METHODS OF FINISHING THE FACES OF CUT STONE.
In architecture there are a great many ways in which the faces of cut stone may be dressed, but the following are those that will be usually met in engineering work.
Rough Pointed. When it is necessary to remove an inch or more from the face of a stone it is done by the pick or heavy point until the projections vary from to 1 inch. The stone is said to be rough pointed. In dressing limestone and granite this operation precedes all others.
Fine Pointed. If a smoother finish is desired rough pointing is followed by fine pointing, which is done with a fine point. Fine pointing is used only where the finish made by it is to be final, and never as a preparation for a final finish by another tool.
Crandalled. This is only a speedy method of pointing, the effect being the same as fine pointing, except that the dots on the stone are more regular. The variations of level are about inch and the rows are made parallel. When other rows at right angles to the first are introduced the stone is said to be cross-crandalled.
Axed or Pean Hammered, and Patent Hammered. These two vary only in the degree of smoothness of the surface which is produced. The number of blades in a patent hammer varies from
6 to 12 to the inch; and in precise specifications the number of cuts to the inch must be stated, such as 6-cut, 8-cut, 10-cut, 12-cut. The effect of axing is to cover the surface with chisel marks, which are made parallel as far as practicable. Axing is a final finish.
Tooth Axed. The tooth axe is practically a number of points, and it leaves the surface of a stone in the same condition as fine pointing. It is usually, however, only a preparation for bush ham mering, and the work is then done without regard to effect, so long as the surface of the stone is sufficiently levelled.
Bush Hammered. The roughnesses of a stone are pounded off by the bush hammer, and the stone is then said to he "bushed." This kind of finish is dangerous on sandstone, as experience has shown that sandstone thus treated is very apt to scale. In dressing limestone which is to have a bush hammered finish the usual sequence of operation is (1) rough pointing, (2) tooth axing, and (3) bush hammering.