“Imagine the interior of an old, rusty warehouse, and a huge semi-circular curved brick and steel wall, 35' wide [and 20' tall],” says LD Chris Parry, describing the Neil Patel set he lit at the Alley Theatre in Houston. This evocative and realistic set for Hamlet, a play that transpires mainly indoors, became problematic for Parry during the play's few outdoor scenes. He thought about projecting clouds to suggest a sky, but the distressed wall wasn't bright enough.
Then he had an idea. An impossible idea.
On the stage floor, a 2'-wide grating surrounded a 30'-wide semi-circular turntable, 18" off the deck. “The audience didn't know it was a turntable until it moved,” says Parry, who knew he could use the grating for smoke feed as well as lights. If smoke would rise from the floor around the base of the wall, drifting up the semi-circular wall to create an alternate cyc — and go nowhere else — the smoke would resemble moving clouds. But smoke goes where it will, and it normally comes downstage and fills the room. Ah, there's the rub.
Could Alley lighting supervisor Clint Allen and his crew take arms against this sky of trouble and get the smoke to move up and out?
Allen says Parry prefaced his request with the disclaimer, “I don't know if this can be done,” and that's why Allen knew he had to do it. “Anything can be done, especially if you tell me it can't,” Allen insists. The crew had six months to experiment. “We spent a lot of time just learning how the air circulated in our space and how to bend it to our will with our prototypes.”
“All told, there was about 40' of wall length, which called for a 40' smoke curtain.” says Allen, adding that expanded steel plating covered the moat between the turntable and the walls, allowing them to “surround the turntable with light and the upstage half with a smoke curtain.”
“We used equipment we already had, including three High End Systems F100 fog machines with cold flow fluid and two CITC Vornado Director fans. These fans push a directed wind about 70'. We added to our equipment with two 20'-long 10" flexible tubes, two big trash bags, six attic exhaust fans, and about 100' of 8" dryer hose,” says Allen. “The cold flow fluid seemed to be the lightest fluid and would rise the quickest, was the most transparent, and dissipated the quickest. All the other fluids did exactly what they were supposed to, but only the cold flow worked for the curtain.” Six gallons a week did the trick.
Crews capped the most downstage end of each tube. Once the tubes were in place, they drilled holes in them at 1" intervals. “This way, we were sure all the holes were pointing up and the caps forced the air up instead of out through the end.” To reduce the blowback of the fans, they attached trash bags to the ends of the tube closest to the fans and placed all the equipment below the deck. “I wanted the exhaust holes in the tube small to give the fog good lift with high air pressure, but there was too much air going into the tubes and the excess air blew smoke out of the back of the fan. The trash bags acted as a reservoir to keep the smoke in front of the fan and worked beautifully,” Allen says, adding that he needed quite a bit of gaff tape to secure a trash bag to a fan. “Scenery made the platforming over the fog contraption easily removable and that came in handy many times,” Allen notes.
Parry wanted the effect to last for entire scenes involving the ghost. “In order for the fog curtain to last for more than a minute, we had to use three fog machines to avoid time out with the duty cycle. We used three F100s in an effect that ran each machine for 40 seconds on and 20 seconds off. With this timing and the machines at full, we were able to have a continuous wall of smoke for about 20 minutes.”
They used Mylar to create a funnel behind the fans to get the three machines to go evenly into the two fans, creating an even distribution of smoke to each half of the fog curtain. “[There was] one large area of pull instead of two smaller areas of pull,” Allen explains. They placed 6'8" tubes in the tension grid, connecting these to six large attic exhaust fans, directly above the tubes under the deck. “We modified these fans to be mounted upside down and placed them as far offstage to cut down on noise and exhaust the smoke as far from stage as possible,” says Allen. “With only the fog contraption below the deck, the smoke would only rise about 8'-10' before it lost lift and fell back on itself. When we added the exhaust fans in the grid, the smoke rose all the way to the grid (22'6") and was pulled offstage. When we stopped the effect, the smoke would clear the stage in about 20 seconds.”
Parry was impressed and delighted. “A tall order. But I got it!” he says. “Amazingly successful!”
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