MANUFACTURE. —The composition of the different kinds of varnish may now be considered. Then. classification is as fullows :— Div. I.—Natural varnishes, of the Chinese, Japanese, and Indian types, containing no fixed fatty oils nor any volatile ingredients, hut drying by oxidation at ordinary temperaturss, and without any preparation by heat, driers, or otherwise (see p. 1692).
Div. II.—Fatty drying oils, which harden and resinify by oxidation in the air :— Class A.—Fat oils drying at ordinary temperatures.
Section a, in their natural state.
„ 0, which have had their natural affinity for oxygen increased by chemical or other means, but without heat.
„ 7, boiled oils, which have been rendered more drying by heating, either with or without chemicals.
Class oils, dried in a heated atmosphere (stoved), japans and enamels, oiled silk, &c.
Section a, raw oils, alone or coloured only with pigments.
„ boiled oils, alone or with pigments.
„ 7, oils combined with resins, amber, and asphaltum, and oil-varnishes of Div. III.
Class C.—Fat oils hardened by sulphuration at high temperatures ("vulcanized oils").
Div. III.—Oil-varnishes proper.—Varnishes containing as fixed residue a drying fat oil com bined with resin, either with or without a volatile solvent or diluent, and in which the quantity of oil is greater than—or at least equal to—that of the resin.
Class A.—Oil-varuishes of the ancient type, containing no volatile diluent.
Class B.—Oil-varnishes of the modern type, thinned with a volatile solvent, but not drying hard on the evaporation of this solvent, until the drying oil in the fixed residue has become oxidized in the air.
Section a, in which the oil and the resiu have been boiled together at a high temperature. ,, 0, in which the mixture of oil and resin has been effected by solution or melting together at a low temperature.
Class C.—Black varnishes, and black japan drying at ordinary temperatures.
Div. IV.—Varnishes consisting chiefly of a resin, gum, or other solid substance, dissolved in a volatile liquid, and drying quite hard on the evaporation of the solvent.
Class A.—Dissolved in hydrocarbons, alcohols, &c., boiling above 100° (212° F.)—" essence," "essential-oil," or " oleo-resinous " varnishes.
Section a, toughened with a drying oil, in less quantity than the contained resin.
„ /3, containing no fat oil.
Class B.—Dissolved in hydrocarbons, alcohols, ethers, Sre., boiling below 100° (212° F.). Section a, spirit-varnishes made with methyl-, ethyl-, or propyl-alcohols.
„ 0, varnishes made with acetone, ethers, chloroform, &c.
„ 7, varnishes having as solvent a hydrocarbon such as benzol, petroleum, Ste. Class C.—Varnishes in which the solvent is a mixture of alcohols, ethers, Sm., with various hydrocarbons (" mixed-solvent " varnishes).
Class D.—Water-varnishes.
Div. V.—Varnishes applied by heat or friction.
Claes A.—Etching-ground.
Class B.—Heel-balls, furniture-creams, &c.