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1950-51 Theatre Catalog, 9th Edition, Page 414 (392)

1950-51 Theatre Catalog, 9th Edition
1950-51 Theatre Catalog
1950-51 Theatre Catalog, 9th Edition, Page 414
Page 414

1950-51 Theatre Catalog, 9th Edition, Page 414

THE EFFECT OF TIME ON PAINT. Left picture shows o: freshly dried film of SWP gloss white (magnified six times, as also are the others). The nib: shown are a few specks of pigment but mostly extraneous dirt which has fallen into the paint. Center picture is the appearance after a year's

be more conducive to increased sale of a given paint in any locality than the ocular demonstration of its value. It is this demonstration of convenience, economy and durability that has caused the consumption of prepared paint to expand to its vast proportions at the present day.

Paint Ingredients

The materials used in the manufacture of house paint are pigments or finely divided minerals, drying and semi-drying oils, volatile thinners and solvents, driers, and varnishes.

Drying oils-As used in paint, drying oils help to insure the distribution that will result in a firme coherent and adherent film of the desired luster. Unusually of vegetable origin, drying oils harden into elastic films through the absorption of oxygen, an action which can be increased by the catalytic action of driers containing salts of such metals as lead, manganese, and cobalt.

In the order of importance, drying oils are linseed oil, tung oil, and fish oil. Fish oil, properly refined, finds special service in coatings for metal surfaces subjected to heat.

Semi-drying oils are also of considerable importance, and include such items as cottonseed, hempseed, corn, dehydrated castor, and soybean oils.

Driers-Driers are added to paint to minimize the exposure time of the wet film and to permit the application of additional coats in the shortest possible time.

Driers are salts of metalsesuch as lead, manganese, and cobalt-and promote the oxidation or polymerization of the drying and semi-drying oils, They are usually salts of organic acids (rosin, naphthenic acid, and the like).

The inclusion of driers in paint by no means prolongs its life. The final destruction of good paint is primarily due to progressive oxidation and, aC<

exposure in Florida. appearance after 4; lost most of its gloss, it is clean and there are no checks or cracks. Such material is entirely satisfactory for house paint usage. (S-W photographs.)

cordingly, any material, like the driers, which hastens oxidation, shortens the life of the paint job and, therefore, the proportion of drier should be limited to its practical necessity. The percentage of drier must, accordingly, be adjusted carefully to the formula of the particular product.

Volatile Thinners include petroleum thinners (mineral spirits, VM&P naphtha, and the like), turpentine (gum turpentine, wood turpentine, and spirits of turpentine), alcohol (methyl and ethyl), benzol and allied coalstar distillates, and so forth. The form clear solutions with the oils used in paints, and completely evaporate rapidly on exposure.

Some volatile thinners are more generally used in such items as varnish removers and bronzing liquids than in paints.

Varnishes-As used in paint manufacture, varnishes are solutions of resins or fossil gums in drying oils, with added volatile thinners and dryers, or of the newer synthetic resin varnishes. Such varnishes are used chiefly as the vehicle of enamels, quick-drying floor paints, and synthetic house paints.

Types and Uses of Point

The best paint is the kind that best and longest protects and beautifies the surfaces to which it is applied.

Some of the types of paints, and their uses, are enumerated in the following paragraphs.

House Paint is paint designed to protect and beautify the surfaces of materials used in construction of buildings, especially of dwellings. Materials used in the manufacture of house paint include pigments, drying and semi-drying oils, volatile thinners and solvents, dryers, and varnishes. A properly prepared paint, applied to outside surfaces, should last from three to five years, depending on the conditions of exposure and climate.

The surface is chalking freely. Right picture is the years' exposure. While still chalking and having

Flat Wall Paint is that type of interior paint designed to produce a lusterless finish, especially on plaster, which is, by being washable, more sanitary than Wallpaper and, by being more durs able, more economical.

The vehicle is usually tung oil varnish, modified by soybean oil (because of its colorlessness) with a large volume of mineral spirits, or an alkyd.

Mill Whites are paints of the enamel type for use on interior wall surfaces to augment illumination in order to reduce hazards and promote physical comfort and reduce cost of illumination. The vehicle is usually an ester gum-tung oil varnish.

Mill whites are usually offered in three types of finish: glossy, semi-flat, and fiat. Some manufacturers furnish a limited range of colors. The paint is applied in two coats in a primer and a finish, the first'to level the surface and insure adhesion, and the second to insure reflection and diffusion of light.

Quick-Drying Paints, or enamels, are often called fifour-hour enamelsi, and so forth. The principal vehicle is usually a varnish of the alkyd type.

Quick-drying house paints are those which, hardening in a few hours, permit a second coat to be applied a very short time later. As in the "four-hour enamels}, the phenolic type resins generally play an important part as also do specially treated drying oils.

Aluminum Paint has a pigment consisting of finely divided aluminum particles in flake form suspended in a suitable vehicle, usually of the oilvarnish type. Its chief uses are in painting structural steel and interiors of industrial buildings and as priming coats for wood.

Aluminum paints, owing to the shape of the metal particles, have the unique property of leafing: the tiny flat flakes rising to the surface of the liquid and forming there a metallic layer.

1950-51 Theatre Catalog, 9th Edition, Page 414