Marble, such as is used for mantelpiece jambs, is polished in a variety of ways, the choice depending largely upon the nature and quality of the material, which vary greatly. The following method will answer satisfactorily for vein, statuary, Sicilian, St. Anne's. Bardilla, and most of the ordinary coloured marbles in general use. The wrought surface is rubbed with fine sharp sand and water, until all the marks of chisel or saw are removed and an even surface is produced. It is then " grounded " - that is. rubbed with grit stones of varying degrees of fineness, commencing with the coarse or first grit, usually Kobinhood stone; next the second grit, which is a little finer; finishing with snake stone or Water of Ayr stone. Particular care must betaken that in each process of gritting the marks or scratches of the preceding one are removed, so that when the surface is snaked no scratches whatever are visible. The gloss or natural polish is obtained by rubbing with a pad of felt sprinkled with putty powder (calcined tin) moistened with water. The chief factor in this method is persistent and attentive rubbing, and a good polish thus obtained will retain its lustre for years.
For speed and cheapness chemicals are sometimes used for polishing, such as oxalic acid, hydrochloric acid (spirit of salts), and others, but their use is to be deprecated, as the polish soon vanishes and the face of the marble is in some measure destroyed. The polishing of marble adds greatly to its beauty, in as much as its delicate figuring and gradations of rich colouring are brought out and heightened as it were by the process, which gives marble it- value as a decorative material. With regard to the appliances, for mouldings the grits are cut into small strips and sh into hollows and rounds to lit the various members; ami for the polishing bn-s. an old worsted stocking, tightly tied up in a wad. does admirably. For plain facework the grits are in Hat pieces, and are used on traversed over the face. The polishing block is a -ofwoodfrom I6in. to I8in. Long.and l in. wide, with a piece of felt on the underside fastened at each end.