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Rosin is the resinous constituent of the oleoresin exuded by various species of pine, known in commerce as crude turpentine. The separation of the oleoresin into the essential oil (spirit of turpentine, containing the volatile liquid terpenes component) and common rosin is accomplished by distillation in large copper stills.

The essential oil is carried off at a temperature of between 100° to 160 °C, leaving fluid rosin, which is run off through a tap at the bottom of the still, and purified by passing through straining wadding. Rosin will vary in color, according to the age of the tree from which the turpentine is drawn and the degree of heat applied in distillation, from an opaque, almost pitch-black substance through grades of brown and yellow to an almost perfectly transparent colorless glassy mass. At room temperature, rosin is brittle, but it melts at stovetop temperature.

Chemically, it mainly consists of a mixture of organic acids known as diterpenes, of the general molecular formula C₂₀H₃₀O₂. These resin acids are isomers. The proportion of the different resin acids in the rosin is variable according to the kind of pine from which the rosin was obtained.

In fine arts, gum rosin is used in many varnishes recipes, tempera emulsions and painting-medium component for oil paintings. It is soluble in turpentine and turpentine substitute. In the printmaking technique known as aquatint, rosin is applied onto the etching plate in order to create surfaces in gray tones.

Rosin is also used for its friction-increasing capacities; for example players of bowed string instruments rub cakes of rosin on their bow hair so it can grip the strings and make them speak, or vibrate clearly. Ballet, flamenco, and Irish dancers are known to rub the tips and heels of their shoes in powdered rosin to reduce slippage on clean wooden dance floors or competition/performance stages. It was at one time used in the same way in fencing and is still used as such by boxers.

In addition, rosin is largely employed in making varnishes (including fine violin varnishes), sealing wax, in soap making and various adhesives. Rosin is also an ingredient in preparing shoemakers' wax and for pitching lager beer casks, in printing inks, photocopying and laser printing paper, varnishes, adhesives (glues), paper sizing, soda, and soldering fluxes.

identification

• CAS: 8050-09-7
• EINECS: 232-475-7
• appearance: powder or crystal fragments, pale yellow to amber
• synonyms: Greek pitch, colophony,

physical properties

• melting point: 90 to 110 °C (softens)
• solubility: turpentine, d-Limonene, alcohol, ether, benzene and chloroform
• density: 1.07 to 1.09 g/cm³
• self-ignition T°: 340 ° C
• flash point: 180 ° C

All values given in the International System of Units (SI), unless otherwise noted.

safety data sheets

All the information above is, to the best of our knowledge, considered to be exact and does not constitute a product specification or warranty. Materials should always be thoroughly tested prior to selecting them for definitive use.