9. The process of smoothing and, at the same time, hardening the surface of the metal with a steel planishing hammer. The hammer strokes give an interesting texture to the surface which may be varied, from the heavily indented to the smooth surface, at the will of the craftsman. The more obvious hammer strokes are not to be desired as they bring a tool process into too much prominence for good taste. Rendering—print desired finish on the drawing.
Frosting
10. A process of sand blasting or scratch brushing a metal surface to produce an opaque or "satin" finish. Rendering—similar to planishing.
Oxidizing
11. A process of darkening the surface of metal by the application of chemicals. Potassium sulphite will supply a deep, rich black to silver and copper. Rendering—see Planishing.
Design of Pins and Brooches
The eleven processes mentioned above are among those which, by recent common practice, have become familiar to the craftsman in precious metals. While they do not cover the entire field, they at least give the beginner an opportunity to design intelligently in terms of the material.
Dependent Surface Enrichment for Pins
[Plate 53] is mainly the enrichment of the flat plane by the addition of semi-precious stones (process six). Whatever surface enrichment is added to this design becomes dependent enrichment and quite analogous to dependent contour enrichment, [Plate 29], inasmuch as it has to be designed with special reference to the shape and character of the stone. [Figures 358] to [363] are examples of dependent contour enrichment; [Figures 364] to [371] are examples of dependent surface enrichment. [Figures 358] to [367] are based upon vertical inceptive axes as appropriate to their intended service. The point of concentration may be located at practically any point on this inceptive axis, provided the major axis of the stone coincides with the inceptive axis. The best results are obtained by placing the stone a little above or below the exact geometrical center of the primary mass.