Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/50



Mediums. These are requisites, and upon the kind used and upon their quality depends, to an extent greater than is generally supposed, the appearance of the finished work. The mediums are, as their other general name of vehicles indicates, the carriers of the paint, the means by which it may be spread. The mediums in general use and which give every satisfaction are of two kinds, a spirit and an oil, the latter being the vehicle proper, the former, the thinning agent to render practicable the spreading of the mixed oil and paint in a coat of any desired depth or thickness. The spirit and the oil are both either of turpentine or of tar, spirit and oil of turpentine being used together, and spirit and oil of tar.

Turpentine. The ordinary turpentine of the house-painter will answer the purpose, but it will be found best to procure rectified spirits of turpentine as sold by the druggist, which is as clear as the proverbial crystal, and as limpid as the purest water. The common turpentine may be used for washing brushes. The oil of turpentine is also known as fat oil. It is viscid, much of the consistency of golden syrup, and has something of the color of clouded amber. This may be purchased for a few cents a small bottle, but it may be prepared from spirits of turpentine by any one, thus: Into a flat saucer pour a little spirits of turpentine, say a tablespoonful, according to the size of the saucer, and over the saucer place a layer of muslin, sufficiently close in texture to prevent dust getting to the turpentine, and yet not so close as to prevent evaporation. The saucer with the muslin drawn tight over it should now be put in a place here evaporation will be free, but not over the fire or stove so as to hasten evaporation, or the heat might dissipate the whole. When the spirituous part of the liquid has