As cool as it might look (to those who actually do look), this is definitely not one to try at home.
For the latest instalment in his “Things You Might Not Know” series, YouTuber Tom Scott brings in a chartered explosives engineer to talk about Hollywood movie explosions — and specifically, the little tricks they use to make them look all fiery and impressive (and very much not like real life, as Scott demonstrates at the video’s beginning).
“We’ve just blown up one kilo of Semtex 1A, which is PETN-based plastic explosive,” says engineer Stephen Miller after what looks like a fairly underwhelming explosion. “Now that’s 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 as minimum amount of damage possible.”
In the end they use a bag of petrol which is ignited by an ignition charge facing in the direction of the camera.
“The reason we’re getting a bigger effect using less explosive is because of the fuel,” Miller explains. “We’re putting that in there because that will catch fire, be big yellow flames, lots of dirty black smoke (…) the visual effect is from the cloud of fuel igniting and the explosive is just used to create that cloud.”
The end result? A flaming ball worthy of Die Hard (although Scott’s cheery smile as he ignites it does seem a tad out of place).