Rosin (), also called colophony or Greek pitch ( la, links=no, pix graeca), is a solid form of

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...

obtained from

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts ...

s and some other

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

s, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...

components. It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperature. It chiefly consists of various

resin acid Resin acid refers to mixtures of several related carboxylic acids, primarily abietic acid, found in tree resins. Nearly all resin acids have the same basic skeleton: three fused rings having the empirical formula C19H29COOH. Resin acids are tack ...

s, especially

abietic acid Abietic acid (also known as ''abietinic acid'' or ''sylvic acid'') is an organic compound that occurs widely in trees. It is the primary component of resin acid, is the primary irritant in pine wood and resin, isolated from rosin (via isomerizat ...

. The term ''colophony'' comes from , Latin for "resin from Colophon" ( grc, Κολοφωνία ῥητίνη, Kolophōnia rhētinē), an ancient Ionic city.

Properties

Rosin is

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Br ...

and

friable Friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, ...

, with a faint piny odor. It is typically a

glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling ( quenching ...

y solid, though some rosins will form

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...

s, especially when brought into solution. The practical melting point varies with different specimens, some being semi-fluid at the temperature of boiling water, others melting at 100 °C to 120 °C. It is very flammable, burning with a smoky flame, so care should be taken when melting it. It is soluble in alcohol,

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

and chloroform. Rosin consists mainly of

, and combines with caustic alkalis to form salts ( rosinates or pinates) that are known as

rosin soap Rosin (), also called colophony or Greek pitch ( la, links=no, pix graeca), is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene com ...

s. In addition to its extensive use in

soap making Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used a ...

, rosin is largely employed in making

varnishes Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in various ...

(including fine violin varnishes),

sealing wax Sealing wax is a wax material of a seal which, after melting, hardens quickly (to paper, parchment, ribbons and wire, and other material) forming a bond that is difficult to separate without noticeable tampering. Wax is used to verify something ...

and various adhesives. It is also used for preparing shoemakers'

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...

, for pitching

lager Lager () is beer which has been brewed and conditioned at low temperature. Lagers can be pale, amber, or dark. Pale lager is the most widely consumed and commercially available style of beer. The term "lager" comes from the German for "storag ...

beer

casks A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...

, and numerous other purposes such as providing backing surfaces to tin ware, copper ware, or even silver and gold vessels when embossing or engraving them. Its relatively low melting point, and firm solid form allows liquid rosin to be poured into the vessel, and when cooled allows embossing or engraving of the vessel without deforming the vessel - even if it has a skin which is quite thin. Afterwards, the object can be reheated in an oven, and the rosin poured out for reuse. Any remaining rosin film can easily be rinsed away with alcohol or other solvents. Rosin is also sometimes used as internal reinforcement for very thin skinned metal objects - things like silver, copper or tin plate candlesticks, or sculptures, where it is simply melted, poured into a hollow thin-skinned object, and left to harden. Prolonged exposure to rosin fumes released during soldering can cause

occupational asthma Occupational asthma is new onset asthma or the recurrence of previously quiescent asthma directly caused by exposure to an agent at workplace. It is an occupational lung disease and a type of work-related asthma. Agents that can induce occupationa ...

(formerly called ''colophony disease'' in this context) in sensitive individuals, although it is not known which component of the fumes causes the problem. The type of rosin used with bowed string instruments is determined by the diameter of the strings. Generally this means that the larger the instrument is, the softer the rosin should be. For instance,

double bass The double bass (), also known simply as the bass () (or by other names), is the largest and lowest-pitched bowed (or plucked) string instrument in the modern symphony orchestra (excluding unorthodox additions such as the octobass). Similar i ...

rosin is generally soft enough to be

pliable {{Short pages monitor