rosin

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rosin

or

colophony,

hard, brittle, translucent resinresin,
any of a class of amorphous solids or semisolids. Resins are found in nature and are chiefly of vegetable origin. They are typically light yellow to dark brown in color; tasteless; odorless or faintly aromatic; translucent or transparent; brittle, fracturing like glass;
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, obtained as a solid residue from crude turpentineturpentine,
yellow to brown semifluid oleoresin exuded from the sapwood of pines, firs, and other conifers. It is made up of two principal components, an essential oil and a type of resin that is called rosin.
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. Usually pale yellow or amber, its color may vary from brownish-black to transparent depending on the nature of the source of the crude turpentine. Rosin has no taste but often has a faint odor of pine. It is soluble in alcohol, ether, turpentine, and several other organic solvents, and in solutions of various metal hydroxides. Rosin is not a pure substance but a mixture of several compounds, chiefly abietic acid. It is used in making cements, varnishes, paints, sealing wax, adhesives, and some soaps; for treating violin bows; as a dressing for machine belting; as a sizing material for paper; in the preparation of certain metals for soldering; and, in pharmacy, in some ointments, plasters, and similar preparations. Athletes commonly rub it (in the form of dust) upon their hands or the soles of their shoes to prevent slipping.

Rosin

 

(or colophony), a brittle, vitreous substance varying in color from light yellow to dark red; one of the resinous substances found in pine trees and obtained in the form of residue following distillation of the volatile part from these substances. Rosin has a density of 1.07-1.085 g/cm3 and a softening point of 52°-70°C. A poor conductor of heat and electricity, it dissolves readily in ether and alcohol but is insoluble in water. It is composed of resin acids (80-95 percent) of the general formula C19H29COOH and of neutral unsaponifiable substances (5-12 percent).

Rosin is classified according to the type of raw material and to the method of preparation as follows: gum rosin (obtained by distillation of turpentine oil from refined turpentine), wood rosin (obtained by extraction of wood chips from tarred pine stumps using organic solvents, primarily gasoline), and tall oil rosin (obtained by fractional distillation of crude tall oil, a product of sulfate soap refining). Rosin and its derivatives are used in sizing paper and cardboard; as emulsifiers in the manufacture of synthetic rubbers, elastics, plastics, artificial leathers, linoleums, soap, varnishes, paints, and electrical insulating mastics and compounds; and as a flux in the tinning and soldering of metals.

REFERENCES

Vasechkin, V. S. Tekhnologiia ekstraktivnykh veshchestv dereva. Moscow-Leningrad, 1953.
Komshilov, N. F. KanifoV, ee sostav i stroenie smolianykh kislot. Mos-cow, 1965.

P. P. POLIAKOV

rosin

[′räz·ən]
(materials)
A translucent yellow, umber, or reddish resinous residue from the distillation of crude turpentine from the sap of pine trees (gum rosin) or from an extract of the stumps and other parts of the tree (wood rosin); used in varnishes, lacquers, printing inks, adhesives, and soldering fluxes, in medical ointments, and as a preservative.

rosin, colophony

A resin obtained as a residue in the distillation of crude turpentine from the sap of pine trees (gum rosin) or from an extract of the stumps and other parts of them (wood rosin).

rosin

a translucent brittle amber substance produced in the distillation of crude turpentine oleoresin and used esp in making varnishes, printing inks, and sealing waxes and for treating the bows of stringed instruments