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1950-51 Theatre Catalog, 9th Edition, Page 419 (397)

1950-51 Theatre Catalog, 9th Edition
1950-51 Theatre Catalog
1950-51 Theatre Catalog, 9th Edition, Page 419
Page 419

1950-51 Theatre Catalog, 9th Edition, Page 419

This rapid inroad of the synthetics on the other hand has stimulated technical research by those interested in the older materials, with the result that the surveyors of these have been compelled to improve and standardize them for use in more forms: and, as a consequence, these old kauris, congos, manillas, and so forth are rapidly resuming their ancient popularity. Furthermore, the technical men have been busy with the oils used by the industry, with the result that these are now available with practically any required property.

And the end is not yet in sight. Competition is enforcing constant progress, and though we cannot predict whither, we can safely say its path is consistently onward and upward.


Varnish, broadly speaking, is a solution of resins in liquids which, spread on a surface in a thin film, dries by the evaporation of the volatile constituents, by the oxidation or chemical reaction of other constituents, or by a combination of both processes, and leaves a continuous, protective coating,

Vegetable oils (especially the so-called drying oils), fossil gum resins, synthetic resins, natural gum resins, volatile mineral oils, thinners, metallic salts, and, to a minor extent, animal oils are the materials of varnish manufacture.

The purpose of varnish is to enhance the beauty of surfaces, to protect them from injury, to increase the luster or hardness of other coatings, and, in its technical applications, to exclude moisture and gases, vapors, and other agencies of decomposition or decay, to prevent corrosion, and to reduce friction.

The transparent and translucent forms of varnish are clearly differentiated, but some of the opaque forms are distinguished from paint only by their composition, the varnish,with few exceptions, containing resins as essential constituents.

The luster of varnish is largely due to resins. The most lustrous varnishes are sometimes soft and not durable, unless the varnish is subjected to chemical treatment or fiuxed at high temperatures with the proper oils. But such treatment involves some diminution of luster. Rosin, however, is a highly important constituent of many synthetic resins.

Elasticity of varnish is chiefly due to the constituent oils and their proper treatment, though certain resins assist this property.

The durability of varnish is due to the selection of ingredients and to the treatments of the materials, especially those involving heat. The qualities of a varnish can be determined by standard physical tests prescribed by various scientific organizations, all of which work in collaboration. The tests of the American Society for Testing Materials are in general use.

Kinds of Varnish

The varieties of varnish are almost as numerous as the branches of art and industry, each varnish-consuming art and industry requiring numerous kinds and qualities of varnish. Each of the larger manufacturers regularly lists from 100 to 200 varieties, while the special varnishes prepared for different manufacturing uses far outenumber these.

If the varnish selected for any purpose is found to be unsatisfactory, the only


OLD AND NEW INGREDIENTS. Here is (1 comparison of the durability of an old-type varnish made with natural resins and a modem spur varnish made from synthetic resins. After an exposure of nine months to weather in Florida. the old-type finish, at the left, has completely failed, while the new type. at the right. shows virtually no deterioration under the same conditions. (Sherwin-Williams photo.)

safe course is to select another varnish. All varnishes are intended to be usedand should be used*exactly as supplied by the manufacturer.

Varnishes cannot be safely mixed, reduced, or thinned. Varnish is a product of chemical reaction at high temperatures. Mixtures of two varnishes, or the addition of thinners in the cold, may induce separations and precipitations, and will certainly affect the quality.

Varnishes may be broadly classified as oil varnishes and spirit varnishes.

Oil Varnishes are substantially solutions, effected by heat, of natural or synthetic resins in a fixed oil (commonly a vegetable oil) with a small proportion of metallic salts to facilitate drying, and sudicient volatile liquid to obtain the required fiuidity.

Oil varnishes, enamels, painters' japans, and spirit varnishes (shellac and dammar varnishes) are used in the finishing of buildings.

Spirit Varnishes are substantially solutions of resins in volatile liquids. The most important of this group is shellac varnish, which is a solution of shellac in ethyl alcohol. Shellac itself is an exudation deposited by the female Loccz'fer lacca on the smaller branches of the trees of the fig family in India and neighboring countries. Such varnish dries to a hard, semi-lustrous coating.

Another less important item in the spirit-varnish class is dammar varnish, a solution of gum dammar (obtained from the sap of Shorea wilsne/ri in the Philippines and East Indies) in turpentine or mineral spirits. The whitest and best grade is known as Batavian dammar. Its chief uses are as a colorless component of lacquers; though, when dissolved in turpentine, it produces a colorless but rather soft film.

JapansuThe term, japan, includes two distinct classes of product; painters, japan and decorative japans.

Paintersy japan is a resinate drier.

Enamels-As commonly understood, an enamel is a special paint made with a varnish vehicle instead of oil, spirit, or oleoresins. The term, enamel, is very broadly and loosely applied, comprising at one extreme what are designated as "air-drying japansiy and, at the other, What might be better described as varnish-paints.

Enamels are air-drying or baking coatings, to which color and opacity have been imparted by the addition of pigments and, in some instances, dyes. They may have high or medium luster, or no luster at all.

Gloss oil, a solution of rosin in benzine, with or without a small percentage of drying oil, is used chiefly for imparting a temporary finish to unimportant articles, such as barrels.

Long oil and short oil are terms referring to the relative proportions of oils to resins. A long-oil varnish is generally slow drying, tougher, and more elastic than a short-oil varnish. Oil length is measured by oil in gallons to the hundredweight of resin.

Clear varnish is a transparent varnish, containing no pigment. Varnishes containing pigments are known as pigmented varnishes.

Flat varnishes designed to produce a matt (lusterless) finish, are special products of varied and often complex composition. The flatting may be produced by including one of the waxes or stearates, of which the most commonly used is zinc stearate. In flat mixing varnishing the percentage of volatile thinner to oil is materially increased. This type of varnish is largely used in
1950-51 Theatre Catalog, 9th Edition, Page 419