Manufacturer and builder 5, 1869
The use of frescoes, hard polished woods, or elaborately colored and tinted papers, for internal decorations is likely soon to give place, in part at least, to a recent discovery, by means of which, marble, the coarsest as well as the finest, can be colored in every variety of shade. The coloring of marble was long placed among the "Lost Arts," but it is a generally received opinion that the richly colored marbles found occasionally among the works of the ancients are not the productions of art, but of nature, the quarries of which are lost to us. The claims set forth in recent times for the production of colored marbles have always turned out to be for mere surface coloring, which in a short time and with but slight friction wore off. Some colored marbles exist in a natural state, but their rarity makes them very expensive, and they are seldom or never used, except for fine mantels in the residences of the opulent, or for ornamental vases and articles of similar kind. The naturally colored marbles are the Sienna, an Italian marble of a uniform yellow, or rather we should say a buff color, though it is at times found beautifully clouded and veined; the Lisbon, a Portuguese marble, of a delicate flesh color rarely approaching to the deepness of pink; it is found also of a dove color, varying from that to slate. In the Pyrenees is found a very fine marble of dull or brick red; the so-called Egyptian marble, which in reality comes from Italy, is found black, sometimes veined with gold. In addition to these are the Brocatelle, a Spanish marble, and our own Tennessee colored marbles. These marbles, though well known to us, are so costly as to be far beyond the reach of any but the most wealthy. An objection may be found to them in the fact that they are never obtained in large blocks, the consequence of which is, that mantels made of Sienna, or other of the finest and rarest marbles, are built of pieces of uncertain and irregular size and shape, the joints of which, however well cemented, will, in course of time, show, and detract greatly from their beauty.
The method of coloring marbles already referred to, gives us not only perfect imitations of the naturally colored marbles, but others of every conceivable tint or shade of blue, green, orange, purple, ruby, or, indeed, any color desired, while it brings out many beauties of the marble not observable in it in the natural state. The objection to the hitherto so-called colored marbles does not exist in the stone colored by this process, as the coloring matter permeates the whole mass, color-ing it completely through. The process consists simply in placing the slab in a shallow bath, the liquid being drawn by capillary attraction into the marble so as to thoroughly permeate it. The slab, if broken, will show in its inner parts the same degree and intensity of color as at its surface. The marble thus colored not only retains its color, but that color is deepened and intensified by time. It can be colored in the rough or in the polished slab, and in the former can be highly polished, while in the latter the polish can be improved upon. In the process of coloring, the interstices between the molecules of the marble are filled by the coloring matter, rendering the substance harder, more durable, more impervious to damp, an capable of higher and better finish, while the color, not being superficial, is permanent. These considerations are sufficient to show that the colored marbles, produced by the new method, will be of great value in architectural decorations, either internal or external, as specimens have been exposed upward of two years to all the variations of climate and weather, which shows that time improves the colors instead of injuring them.