Composites help create "ghostly" sculpture of bygone time

Sculptor Lawrence Argent of Argent Studios Ltd. (Denver, Colo.) recently completed another of his several Denver-area public art installations, an internally illuminated, translucent composite sculpture called Ghost Trolley. Installed on Colfax Ave. to commemorate the trolley line that operated there until the 1950s, the work was commissioned by the City of Aurora, Colo. to enhance its historic downtown area.

Using a CAD program, Argent rendered a true-to-scale three-dimensional image of a trolley car, based on historical data and photos, then flattened the image. That CAD file was transmitted to Kreysler & Assoc. (American River, Calif.), where it was converted to machine code, enabling the company’s CNC machining center to mill an expanded polystyrene (EPS) foam pattern. According to company president Bill Kreysler, “We were able to use one mold to make both halves of the sculpture, which were then joined back to back to form the completed part, thanks to the design symmetry.”

A clear polyester gel coat supplied by Valspar Composites (Elkhart, Ind.) was first down in the mold, followed by E-glass chopped strand mat (Owens Corning Composite Materials LLC, Toledo, Ohio) wet out with specially formulated clear polyester resin, supplied by Hexion Specialty Chemicals Inc. (Carpentersville, Ill.). Kreysler says that promoter and catalyst levels had to be controlled to avoid discoloration, so the cure process took longer. After LED lights were installed and two steel posts were bonded to one half to form a support armature; the two composite halves then were bonded together with adhesive and clear coated with Permalac polyurethane enamel (Peacock Laboratories, Philadelphia, Pa.).

At the installation site, the armature’s stainless steel posts were fitted over slightly smaller-diameter posts anchored in the sculpture’s concrete foundation, which is set in the street’s center median. At night, the LED lights inside the pale structure cast a ghostly glow of times past.