The following are the chief Resins employed in the manufacture of Varnishes

Amber

This resin is most distinguished for durability. It is usually of some shade of yellow, transparent, hard and moderately tough. Heated in air, it fuses at about 549°; it burns with a clear flame, emitting a pleasant odor, anime.

This is imported from the East Indies. The large, transparent, pale-yellow pieces, with vitreous fracture, are best suited for varnish. Inferior qualities are employed for manufacturing gold-size or japan-black. Although superior to amber in its capacity for drying, and equal in hardness, varnish made from anime deepens in color on exposure to air, and is very liable to crack. It is, however, much used for mixing with copal varnish.

Benzoin

This is a gum-resin but little used in varnishes, on account of its costliness.

Colophony

This resin is synonymous with arcanson and rosin. When the resinous juce of Pinus Sylvestris and other varities is distilled, colophony remains in the retort. Its dark color is due to the action of the fire. Dissolved in linseed oil, or in turpentine by the aid of heat, colophony forms a brilliant, hard, but brittle varnish.

Copal

This is a gum-resin of immense importance to the varnish-maker. It consists of several minor resins of different degrees of solubility. In durability, it is only second to amber. When made into varnish, the better sorts become lighter in color by exposure to air.

Copal is generally imported in large lumps about the size of potatoes. The clearest and palest are selected for what is called body-gum; the second best forms carriage-gum; whilst the residue, freed from the many impurities with which it is associated, constitutes worst quality, fitted only for japan-black or gold-size.

In alcohol, copal is but little soluble; but it is said to become more so by reducing it to a fine powder, and exposing it to atmospheric influences for twelve months. Boiling alcohol or spirit of turpentine, when poured upon fused copal, accomplishes its complete solution, provided the solvent be not added in too large proportions at a time. The addition of camphor also promotes the solubility of copal; so likewise does oil of rosemary.

Dammara

This is a tasteless, inodorous, whitish resin, easily soluble in oils. It is not so hard as mastic, with which it forms a good admixture.

Elemi

This is a resin of a yellow color, semi-transparent, and of faint fragrance. Of the two resins which it contains, one is crystalliz-able and soluble in cold alcohol.

Lac

This constitutes the basis of spirit-varnish. The resin is soluble in strong alcohol aided by heat. Its solution in ammonia may be used as a varnish, when the articles coated with it are not exposed more than an hour or two at a time to water.

Mastic

This is a soft resin of considerable lustre. The two sorts in commerce are, in tears and the common mastic; the former is the purer of the two. It consists of two resins, one of which is soluble in dilute alcohol. With oil of turpentine, it forms a very pale varnish, of great lustre, which flows readily, and works easily. Moreover, it can be readily removed by friction with the hand; hence its use for delicate work of every description.

Turpentine

This is of very extensive use. The older it is, the more ozonized, the better it is. Turpentine varnishes dry much more readily than oil varnishes, are of a lighter color, more flexible and cheap. They are, however, neither so tough nor so durable.

Alcohol

This is employed as the solvent of sandarach and of lac. The stronger, caeteris paribus, the better.

Naphtha And Methylamed Spirit Of Wine

These are used for the cheaper varnishes. Their smell is disagreeable. The former is, however, a better solvent of resins than alcohol.