Why Real Explosions Don’t Look Like Those in Movies

In a fiery episode of Things You Might Not Know, host Tom Scott examines why explosions in real life don’t look as big as the ones seen in Hollywood films. Scott consulted with a professional pyrotechnician who helped him set off explosions of each kind.

Explosions on film are made to look good: fireballs and flame. In reality, though, they’re a bit disappointing. Here’s how Hollywood does it. Produced with an experienced, professional pyrotechnician.

Despite being incredibly dangerous, the real explosion of plastic explosive but didn’t appear very big at all. The second, less deadly explosion, which used a directed detonating charge to set off a bag filled with a flammable gas mixture, packed a great big visual punch.

We’ve just blown up one kilo of Semtex 1A, which is a PETN-based plastic explosive. Now that’s a real military explosive. So for a Hollywood effect, we don’t actually use the Semtex because it does a lot of damage. It’s designed to do damage for its military purpose. We don’t want that. We want something that looks nice but does the minimum amount of damage possible. So what we’re going to use is some detonating cord to burst a bag full of petrol,
and that will be ignited as it goes out by an ignition charge off to one side.