This section is from the book "A Treatise On Architecture And Building Construction Vol4: Plumbing And Gas-Fitting, Heating And Ventilation, Painting And Decorating, Estimating And Calculating Quantities", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
White Veined Marble. The ground for this marble is white, laid very smooth; the first vein will, on inspection, be found very faint; it is the broad-vein mica, seen through a great depth of the semitransparent body of the white. The shadows of white always partaking of a yellow hue, the faint vein will appear of a reddish gray, formed by mixing white, black, and Indian red to a proper tint. This must be scumbled or spread very thinly in the forms intended for the veins to take. In relation to the formation of marbles, it must be here observed, that in ore beds of rock, veined by metallic or other substances crossing them, the veins always run in the direction of the strata, precisely as thin streams of water, if poured upon an inclined plane, such as the cover of a table slightly raised on one side. If this experiment is tried, it will be found that the seams, if commencing regularly, will, from some irregularities of the surface, soon alter their course and turn in various directions, sometimes joining together, forming a sort of star, then spreading into finer threads. Others, again, join and form a thick vein, but still running in varying lines towards the bottom. This is precisely the way in which various substances spread themselves on limestone, penetrating, of course, the surface and interspersing with the strata. From this experiment, the painter will see that, however he may vary the direction of the veins, they must all appear traveling to the same point, by different roads. Nothing can be more contrary to nature than those violent and eccentric breaks into which painters of veined marbles are often led. This applies to all marbles, except porphyry, black and gold, and Florentine.
The first broad vein of the marble having been rather faintly painted, the veins near the surface are next put in. They are made a little darker by the addition of black, and drawn very thin, taking the direction of the broad, faint vein, and divided as studies from nature dictate. The veins nearest the surface must, of course, be darker than the others; the color darkened and warmed by the still further addition of black, with a little lake and blue. This vein should be drawn very thin, with a fine sable pencil, and made to take almost the direction of the last veining. Though very little veining is required, this little must be put in with spirit and skill, thereby enhancing greatly the beauty of the work. The whole of these veins are put on, one upon the other, while wet, then blended with the badger softener; when quite dry, the dark vein may be retouched, wholly or in part.
Florentine Marble. The ground for this marble is white, with Indian red and black mixed together to form a very light reddish neutral tint. The veins are umber or burnt sienna, laid on irregularly while the ground is wet; sometimes they are very close together, and then seem to break suddenly and irregularly-an effect which must be studied from natural specimens in order to be successfully imitated by hand.