Copper Printing

Yesterday I went with some friends to New Bedford Open Studios, and we had an amazing time. I especially enjoyed learning how to impress materials into copper at Sue Kowalski's studio (which is beautiful in itself -- it's in an old church!). We placed dried plants on copper strips, and then put a harder brass strip on top and ran it through a roller press. Because the copper is softer, when the plants get squeezed between the two materials they impress their forms onto the copper. I used milkweed pod silk, which is pretty much entirely without substance, so it didn't make much visible effect until I darkened the copper strips with liver of sulfur and buffed off the top layer. The patina stays in the lower indentations made by the plant material and makes the design easier to see. Here are some examples:

Milkweed pod silk

 Milkweed pod silk with some seeds attached (which exploded in the press...)

Shepherd's purse, a much more substantial plant

Sanding off the patina struck me as incredibly like working in the darkroom, and selectively dodging or "bringing up" certain parts of the image. The big difference is that when printing plants with cyanotype or other sun prints, the print is made by the differences in opacity, while with physical printing the print is made by the differences in thickness. Of course, there is a direct relationship in many ways between the thickness of a plant and the opacity; in fact, when we were having trouble placing the plants, Sue reminded us to think of the "shadow" of the design (basically the negative space) to judge whether the design would be too dense. The resulting patinaed prints did look pretty much like what you would get from a sun print, but with added texture.