The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Coloring Finishing And Painting Wood
House-painters and wood-finishers usually obtain the various hues desired from oil-ground colors, while signpainters, wagon-, carriage-, and automobile-painters commonly select colors ground in japan for their work. Grinding-japan is a very quick-drying varnish, which is made from some resin such as shellac or rosin, a linseed-oil vehicle, and a solvent together with metallic oxides which are known as driers. Such japans are thinned when necessary with a very quick-drying liquid, turpentine being the most satisfactory.
A lacquer which contains a white pigment that will produce obscuration of the surface can be colored by the use of various coal-tar dyes soluble in alcohol. While spiritsoluble dyes which are liable to fade in sunlight are sometimes incorporated into a transparent lacquer, pigmentcolors ground in japan are the materials most satisfactory for a practical finisher to add to lacquer enamels. Good results can undoubtedly be secured by adding japan-ground colors to a lacquer-thinner, and then incorporating this pigmented mixture into a clear lacquer. This method is suggested by one manufacturer, but the novice is more apt to secure good results by purchasing ready-prepared pigmented lacquers and mixing together colors of the same brand only.19
Pigments may be incorporated into lacquers during the manufacturing process by several quite different processes. If castor-oil or some other specially prepared oil is used as a plasticizer, the oil and the colors may be ground together and added to the lacquer-mixture. Sometimes the pigments are rolled into a heavy plastic mass of nitrocellulose containing a portion of its solvents. More of the solvents are added to the colored or pigmented nitrocellulose mixture after the heavy steel rollers have thoroly amalgamated the pigments and nitrocellulose into a very homogeneous mass. The other lacquer ingredients, such as the resins in solutions, plasticizers, and diluents, are thus compounded with the pigmented nitro-cotton mixture.
Other methods are also used by manufacturers, some of whom grind the pigments with certain amounts of completely compounded clear lacquer, the grinding being done in pebble mills. Another plan is to grind the pigments with some of the lacquer-reducers, and add this mixture to heavy clear lacquer. In general, it is wise to let the factory expert mix the pigments into lacquers, because he has the proper skill, knowledge, and equipment for such work. The danger from the use of colors ground in japan comes from linseed-oil which is ordinarily found in most japans. Linseed-oil does not usually react well in lacquers, tho it is sometimes used in small quantities.
Pigments are of great value in lacquers in addition to their coloring function; and, because of their presence in lacquer-enamels, these finishes can be used outdoors successfully on automobiles, particularly. Clear or transparent lacquers, however, do not wear well when exposed to bright sunlight. The pigments in lacquer-enamels seem to absorb the ultra-violet rays, and prevent their destructive action, which seems to be a decomposition of the nitrocellulose component of the film.
