Thermoplastic forms stand in for bricks, stonework, all manner of scenery while maintaining
paintability, impact resistance, and recyclability.
Whether it’s the 1954-era brick buildings in the Martin Scorsese/Leonardo DiCaprio thriller Shutter Island, turn-of-the-century cobblestone roads in the movie Beloved, or the bare cinder-block jail cell in a television crime series, set designers rely on lightweight, rigid materials to deliver the look and feel of the real thing. They turn to specialized suppliers like Provost Displays, Norristown, Pa., for architectural elements fabricated from lightweight, thin-gauge, rigid thermoplastic.
The company vacuum forms plastic panels for theatrical, film, and photographic scenery. Standard designs include stones, building materials, windows, doors, tiles, as well as 16 types of brick. Other items are manhole covers, rafters, Egyptian panels, deer heads, radiators, and fire hydrants.
Molds for some designs are hand-sculpted from high-density foam and then sealed with reinforced two-part epoxy resin. Other molds are taken from plaster casts of real items. Continuous-pattern designs, like brick, have interlocking soldiered edges. The company also forms corner pieces.
Manufacturing begins with a 52-in.-wide, 300-lb roll of 0.030-in.-thick thermoplastic alloy from Boltaron, Newcomerstown, Ohio. The sheet is typically specified in white with a smooth, matte finish. Technicians at Provost paint the sheet using a water-based latex paint.
The next day, Provost technicians preheat the sheet to 315 to 335°F. Then they apply about 350 psi of vacuum below the sheet, while the sheet is pulled over the mold where it cools sufficiently to retain every detail of the mold’s shape and surface. During this process, the paint bonds with the plastic.
Finished panels are typically shipped flat and measure 4 × 12 ft. The company can also produce 4 × 8-ft and 4-ft-square sheets. On the stage or set, crews trim the panels with scissors or utility knives and mount them to sheetrock walls, wood paneling, and theatrical flats using staples, adhesives, or screws with washers.
Provost’s owner, Ardia Dayton, says the company uses Boltaron sheet for its formability. The material has little thin-out on outside corners or in recesses.
“For example,” she says, “we vacuum form a scallop-shell panel with a 12-in.-deep draw, and it picks up every detail of the mold.” The deepest recess Provost has drawn is 18 in.
The Boltaron material also has good tensile strength, scratch resistance, and 20-ft-lb/in. impact resistance. The material was put to the test on the set of “Beloved,” when set designers laid vacuum-formed cobblestone panels from Provost Displays over an existing Philadelphia street. They spread dirt over the panels, and actors, horses, and rooting pigs walked over them during filming.
All of the panels are reusable and recyclable and can be repainted and repurposed for alternate sets.
Source : machinedesign.com