Between your instrument strings and the bow hair is something vital, the rosin. Too much or too little, applied the wrong way, can impair your playing.
The beginner violinist may think a small disk of coniferous tree sap, rosin, plays a minor or even unnecessary role in the creation of music. Au contraire! The right rosin, applied with expertise, can significantly affect how the instrument is played and the sound it creates.
The end goal of having just the right amount of rosin is to create warm, rich tones, with just the right amount of friction that enables smooth movement of the bow over the strings.
But it’s possible to have too much or too little rosin, or you might mishandle the rosin in ways that are detrimental to the bow or the instrument itself.
So let’s break that down:
The Goldilocks of Rosin: too much, too little – or just right
It IS possible to play without rosin on your bow but not advisable. It’s more work for the violinist or cellist who has to press harder on the strings. And even with that the results are a hollow, pale sound. Add a little (but inadequate) amount of rosin and the sound will improve. But the friction the rosin is intended to create will tend to be spotty, as will be the music.
Too much rosin will make the bow feel stickier as it moves across the strings. Excess rosin can generate a cloud of rosin dust as you play, and the sound will be harsh and scratchy. Rosin debris will fall onto the surface of the instrument and, over time, can damage the varnish and the wood.
For this reason, when working with fine instrument bows and fine stringed instruments, understanding of the proper rosining techniques is of utmost importance. The right amount of rosin allows easy movement of the bow, rich tones, and no excess. As a rule of thumb, it typically takes four or five strokes of rosin on the bow hair to achieve this.
Correct handling and application of rosin
It also matters how the rosin is applied. There are a few steps to take:
Tighten the bow. Slack hairs will accept the rosin unevenly and it becomes possible the rosin will touch the bow wood (not good).
Don’t touch the hairs. Natural skin oils are bad for the bow hairs because it prevents the rosin from binding.
“Activate” a stick or disc of rosin when it is new. By this we mean scratch it lightly with the edge of a quarter to slightly roughen it. You only need to do this when the rosin is new.
Cover the entire length of the bow hairs, from end to tip, for even playing.
Rotate the rosin as you apply it. This is to avoid creating grooves in the rosin that cause it to break before it’s used entirely.
Wipe off excess rosin on the bow stick and the strings after playing. You want an even distribution and to avoid caking.
A final note on which kind of rosin is best, as well as the quantity: That depends on the ambient temperature and humidity, and the type of stringed instrument being played. Violins and violas, with smaller strings, need lighter (in color, density and stickiness) rosin. Darker rosins are stickier, heavier and more suited to the cello and bass. With higher temperatures and humidity, too much rosin can get stickier. And of course, vigorous playing will heat up the bow and strings as well. Players need to pay attention to all such conditions and how it affects the rosin and their music.
When in doubt, take a trip to your local violin shop and ask the local expert.