The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Coloring Finishing And Painting Wood
The following is a United States Navy Department (52V2a, 1914) specification for dammar-varnish:
Composition I. — To consist exclusively of a solution of pure dammarresin in petroleum spirits (turpentine snbstitnte) and to be absolutely free from all foreign matter. To contain not less than 55 per cent nor more than GO per cent by volume of petroleum spirits.
142. Mastic-Varnish.—The most important European resin, with the exception of colophony (col'o-pho-ny) or colophonium, which are other names for common rosin, is mastic, which comes largely from Chios, one of the Greek islands located in the Aegean sea. Similar resins are found in some parts of Greece, Africa, and Syria. Masticresin is the product of exudation from the lentix tree (Pistacia lentiscus), also .called the Pistacia, a Mediterranean evergreen tree. The resin is thrown out in response to wounds, which are vertical incisions in the bark, and is collected in the form of spherical or slightly flattened tears or grains. After being exuded from a wound the liquid resin gradually becomes dry and hard. In Turkey it is sometimes used as a chewing-gum, tho it has a slightly bitter taste. Its odor is, however, rather agreeable and pleasing.
Mastic-gum soon softens when placed in the mouth and crushed between the teeth; while sandarac, a somewhat similar resin, is crushed into powder. A lentix tree in good condition is said to yield as much as eight to ten pounds of mastic-resin per year, if properly cared for during the gum-producing season. The tree, which is sometimes called the lentiscus, is hardly more than a shrub, usually growing to the height of only ten or twelve feet.
Mastic-resin, when it appears on the market, is of a pale yellowish or slightly greenish color. It is a very soft resin, fusing at a temperature slightly below the boiling point of water (95° C). The gum, however, begins to soften at a temperature of about 85° C.
The active ingredient in mastic-resin is known as mastic-acid (C40H64O4).
Clastic-resin is used to a limited extent in the manufacture of a number of transparent or colorless varnishes, being completely soluble in turpentine, ether, and benzol, and largely soluble in acetone. In alcohol, about 36 per cent of insoluble matter is left as a residue. Petrol ether has only a slight solvent action on the gum.
Artists are probably the chief users of various kinds of mastic-varnish. It is often mixed in small quantities with turpentine and boiled linseed-oil and used as a vehicle in mixing with artists' oil-paints, thus giving more luster to paintings than would be produced by using either linseedoil or turpentine or a mixture of both.
