# Rosin

Source: https://arcosounds.com/glossary/rosin
Also known as: colophony

**Rosin is the hardened tree resin applied to bow hair to create the friction that makes a string speak; without it the bow slides silently across the string.**

Bow hair alone is too smooth to grip. Rosin makes the hair catch and release the string hundreds of times a second, the stick-slip mechanism that actually produces the sound. Dark rosin is softer and grippier, suiting cello and bass and cooler, drier climates; light rosin is harder and cleaner, suiting violin and viola and humid conditions. Bass rosin is markedly stickier than the rest.

A few strokes before playing is enough for a maintained bow. Over-rosining produces a gritty tone and a visible cloud of dust on the instrument, and the residue should be wiped off the strings and the top after every session, since it hardens and eventually damages varnish.

Canonical source: https://arcosounds.com/glossary/rosin