Charlie and the Chocolate Factory (2005)

“The most important thing Tim said about the chocolate river,” recalls Joss Williams, was “‘make it look good enough to eat,’ and that’s how we approached it, to look as yummy as possible.” For the effects supervisor, that meant managing “viscosity, looks, color testing and safety issues,” not to mention logistics, quantity, transportation and storage.

The option of making the chocolate off-site and bringing it in via tanker was quickly dismissed, as calculations estimated a need for 40 tanker trucks. It seemed a better plan to manufacture and store the stuff on site. As for mixing it, conventional cement mixers proved inadequate. They needed a vessel that could mix three or four tons at a time, which they found, ironically, in the form of commercial vats designed for mixing toothpaste, that could blend as many as 12 tons at a time and store 20,000.

Altogether, production required a constant supply of more than 200,000 gallons of flowing chocolate; approximately 32,000 for the waterfall and 170,000 for the river, which measures 180 feet long by 25-to-40-feet wide, and is nearly 3 feet at its deepest point.

Without revealing the exact recipe, Williams acknowledges experimenting with mixtures of water and dietary cellulose, with various food dyes to achieve the right look and texture. “Color to the eye is different than color on film,” he explains, “so we tested through a whole pattern of shades to get exactly the right one.” Once prepared, the mixture was constantly cleaned and tested daily by a local laboratory “to make sure it was safe for the company to work with and eat.” Only half-joking, he adds, “we had to keep the bugs down to an acceptable level. There’s about as many bugs in it as you’d find in an airline sandwich.”

For the scene in which Augustus Gloop tumbles into the chocolate river and is subsequently sucked up through an intake pipe to another part of the factory, young Philip Wiegratz was slowly conditioned to the unusual sensation of floundering in melted chocolate. “We started Philip in a small tank in the workshop” says Williams. “Then we tested him in the fat suit that he wears as Augustus; it couldn’t be too buoyant or he’d float, and it couldn’t absorb the mixture and become an enormous weight around him. Probably worst of all, from his perspective, was that once this stuff gets into your ears you can’t hear very well.”

As the scene progresses where the camera cannot follow, the practical set gives way to a CG rendering of events, with a virtual Gloop being squeezed into the narrow space and then spat upwards through the tube – all of which involved Nick Davis and his team with their own issues of color and viscosity, not to mention duplicating “liquid dynamics” in the computer.

Taking a big-picture approach, Davis maintains that, “software can help you break down the physics. You can plug in the known parameters – melt speeds, drip speeds, pour speeds, mass and weight, which helps a lot. But at the end of the day there’s always a human, artistic side to it, where you just look at it and say ‘hmmm, that’s too fast’ or ‘that’s too shiny.’”

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