Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/269

Rh agglutinated. The inexperienced workman thinks the color is well mixed, because he has, during mixing, lost sight of the particles of color, but when he comes to spread the wash on the wall, the dark specks emerge from their temporary cases, and, as they are dragged along by the brush, cause lines and streaks of more or less breadth, according to the number of particles which have been bound together. These may not perhaps be noticed whilst the color is wet, but will son appear as it dries, and the evil result will not be in appearance only, for as these specks of color have not been bound by the size with which the whole mass has been mixed, the spots and streaks caused by them will rub off, leaving the original color of the plaster, or of the previous wash, visible. Sometimes, too, when the powder color is of a heavier character than the mass, it finds its way to the bottom of the bucket or pot, and when the quantity is nearly used, the last part of it will be found to become gradually darker than that previously used, whilst if the brush be allowed to touch the bottom, it will bring up a quantity of dark color which will be deposited with the first stroke on the wall.

Great care must be taken in mixing tints, for some colors, such as Prussian blue, are so strong that a very little of them will produce the desired effect, and thus, if they are used without consideration, it becomes necessary to add more and more white, a greater quantity of the tint required is compounded, and waste results. The safer plan is to mix a small quantity of the tint in a jar or on a piece of glass, and, having spread this on a piece of paper, the painter will be able, when it is dry, to judge of the shade, and to form an idea as to the relative qualities of the different colors required. Other colors again, such as orange lead, are of such density, that they will separate from the others and sink to the bottom, and therefore tints compounded with these must be worked in a size jelly, this, too, will be learnt by trial and experience.