THE CURVE AND THE FORCE

In the previous blog I tried to explain you how to recognize a properly done curve. This week we will start to deepen another topic, this one as well strictly related to the curve: i.e. “the force  of a bow”

Proper quantity of curve in a violin bow

When a musician keeps a new bow in his hands for the first time, very often and, sometimes even before he starts playing with it, the first question is “How much does it weight ? “. In fact it is a common thought and belief of any musician that the bow weight represent a parameter to determine its force.

Truly speaking, the weight is the most variable aspect in a bow. The weight is decided upon the mechanical features of the wood that will be used for the bow itself. We take a violin bow as a reference. The French school, after years of development, has fixed for the violin bow a reference weight of 60 grams, but beware, I said “a reference weight”.

To say the truth the weight of a bow is determined by the bowmaker, once the adequate strength level is reached, he stops and doesn’t remove wood any more, no matter what the weight of the stick is. It is possible to find a smooth violin bow of 62 g that gives its smoothness to the lower quality of material used, and another one of 57 g, that can be very tough. Furthermore the mountings can strongly affect the total weight of the bow.

Between a mounting in silver thread having a diameter of 0.30 mm and another one in whale tooth there are almost 3 g difference. The same can be told between a button in 3 parts (silver, ebony, silver) and another one completely made of silver, or between a frog in ebony, turtle or ivory. In a nutshell, all components play their  role in the composition of the weight, changing it sharply but leaving the force  practically untouched.

We disregard for the moment the fact that no musician, while playing a bow, can also perceive the balance, i.e. the weight on the point. We deal now with one of the two components that can sharply change the bow force: one is the wood quality, or better the tension of its fibers, the other one is the “curve”.

Even if the curve is rightly done, that is to say without flat or uneven areas, it is necessary to give a right curve in the right quantity. To understand if the quantity is the adequate one, one has to take as a reference its maximum point, i.e. the part of the stick next to the hair. For instance, viola and violin bows, with a stick in a rest position, in the maximum point the wood must touch the hair. In case of a cello bow, the distance should be 2 mm while, in case of  a double bass bow,  it is 4 mm.

Proper quantity of curve in a cello bow

It is obvious that every wooden piece has its own history and consequently there may be slight differences in these reference parameters. If, for instance,  you find a bow of your liking and have the wish to have it a little bit stronger, it will be easy to ask the bowmaker to take away some curve and, if by a magic touch, the bow will become stronger.

Obviously we refer to the beginning of mechanical physics: the lesser is the curve you give to a bow, the stronger it will be; at the same time its “jumping capacity” decreases.

If you ever hold a baroque bow, you will perfectly understand what I mean. Just think to play with the very first bow that had the curve in the opposite direction of the modern bows. You could not even dare to think to “balzato” but also to the concept of the weight on the string.

In fact,  the sound differences with these bows were possible only by the technique of the “hair tension” that was carried out with the fingers and consequently, changed as per one’s liking during a performance. Increasing or decreasing the hair tension, the tension of the wooden fibers was changed as well as the sound intensity.

Resuming all the speech, it is possible to modify a bow force  taking some curve away but this work has to be carried out by a skilled bowmaker that knows his work thoroughly, it has not to be excessive; we can say we can divert from the fixed references over 1-1.5 mm,  no more. For the violin bow the sizes ranges from 0 to 1 mm max.

Giving too much curve may  create serious problems to the mechanic of the bow itself and in one of the next blogs I will explain why this could happen.

So long

Paolo