For shallow circular forms draw a circle.

For low cylindrical forms draw a rectangle; subdivide this if desired by a unit of measurement into two horizontal divisions.

For high cylindrical forms draw a rectangle; subdivide this if desired by a unit of measurement into two or three horizontal divisions. Rule 5e.

(_b_) Design simple contour enrichment based upon these units of measurement.

(_c_) Locate zone of enrichment.

(_d_) Draw inceptive axes:

For square or rectangular areas draw diameters, diagonals, or both.

For shallow circular forms draw radii of the primary circle; concentric circles for bands.

For low cylindrical forms draw the elements of the underlying cylindrical form for extended borders or lines paralleling the top or bottom of the primary ma.s.s for bands.

For high cylindrical forms draw inceptive axes similar to low cylindrical forms.

(_e_) Locate points of concentration in these inceptive axes.

(_f_) Determine manner and amount of surface enrichment.

(_g_) Add leading lines and develop these into surface enrichment.

(_h_) Make potter's working drawing, full size (See Plate 26).

Add the necessary amount for shrinkage and otherwise prepare the drawing for potter's use.

(_i_) Make a paper tracing of the surface enrichment for transfer to clay body and cut a zinc or tin template as a contour guide in building the form.

SUGGESTED PROBLEMS

Design a cider or chocolate set with appropriate surface enrichment.

Design an architectural tile 6 in. by 9 in. for accenting a brick fireplace in the home.

SUMMARY OF RULES

Rule 9a. _Surface enrichment of clay must be so designed as to be able to withstand the action of heat to which all ware must be submitted._

Rule 9b. _Incised, pierced, and modeled decoration in clay should be simple and bold and thus adapted to the character of the material._

Rule 9c. _A border should not be located at the point of greatest curvature in the contour of a cylindrical form. The contour curve is of sufficient interest in itself at that point._

REVIEW QUESTIONS

1. Compare the surface enrichment of clay with that of wood.

2. State a major requirement of a good pottery design.

3. Give the broad divisions into which it is possible to divide the decorative processes of clay surface enrichment.

4. Name and briefly describe eight methods of enriching the surface of clay.

5. What precautions should be exercised with regard to the use of incised, pierced, and modeled decoration?

6. Should a border be placed at the point of greatest curvature of the contour? Give reasons.

7. Name method of cla.s.sifying structural forms in clay into four groups.

8. State problems and possible zones of enrichment in each group. Give reasons for choice.

9. State type of design unit, conventionalized, natural or artificial forms, location of inceptive axis, points of concentration, and process for each zone of enrichment.

10. What is an element of a cylindrical surface?

CHAPTER XIII

SURFACE ENRICHMENT OF PRECIOUS METALS

SMALL FLAT PLANES

[Sidenote: Base and Precious Metals]

Chapter XII referred to clay as a free and plastic material adapted to a wide range of surface enrichment processes. Metal as a more refractory material offers greater resistance to the craftsman and is relatively more limited in its capacity for surface enrichment. As was the case in the consideration of contour enrichment for designing purposes, it is necessary in the consideration of surface enrichment to divide metal into two groups: precious and base metals. As the field of design in both base and precious metals is large, we shall consider the surface enrichment of _precious metals only_ in this chapter.

[Sidenote: Divisions for Enrichment]

Following an order similar in character to that used in clay designing, problems in both base and precious metals may be divided into four cla.s.sified groups as follows: flat, square, rectangular, or irregular planes; shallow circular forms; low cylindrical forms; high cylindrical forms. Designs included in the first group, flat planes, comprise such problems as are typically represented by tie pins, fobs, rings, and pendants. The design problems presented by these examples are so important that it is wise to restrict this chapter to _flat planes_.

Rule 10g. _The inceptive axis should pa.s.s through and coincide with one axis of a stone, and at the same time be sympathetically related to the structure._

Rule 10h. _The position of the inceptive axis should be determined by: (1) use of the project as ring, pendant, or bar pin, (2) character of the primary ma.s.s as either vertical or horizontal in proportion._

[Sidenote: Inceptive Axes and Points of Concentration]

The semi-precious or precious stone is commonly found to be the point of concentration of these designs. The inceptive axes of tie pins, pendants, and fobs are generally vertical center lines because of the vertical positions of the objects when worn. The inceptive axes, moreover, should pa.s.s through the point of concentration and, at the same time, be sympathetically related to the structure. Rings and bar pins are frequently designed with horizontal inceptive axes, so determined by their horizontal characteristics and positions.

The point of concentration for tie pins, pendants, and fobs in formal balance, in addition to coinciding with the inceptive axis, is generally located above or below the geometric center of the primary ma.s.s. The point of concentration for rings and bar pins is placed in the horizontal inceptive axis and centrally located from left to right.

[Sidenote: Typical Processes of Enrichment]

[Sidenote: Economy of Material]

As a step preliminary to designing, and in order that the enrichment may be conventionalized or adapted to conform to the requirements of tools, processes, and materials, it is now imperative to become familiar with a number of common forms of surface enrichment in metal. There are eight processes frequently encountered in the decoration of silver and gold: piercing, etching, chasing or repousseing, enameling, inlaying, stone setting, building, carving. To these may be added planishing, frosting or matting, and oxidizing as methods employed to enrich the entire surface. Economy of material is of prime importance in the designing of precious metal and, particularly in gold projects, conservation of the metals should be an urgent consideration in all designs.