair!
Now, what about that scratching business? The only time I scratch on a cake of rosin is to get it “started.” Then I’ll take an emery board to the top of the cake, and abrade it just enough so that it will grab the bow hair. Putting actual scratches in the rosin isn’t a good idea because scratching produces minute chunks of rosin, which make for an uneven layer. What is needed is a thin, even layer of rosin on the hair.
Also, bear in mind that, even on some student bows, the end button can contain some silver. This means that scratching a hard surface can cause dents and abrasions on the end button. We should be careful about demonstrating this kind of habit to our students.