The Rowena Reed Kostellow Fund

Problem Three: Concavity

“The sculptural exercise that emphasizes concavity explores a relationship which is seldom understood. A talented and intuitive designer may well arrive at sensitive, positive volumes, but unless the important relationship of the negative volumes, or concavities, to the positive forms are explored, his visual solution is only half controlled. In the convexity exercise you were already learning about concavity — about how negative volume affects form. Now, the focus will be on concavity.”

Think about natural elements and the slow erosion caused by wind and water. Make some clay sketches in which concavity establishes the character of the design. Design the surface of the concavity to contrast with the convexity.

“Good art or design rarely looks like it was done quickly. The artist or designer keeps working until all the parts of a painting, sculpture or product relate to each other. That’s what makes art last — regardless of its time. We respect it for its completion and its consistency.”

Choose your most successful sketch and develop it. Use several blocks of clay and combine them. Decide whether you want a predominantly vertical or horizontal composition. Create shapes in which the character is interesting and the inherent and comparative proportions are pleasing.

Establish dominant, subdominant, subordinate relationships. The first big spatial relationship should express the whole design. It should express the character and proportions of the volumes; the rhythmic movement of the volumes; and variety and contrast of curved and straight lines.

Work on contrast. If things are different they must complement each other. It’s much harder to make things that are complementary than to make things that are the same. The complementary relationship must be understood from the very beginning. If you’re having trouble, just hang in there. Take one shape away and see if it looks better without it.

Be aware of the axes. Not only do positive forms have axes, but concavities have axes as well. When the shape of a concavity is strong, it becomes a thing. It’s almost like a positive form.

Do not trap the negative space. It should go around and come out and go someplace else. The space should flow, pushing against the volume in an eroding process, like a river through a canyon. Try to indicate how you’d go through it with the eye. After you have the volumes and the axes right, you can begin to play with one plane against another plane. Then you can play with all the other lines. See how the outside lines relate to the inside lines.

Execute your final design using a salt block or plaster block as your medium. Plaster is OK here. You can afford to work more quickly on the concavity exercise because you can gouge and hollow the material. If you work in salt, use files and sandpaper as you did in the convexity problem.

Although you’re taking away material here, don’t let your form contract like a prune becoming a raisin. You want to increase the presence of the form through its expansive characteristics. Once again, you want to end up with a form that looks larger than the geometric form you started out with.