Skinner Butte Park's 45-foot-tall basalt columns have attracted rock climbers for decades. So when the city of Eugene, Ore., decided to build Riverplay, an innovative playground in another area of the park, a replica of the columns, sized just for kids, was part of the plan.
The job went to Ray Robinson of Deadwood, Ore., who recently completed 15 “basaltic” climbing rocks made of concrete.
First, Robinson fashioned the column-like sculptures out of rebar and expanded metal lath. Next, concrete was pumped into the hollow columns. The rough concrete columns were then covered several square feet at a time with a 70 grit silica sand, lime and cement mixture (which he calls frosting) and haphazardly troweled, leaving imperfections. After dusting the mixture with a release agent, he then patted the soft concrete for texture with a self-made latex rubber pad.
Then, with six colors of the best latex paint money can buy — black, white, raw umber, burnt umber, raw sierra and burnt sierra — he began the intricate coloring process of mixing mist and random blobs to transform the columns of concrete into the “rocks” they've become today. Armed with a hose in his left hand and a hand-spray atomizer in his right, he methodically applied 14 different shades of paint, starting with the lightest and working his way to black.
“The coloring is more difficult than shaping the rocks,” he says, adding that his technique is largely intuition. “It's like backpacking into an area you've never been before. You know what to take and how to survive, but you don't really know how you're going to do it until you get there.”