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Bathsheba Grossman

artist statement | technical statement | process



process

I begin by contemplating a shape: maybe a familiar solid such as the cube, or a more esoteric one like the snub cube or rhombic dodecahedron. I think about it with some modeling clay in hand, and perhaps some possibilities develop; eventually something emerges that might be interesting to build. Sometimes it isn't easy to visualize, but usually I can at least indicate my idea in the plasticene well enough to remember it.Next I need a CAD design. I make this by re-modeling the piece, rather than attempting to digitize it, as no scanner can pick up all the involutions of these forms. Here I fine-tune the design, making precise what was rough in the clay, nailing down proportions and details. This is the longest and hardest part: many many days can go into the model, and when I finally see it printed, as often as not it goes back to the drawing board.

When I have the model complete in the computer, I print it on my 3D printer, or if the piece is to be large, send it to a service bureau with a bigger printer. In either case, a physical model is fabricated from my CAD design by building it up in layers, one layer at a time. This additive method allows very free geometry; it's not nearly so limiting as CNC methods in which the piece is carved. During the build, support for undercuts is provided in various ingenious ways. The machine I have, a Solidscape Modelmaker II, builds support structures in a different material from the actual part, and the supports are dissolved away in a solvent bath after the build is done.
The result of the prototyping process is a strongly grained model, showing the layers it was made with, that can look a little like rough wood. The material is plastic or wax, and it may be more or less durable, but in no case is it pretty. The next step is to cast it into a material that is both aesthetic and archival: metal. This is done by the lost-wax method, an ancient and flexible casting process that can handle almost any geometry. The disadvantage to this method is it destroys the original model (hence "lost-wax"), so a new wax is required for each casting. For most sculptors multiple waxes models can come from a mold, but since that isn't possible for my designs, I build a new prototype for each piece.

I finish the rough castings with hand and power tools: files, grinders, polishers, an occasional weld. The piece is darkened with a hot chemical patina. In some areas the texture is left intact for a rich surface, in others I abrade it lightly, and for highlights it's polished away entirely. Finally the piece is lacquered to protect the finish, and it's done: my geometrical intuition has been realized in the physical world.