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Adhesives, Paints, and Varnishes: Mastic

Mastic. A valuable gum resin produced from certain trees and shrubs in Barbary, the Levant, and China.

It is used as an ingredient in many varnishes. Used by itself it is transparent, brilliant, tough, and delicate. It is also often employed in finishing maps and paintings, also in medicine, dentistry, and in mounting articles for the microscope. Mastic is used with other ingredients in varnish to impart a gloss.

Rosin or Colophony. - This substance is the residue obtained by distilling crude turpentine from pine trees, of which it comprises about 70 per cent to 90 per cent. It is largely manufactured together with oil of turpentine in North Carolina. In color it ranges, according to its purity, from transparent or straw color to a brownish yellow. It can be dissolved in alcohol, ether, wood spirit, linseed oil, or turpentine, partly in petroleum but not in water. It can also be dissolved by nitric acid and alkalies. It is largely used in varnishes and cements, in calking ships, in the preparation of plaster and ointments, in soldering metals, in making yellow soaps, and otherwise. A common use is for covering the bows of violins.

Sandarac is produced from a small coniferous trce in Barbary. It occurs in pale-yellow oblong grains or tears covered with a fine dust. It is transparent and brittle. It is used in pharmacy as an incense, and in varnishes, and also in powdered form it is rubbed on writing paper where erasures have been made in order to prevent the spread of ink. It is partly soluble in cold alcohol, and wholly in alcohol brought to the boiling point.

Gums. Gums are substances which occur in plants and some animals, but which are neither oily nor resinous.

They exude for the most part from various trees when the bark is cut.