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Second Part.

THE ART OF MARBLE WORKING IN GENERAL.

SECTION FIRST.

CUTTING, WORKING, AND POLISHING MARBLE.

57. The Art of the Marble worker consists in cutting, working, and polishing Marbles for the sculpture of chimney-pieces, facings, columns, pedestals, vases, basins, spandrels, rose-work, urns and monuments.

Marble workers are also commissioned with Marble pavements for compartments, stairways, vestibules, dining-rooms, baths, temples, chapels, and churches. A principal branch of their art is the sculpture of tombs and monuments; and in connection with this, they are required to engrave inscriptions upon Marble or stone, sometimes in black or white, sometimes in gold or silver. We will speak hereafter on this point.

Marbles are generally cut up in the same direction in which they are quarried; this is called sawing with the grain. Sometimes, however, it is necessary to cut them in a contrary direction; this is to saw against the grain. This renders them more difficult to work. Some marbles can only be sawed in the direction in which they are cut up.

The Marble worker is often obliged to rough hew, boast with the puncheon, and work, without the help of the saw, casings, rounded consoles, columns, and other articles with curved contours; sometimes, too, but rarely, he re-works, with the chisel, badly executed sawings; he then squares each piece with the saw or chisel, to give it the required dimensions, and finally mounts the Marble upon its stone core, and sets up his work in its place, which is not the least delicate part of the process.

The work of mouldings in particular, demands much time and pains; the first operation is to saw the arris, then to boast with a notched chisel, making several successive groovings, on account of the contour and expansion, in which but very few pieces of the material are taken, for fear of splintering it; and finally finish with small common chisels, which should be sharp and well tempered.

Cylindrical pieces, such as round pedestals, columns, urns, vases, etc., are boasted with the chisel, and then, if portable, finished on a turning lathe, by placing them between the points of large puppets, and giving them a continued rotary motion by means of a wheel, which is moved by a man in ordinary workshops, and by water or steam in large establishments. When it is impossible to place the pieces in a lathe, they are thickly grooved, boasted with puncheon, and the desired contours obtained by means of thick panels; they are then worked with a small chisel, which removes the dust, and thus prepares the Marbles for polishing.

58. A complete polishing includes five distinct operations, namely:

Grinding, which consists in smoothing the roughness left by the burin. This is done by rubbing the Marble with a piece of moist sandstone for mouldings, either wooden or iron mullars are used, crushed and wet sandstones, or sand, more or less fine according to the degree of polish required, being thrown under them.

The second process is continued rubbing with pieces of faience, without enamel, which have been baked but once, also wet.

If a brilliant polish is desired, Gothland stone instead of faience is used, and potter's clay or fuller's earth, a sort of clay mixed with fine sand, is placed beneath the mullar.

This operation is performed upon granites and porphyries with emery and a lead mullar, the upper part of which is incrusted with the mixture until reduced by friction to clay or an impalpable powder.

59. Perfection of polish depends almost entirely on the care bestowed upon these two operations, which should be performed with a regular movement, requiring much patience.

When the Marble has received this first polish, the flaws, cavities, and soft spots are sought out, and filled with mastic of a suitable color. This mastic is usually composed of a mixture of yellow wax, resin, and Burgundy pitch, mixed with a little sulphur and plaster passed through a fine sieve, which gives it the consistency of a thick paste; to color this paste to a tone analogous to the ground, tints or natural cement of the material upon which it is placed, lamp black and rouge, and a little of the prevailing color of the material, are added. For green or red Marbles, this mastic is sometimes made of gum-lac, mixed with Spanish sealing-wax of the color of the Marble; it is applied hot with pincers, and these parts are polished with the rest. Sometimes crushed fragments of the Marble worked are introduced into this cement, but for fine marbles, the same colors are employed which are used in painting, and which will produce the same tone as the ground; the gum-lac is added to give it body and brilliancy.

The third operation of polishing consists of rubbing it again with a hard pumice stone, under which water is constantly poured, unmixed with sand or other mordant.

60. For the fourth process, which Marble workers call softening the ground, lead filings are mixed with the emery mud produced by polishing of mirrors or the working of precious stones, and the Marble is rubbed with a compact linen cushion, well saturated with this mixture; the English rouge is also used for this first polish. For some outside works, and for hearths, paving tiles, etc., Marble workers confine themselves to this polish.

When the Marbles have holes or grains, as do certain Breccias, a lead mullar is substituted for this close linen cushion.

Finally, in order to give a perfect brilliancy to the polish, the gloss is applied. This is done by first washing well the prepared surfaces, and leaving them until perfectly dry; then take, again, a linen cushion, moistened only with water, and a little powder of calcined tin of the first quality. After rubbing with this for some time, take another cushion of dry rags, rub with it lightly, taking care to brush away any foreign substance which might crease the Marble, and a perfect polish will be obtained.

