But before this has been arrived at, many busy heads have been at work in the selection of materials and in their manipulation; for in the work of ordinary painters and 'paintresses,' rapidity of execution, as well as artistic dexterity, is required in order to earn a livelihood. On an average, one penny is the price allowed for the central floral pattern of an ordinary plate--such as a pink-rose with buds and leaves, a convolvulus, or any other simple flower. Each colour must be laid on with firmness and precision; and where the light is to fall, as on the convex petal of a rose, the effect must be produced by a rapid touch of the finger removing the colour. With a convolvulus, however, it may be remarked, the colour is dashed on rapidly, and with each dash the hair-pencil is swept to a point, more or less fine, according to the style of flower; and with _blue_ flowers especially, the rule well known to watercolourists in painting an azure sky is never departed from. The bisque or unglazed ware is now but seldom embellished with painting, for colours are found to have little brilliancy on its porous surface; consequently, this kind of ware is chiefly used where _form_ alone is the paramount consideration. In the manipulation of metallic colours, the superior porcelain-painter has to calculate the ultimate effect with the same care as the fresco or destemper painter; and yet it is surprising how limited is the fame of those who decorate our drawing-room and dessert ware with their artistic work, in which a few masterly touches in birds and flowers, figures and landscapes, give life to the cold clay; for with certain exceptions these artists are not allowed even to add their initials to their work. Considerable nicety, only to be acquired by practice, is requisite in mixing the metallic colours; and for this purpose spirit of turpentine, combined with a thick oil obtained from exposure to the air for a certain length of time, of ordinary turpentine (called _fat_), is used; but should more _body_ be required, tar is added. The mixed colour is then applied to the porcelain in the same manner as in ordinary oil-painting, but with one marked and important difference, namely, that in porcelain painting the colour must never be _worked_, but must be applied with a _full_ brush, carried with a clean and precise sweep to lighter gradations of tint. Thus, the greatest depth of colour indicates the first impact of the full charged brush. Inattention to this dominating rule would be productive of clogginess and opacity.