MOTHER-OF-PEARL.

Poverty Bay Standard, Volume I, Issue 63, 11 February 1884, Page 3

MOTHER-OF-PEARL.

(British Mail.) Thim beautiful material, which is so mudi used in many kinds of artistic productions, is chieflv obtained from the pearl ovsters (Metetnjrina mdryarifera), which are found in the Gulf of California, at Panama and Colagua, at Ceylon and Madagascar, at the Swan River in Manila, and at the Society Islands. The black-lipped mussels from Manila bring the best prices. The Society Islands produce the silver-lipped mussels, and Panama the socalled “ Bullacks.” The peculiar and varied tints and colors exhibited by mother-of-pearl are due to the structure of the surface, which is covered With innumerable fine plates—often several thousand to the inch—which break up the rays of light falling on it, and reflect it m all (liferent tints. The oyster pearl has a lau.tllar structure, and can actually be split off in scales, but they are rarely divided in this way, at there is always danger of destroyirg it. In working mother-of-pearl, says Wieck'a Illustrated Art Journal, the saw, file, si d polishing-stone play the principal parts, A mussel shell is selected that is covered with the pearly substance to such a thickness as is J ecesesty for the work in hand. The f quare or angular pieces are sawed out with a Fmah saw, the piece being held in the hand or clamped in a vice. Buttons and similar iound pieces are cut with a crown saw attached to a spindle. All the tools employed in working mother-of-pearl must be kept continually moist, to prevent their stick* ing fcst. The pieces are generally shaped on a polifhiug stone, the rim of which must be ribbed to avoid daubing and smearing. The stone, of course; must be kept wet while in use; a weak sbapCuds works better than water alone. When the pieces have been brought to the proper shape on the stone, they are then polished with pumice and water. In many cases it is well to shape the iece of pumice so as to fit the form of the -r article to be polished, and then the latter can be fattened to a handle and rotated in a lathe, jt is afterwards polished with finely-powdered pumice oh a cork or wet rag, while the final polishing is done with English tripoli, moistened with diluted sulphuric acid. The acid brings out the structure of the pearl very beautifully. In many articles it is necessary to use emery before the tripoli is applied, and then employ oil instead of acid, Knife and tasor handles have the holes bored in them after, they are cut in the proper shape, and k. kre then lightly riveted together, polished on the stone, and finished as before described, In many workshops the polishing is performed on wheels covered with a wet cloth, which holds the polishing material. For common work some pulverised chalk or Spanish white is substiuted for the English &other*of-pearl is frequently etched like copper. The design is put on with asphalt tarnish; which protects the parts that are not to be etched; and the piece is then put in nitric acid. When the exposed portions have* been sufficiently corroded by the acid, the article is rinsed with water, and the varnish dissolved off with turpentine or benzole. Thin pieces of pearl which are to have the same shape are glued together, and all out and boxed at once like a single piece, and afterwards separated by putting them in hot water. t In ordinary inlaid work of mother-of-pearl, Scales dr Very thin pieces of pearl are fastened on iron or some foundation, usually made of papier-mach6, with Japanese varnish. The plate is first cleansed and dried, then coated with varnish ; when the latter is nearly dry, cut pieces of mother-of-pearl are pressed into the varnish by the artists so as to adhere to it; The plate is then baked in an oven until the varnish hardens, when a new coating is put over the entire article, which is then polished again. Besides the white and aurora-like mussels above mentioned, the sparkling green snail shells sometimes find use. These exhibit dark or light tints of green, yellow, or pink, or one shade passing into another.