61. It is necessary to observe that, in order to gain time and facilitate labor, many Marble workers mix alum in the water which they use. This mordant penetrates the pores of the Marble, and really gives it a speedier polish. This, however, is a fictitious polish, which spots very easily, and which is soon tarnished and destroyed by dampness. It is necessary when purchasing mantels, tables, or other articles of polished marbles, to subject them to the test of water; if there is too much alum, the Marble absorbs the liquid, and a whitish spot is left. When Marble refuses this test, one may be sure that the polish has been forced with alum, and, consequently, will not be durable; it is very common on selling a piece of furniture of this Marble, to pronounce it a capital polish; but this is a fraud to conceal that of the artisan.

Marble workers mount and fasten their works upon plaster mixed with a third part of dust, as pure plaster repels Marble, and causes it to swell out and burst. These are joined together by cramps and gudgeons of iron and copper, which should be carefully covered, in order that the oxides may not spot the casings.

Mounting is an important point, for the Marble worker as well as the proprietor. It is not uncommon to see mantels broken by the force of the plaster, and the angles and sharp arris of hearths are almost always broken off by the carelessness of the masons, who trouble themselves less, as they incur but a trifling responsibility.

Marble chimney-pieces are, or should be, lined with lias stone or plaster; this is the same stone which is generally used in bands for pavements.

 

ON THE MANNER OF WORKING MARBLE.

62. The first care of the Marble worker should be to procure those Marbles best suited by nature for his work, whether purchased in the block, or, as is most usual, in slabs of different thicknesses.

When in the workshop, he should examine each piece, note its beauties, and endeavor to hide its defects, before even cutting or working it; this is a very important point, both for his own interest and that of the art. He should, when chance beauties are found, endeavor to cut them into two or three parts, in order to multiply them; the height of the art consists in cutting them in such a manner, that these happy accidents may be reproduced on both sides, and in the middle of the mantel. But this rarely happens, for the artisans cut the Marbles in the most economical manner, and this cutting throws these accidents in the strangest positions.

This can be understood when we consider the calculations of most Marble workers. Thus, let us take for example a block from which two console-tables are to be made. There is a beautiful collection of veins in the upper part; we saw it beveling, in order to divide the happy accident; it is reproduced, in truth, but it is on one side on the top, and on the other the bottom of the console.

The best way will be to have two such pieces, and to cut them uniformly; but to do this, it is necessary to be well served in the quarries, where the workmen can see the exact contents of a block, from the one which preceded its extraction and that which remains.

If the Marble worker chooses to order his Marbles ready cut, he must take such as are sent to him; and, instead of making his own choice in the quarry, he is never sure of obtaining the finest, and often chances to receive the most defective, for the simple reason that the finest blocks are often selected before they are cut.

Marble in slabs is almost always better sawed than that which is cut up in the workshops, because the tools of the large establishments are always better mounted, and better managed than those of the smaller ones; and I call all Marble yards small in comparison with the quarries, whatever may be their private importance.

63. It is not uncommon to see works in Marble yards which were not executed there; they are sent there ready made, and even polished. It only remains to the artizans to double them, and to decorate them in the tastes of the purchasers; and they are often spared even this trouble by the furnishers, who employ themselves in the decoration as well as the execution of the most exquisite works. There is one great advantage in this; the wholesale furnishers have greater facilities, a more extensive choice, and less expense, and if a piece breaks from a defect or accident, it can be replaced by taking another from the block from which it was extracted; whereas, on the other hand, it would be necessary to order it at a great expense, and with an uncertainty of finding it, if the accident should happen in the Marble worker's shop.

Whatever may be the article which is placed on the bench, whether console, mantel, or tablet, all are worked in the same manner; with the mallet for rough-hewing, the chisel and burin for boasting and finishing, the sand-stone for planishing, and the pumice-stone and cushion for polishing.

64. Besides the tools of which we have spoken, the Marble worker has in his shop pieces of sandstone, hone, and pumice-stone, prepared in the best manner to glaze smooth surfaces, to round and groove mouldings, to destroy marks, stains and roughness, and to prepare a brilliant polish which will draw out all the beautifies of the Marble, without concealing any of its defects.

When the piece is finished, and the flutings well grooved and uniform, the dust of baked clay, called rabat, of which we have spoke before, is used. This dust should be well sifted, and rubbed over the Marble, either with a piece of sandstone prepared for that purpose, or with a coarse linen cushion, which should be moistened from time to time.

The workman sees the effect of his labor every moment, when the marble is of good quality; but when otherwise, he can only obtain an imperfect polish; difficulties occur; soft parts drop off, mastics spring up, cracks become visible, and it is exceedingly vexatious when, after having lost much time, and wearied several men, the Marble worker is compelled to reject the stubborn and defective piece.

The more inferior the quality of the Marble, the longer and more difficult is the labor. When it is good, the artisan soon completes his task; he congratulates himself upon his work; but a little time is needed to finish the work so well begun; a few strokes of the rabat and of pumice-stone, and then the cushion, powdered with emery dust for the colored, and powder of tin for the white Marbles, or, which is still better, substitute, as we said before, a piece of lead, by which a finer and more durable polish will be obtained.

There are more expeditious methods which are employed in inferior workshops, but we shall say nothing of them, except that they are a discredit to the establishments which employ them.



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