(6) 20 parts prepared purple, 10 blue, 5 1/2 enamel flux (2), ] white enamel.
20 parts prepared rose colour, 1 white enamel. The purples and rose colours for glass painting are nearly the same mixtures as those used for porcelain painting, with the addition of a small proportion of flux and white enamel. The latter gives firmness to the colour. In the course of working the rose colour, if a very small quantity of purple be added, the colour will be perceptibly benefited.
1 part terra de sienna, 3 enamel flux (2). The terra de sienna must be calcined over a slow fire until its colour becomes of a dark red, after which it is washed several times in boiling water and ground with the flux for use.
1 part oxide of silver, 10 enamel flux (2), 10 enamel flux (3), 1 white enamel.
1 part highly calcined copperas, 3 1/2 enamel flux (3).
1 part easy calcined umber, 3 1/2 enamel flux (2).
(a) 5 parts cornelian red, 1 prepared purple.
(6) 2 parts blue, 1 yellow.
(6) 4 parts borax, 4 1/2 flint glass, 1 flint, 1/2 potash, 1/2 prepared purple, 1 blue calx.
In preparing these blues, let the materials be calcined in an air furnace, and the whole mass kept in a state of fusion for some time, a fine blue glass enamel will be produced. The cobalt blue calx should be of the finest quality that possibly can be procured, and free from all impurities.
(a) 1 part highly calcined umber, 2 calcined borax, 1 red lead, 1 blue calx.
(6) 1 part manganese, 1 black flux.
The best Turkey umber should be procured for the first process, and calcined at the most intense heat that can be produced in an air furnace, after which pound and mix up with the other materials; then calcine the whole together in an air furnace. The degree of heat will be sufficient when the whole mass is in fusion.
1 part precipitate of gold, 4 1/2 enamel flux (4), 1/6 white enamel. These ingredients are simply ground together for use. They produce a beautiful colour on glass, of a fine purple hue. This very expensive colour is adapted principally for painting the draperies of figures, and is very susceptible of being injured by a high degree of heat.
(a) 7 parts red lead, 2 calcined borax, 2 flint, 1 oxide of tin.
(6) 8 parts red-lead, 6 flint glass, 3 flint, 1/2 green copperas.
The materials of the last two processes must be finely mixed and calcined in an air furnace, each process separately, after which take 2 parts of (a) and 3 parts of (6), mix them together, and repeat the calcination again in an air furnace; then pound and grind this frit for use, but be particular that it is ground very fine, for much depends on the particles being minutely mixed previous to using. The composition is afterwards laid on the glass with water, and a small quantity of refined sugar dissolved in spring water is applied occasionally; the solution of sugar must be of the consistence of thick oil; should too large a quantity of the solution be added, and by that means condensate it too much, add a few drops of acetous acid to the menstruum; it will immediately regain a proper consistence, and not at all injure the colour. When the deadening is laid on the glass, the figures must be engraved or etched with a pointed instrument made of wood) bone, or ivory, suitable to the subject, and afterwards burnt in a kiln or muffle appropriated for the purpose.
It fires at a less temperature than stained glass, although in some instances it will do in the same kiln. (See also iii. 228.)
132 tainting: oil colours.
Palettes are made of mahogany, and of satin and other light-coloured woods also; those made of the latter are preferable, because the colours and mixed tints are best seen upon them. They should be light in weight, and thin, and so perforated as to rest well-balanced on the thumb. Palettes are made of oval and oblong shapes; the latter form is more generally useful and convenient, as affording a greater space for the working of tints, as well as for their advantageous arrangement. Wooden palettes should be prepared for use by rubbing into them as much raw linseed oil as they can be made to imbibe. If this dressing with oil be thoroughly effected, and the palette be then suffered to dry till it becomes hard, the wood will subsequently not be stained by the absorption of colour. A palette thus prepared is easily cleaned, and presents a hard and polished surface, exceedingly agreeable for the preparation of tints. It is important to keep the palette free from indentations and scratches, and on no account to neglect cleaning it; the colour never being allowed to harden upon the wood.
The easel is a frame which supports the painting during its progress. Easels are of various forms; but the most convenient is undoubtedly the rack-easel, which allows the painter to raise or lower his work with speed and convenience, as occasion may require. The commoner and cheaper kinds are supplied with pegs for this adjustment of the height of the work. It is desirable that the easel should stand firmly, and not be liable, as is too often the case, to be overset by any slight cause.
This is used to rest or guide the right hand or arm when particular steadiness is required, as is the case in the painting of small objects and minute details. It is usually formed of cane or of lance-wood, and it should be light, yet firm. The lower end of the stick is held in the left hand, while the upper extremity, which is covered with a soft round ball or pad of leather, to prevent injury, rests on the canvas or some other convenient support.