This article is a sub-article of the Bowspeed, Pressure, Point of Contact and Bowhair page. Bow-pressure and bow-speed are so intimately related that this page needs to be read together with the page dedicated to Bowspeed.
Bow-pressure corresponds to two elements in painting: darkness and paint quantity (thickness). When we play with the lightest bow pressure (flautando), we are painting with watercolours (French impressionist music). The more bow-pressure we use, the darker our sound will be and the more paint we will leave on the canvas. Lots of bow-pressure corresponds to thick oil painting (Brahms and much Germanic music). And when we play with maximum pressure we are applying thick cement!
Edible analogies are as good as artistic ones – especially for children. A bow stroke can be usefully compared to the movement we use to get a spoon full of ice cream (thank you Irene Sharp for this one). The more you press, the deeper it goes and the more you get! But if you are too greedy and try to go too deep, the spoon gets stuck, especially if the ice cream is too cold. Having a good instrument is like having the ice cream at just the right temperature – you can get a big fat spoon of it at each bow stroke with little effort!
A musician is not just an artist. We are also engineers, and not just sound engineers. Sound is like a physical material that we can produce in any density (viscosity) we want, from molten lava to the lightest gases. Bow pressure gives this viscosity and density to our sound …… but be careful: when the pressure is too much, the sound’s viscosity also becomes too great, and our gorgeous thick stream of molten metal can solidify into something rough, sharp and ugly (like lava rock)! We string players use our bow in much the same way as sculptors use their hands (or tools)
To get a succulent, rich, fat, juicy sound it can be a helpful concept to imagine that we are bowing in honey, Nutella, Nocilla or any other delicious thick liquid. Air is just not viscous (resistant) enough! But attention ! ……. some music – a lot of it in fact – doesn’t need or want this thick beefsteak sound. If we have been playing a lot in big orchestras, and/or playing a lot of Romantic and Modern music, we can very easily develop a tendency to press too hard. In that case, we need to change repertoire and play more Baroque, Early Classical (not Beethoven!), Schubert and French music!
THE PRESSURE/SPEED RATIO: THE SCRATCH AND THE CONCRETE-MIXER
Bow speed and bow pressure are normally like opposites: yin and yang, male and female, black and white, but they are intimately linked to each other. We could usefully use the concept of the P/S ratio, where “P” = bow pressure and “S” = bow speed. As this value gets higher, our sound gets thicker and denser (oil paints), whereas as it gets lower, our sound gets “airier” (watercolours). When this value becomes unbalanced, we enter into the world of special effects. Whereas “sul tasto flautando” (created by a very low pressure and high bowspeed) is a valid musical effect, the same cannot be said for what happens to the sound when the pressure side of the equation goes through the roof. This causes some very unmusical sound effects. When it happens at the start of the note, we get a scratch. And if we continue with this excess pressure (in relation to speed), then we get the concrete-mixer sound (rough and grinding). Thus the scratch and the concrete-mixer sound are the highly audible symptoms of a bow-pressure that is too high in relation to the bow speed. Or, to say the same thing from the opposite perspective, the scratch and the grind are symptoms of a bow-speed that is too slow relative to the bow-pressure. To fix this, either we speed up the bow, or relax the pressure ……. or both! As a general rule, we could say that an excess of bow-pressure is not only more dangerous but also much more common than an excess of bow-speed. This is why many excellent cellists are very cautious with their use of the word “pressure”, preferring usually to talk more about bowspeed as the source of phrasing and dynamics.
PHRASING AND DYNAMICS: PRESSURE OR SPEED?
Dynamics and phrasing are almost entirely a question of this bowspeed/pressure relationship but energy, vitality and “air” always come from bowspeed. And in fact, dynamics very often refer more to an energy level rather than a decibel level, which emphasises the importance even more of bowspeed in relation to pressure for making phrasing and dynamics. When high bowspeed and pressure combine together, we get the potent fireworks an extremely high energy ff, whereas we can make the difference between a high-energy (french) pp and a tragic deathly pp simply by varying our bow-speed with an identical pp bow-pressure: high-energy =fast bow, while tragedy = low energy = slow bow (see below).
Look at the following sequence of basic exercise ideas, in order of increasing complexity, that we can use to observe, practice and automate the complex interrelationship between Bow Pressure and the other bow variables. Play very easy things and experiment with the effect of varying the bow pressure, first on its own, then progressively adding the other variables to the mix (speed, point of contact, hair angle, left-hand distance from bridge etc). Once again, this is like an artist experimenting with mixing colours. This is our palette.
1. Vary the bow-pressure without changing any of the other variables (speed, point of contact, bowhair angle, left-hand position)
2. Vary the bow-pressure while simultaneously varying one other variable, for example:
………. left-hand distance from the bridge
……….. bow speed
……….. point of contact
3. Vary the bow pressure while simultaneously varying two other variables, for example:
………. left-hand distance from bridge AND bow speed
……… left-hand distance from bridge AND point of contact
………. bow speed AND point of contact