Technical data
| Instrument | cello |
| Version | No. 2 |
| Item number | HL-2063 |
Features
- Rosin for cello
- No. 2 version
In practice
- Apply sparingly. Players who re-rosin every session almost always use too much; for most, a few strokes every four to five playing hours is enough.
- A new cake often gives no deposit at first. That is not a fault: score the smooth cast surface lightly once and the bow will pick up rosin normally.
Sound and physics
Rosin (the residue left when turpentine is distilled from conifer resin) raises the static friction (the friction between two surfaces that are not yet sliding against each other) on the bow hair. The bow therefore carries the string along until the string's restoring force prevails; the string then slides back and grips once more.
The difference between static and sliding friction, to which rosin contributes, helps set the minimum and maximum bow force (the pressure of the bow on the string) between which a steady note forms. Within this range the string breaks away exactly once per vibration (Helmholtz motion), and the tone contains the complete series of harmonics (the whole-number multiples of the fundamental).
Frequently asked questions
Why does a bow need rosin?
Rosin raises the static friction between bow hair and string. The bow only carries the string for as long as that friction exceeds the string's restoring force, and the bowed tone grows from this alternation of gripping and sliding.
Where does the name colophony come from?
From the city of Colophon in Asia Minor. Colophony, or rosin, is the residue from distilling turpentine out of conifer resin.
