rosin

Rosin, also known as colophony, is a solid form of resin derived mainly from pines and other conifers. It is produced by heating fresh resin obtained from tapped trees to evaporate volatile components such as turpentine, leaving a brittle, translucent solid that ranges in color from pale amber to brown.

Rosin is obtained from the natural exudate of pine species (principally Pinus) and related conifers worldwide. After resin collection, the liquid fraction is evaporated and the remaining solid is processed into blocks or pellets for sale. The material consists largely of rosin acids (diterpenoid acids such as abietic and dehydroabietic acids) along with neutral resins and hydrocarbons. The properties vary with source and refining, producing hard rosin or soft rosin, depending on how much of the volatile fraction is removed and the heat treatment.

Common uses include music, where rosin is applied to the bows of violin, viola, cello, and bass to increase friction with the strings and produce sound; in soldering and electronics, rosin flux cleans and facilitates solder adhesion on metal surfaces; in varnishes, adhesives, and polishes, rosin acts as a tackifier and binder; and in paper and chemical industries, rosin acids are used in sizing agents and in the production of certain synthetic resins.

Safety: Exposure to rosin dust can irritate skin, eyes, and the respiratory tract; handle with appropriate ventilation and protective equipment.