It doesn’t take an arson inspector to see that the blaze in Backdraft isn’t your ordinary cinematic ball of fire. In the most incendiary sequences, the fire doesn’t just burn uncontrollably, it breathes, hisses, slithers under doors, and lashes out when cornered or trapped. And it performs the vast majority of these feats without any help from postproduction special effects. This fire is the real thing. Under the direction of Ron Howard and his crew, Backdraft became, in effect, the thinking pyromaniac’s Towering Inferno.
Three months before shooting started, Backdraft‘s FX crew began testing a witch’s brew of flammable substances — alcohol, kerosene, diesel fuel, propane — on a specialized ”burn stage.” They wanted a fire that was dirtier and more realistic than the bright gas-jet flames usually seen in films. To harness their volatile fuels, the crew built steel tanks that sprayed the liquids through a nozzle before igniting them four or five feet from the machine — much the way a flamethrower works. The largest of these tanks was called ”Big Bertha” for its 100-gallon capacity and its awesome ability to discharge a 60-foot-by-20-foot wall of fire.
”The force from Bertha’s dump (pressure release) valve alone was enough to blow the walls off of sets,” says special effects and pyrotechnics creator Allen Hall. ”If it wasn’t tied down, it would rocket across the room.”
To pump up the conflagrations even more, the crew built a gadget described by Backdraft writer (and ex-fire fighter) Gregory Widen as ”a reverse vacuum cleaner that looked like an old record player with a big cornucopia cone.” Dubbed ”Ash-o-matic,” the device spewed smoke and burning bits of cardboard into the air to simulate the swirling ash of a real fire.
Not all the flames were the result of mechanical wizardry. ”We must have used 1,000 gallons of rubber cement that we would douse the set with and light,” Widen says. ”It wasn’t real high-tech.” Clay Pinney, one of the special effects foremen, elaborates: ”The stuff was called Petronio’s shoe cement. We went through a couple of hundred cases of it. I’m sure the distributor thought 50 new shoe stores had opened in Chicago.”
Even with his commitment to realism, director Howard was not above a little set manipulation. The most obvious example is reflected in the scenes in which William Baldwin’s character watches an amoeba-like flame roll out across the floor. ”Ron was trying to capture the fire through Billy’s eyes, because his character saw it differently from everyone else,” Pinney says. ”In a normal setting, all of the heat and smoke rise very quickly and you get a normal flame. To get that different look, we inverted the room so that the furniture was on the ceiling.”
Ultimately, visual effects gurus from George Lucas’ Industrial Light & Magic were enlisted for a few particularly tricky scenes superimposing the actors over images of flames filmed separately. The aerial shot of William Baldwin diving to safety off the collapsing chemical warehouse roof was one of the few sequences that involved a miniature set. Still, Pinney says, ”Ninety- five percent of what you see was filmed live on location.”
The fiery production was remarkably free of mishaps. One of the closest calls occurred during the exterior shot of the warehouse blaze. ”When we first turned on the fire it blew out all the windows on the floors above us,” Hall recalls, ”and it got so hot it melted glass in the window frames, popped out big chunks of concrete, and caused structural damage to the building.” (The warehouse had already been scheduled for demolition.) Nevertheless, except for minor burns and singed eyebrows among both cast and crew over the course of the 4 1/2-month shoot, there was only one accident to report. ”We were cleaning up after the first fire,” Hall says. ”One of the guys tripped over a hose and broke his ankle.”