coat will depend on the manner in which it is to be finished. If it is to be painted twice in oil and flatted, the next coat should be mixed up chiefly in oil, and tinted like the finishing color to form a ground for the flatting. The greater the gloss of the ground, the more dead will be the finishing coat, or flatting; likewise, the more dead the ground the better will the finishing oil shine. It is, therefore, a general rule, that for finishing in oil the undercoat should be turpentine, and for finishing flat the undercoat or ground color should be oil; but all turpentine grounds must have a little oil mixed with them, and all oil undercoats must have a small quantity of turpentine added to them, excepting the priming or first coat in new work.
In order to attain an absolutely solid appearance, some painters apply two coats of the finishing color, by which no doubt uniformity is secured, but the expense is, of course, materially increased thereby. There are, however, pigments of a cheaper but still permanent character, which approach in tone to the very best, and these may with advantage be used as a first finishing coat, over which the final color may be applied. Such colors must be carefully selected and must be well covered by the finishing coat.
Flatting, When the work is to be flatted, that is, when it is desired that the paint when dry should present a flat or dull appearance without any gloss, the paint used for the previous coat should be rather thicker than would under other circumstances be used; it should be mixed with linseed oil and turpentine and should be rather darker than the flatting itself is to be.
Special care is necessary in laying all the coats which precede the flatting; they must be very evenly spread and must be smoothed with glass paper in order that they may be perfectly level, otherwise the smallest irregularities will appear in the finished surface, to the injury of that perfectly flat appearance in which the beauty of the work consists.
