'Harry Potter and the Philosopher's Stone' special effects challenges revealed

Harry Potter and the Philosopher's Stone has carved up a home in the hearts of millions of kids. But little was known about the efforts that went in to create the magic on the big screens.

Speaking to Evening Standard, the special effects supervisor John Richardson revealed the hardships he faced in creating the illusion of the Great Hall of Hogwarts candles that tend to float there.

"All my life I've tried to do things in-camera as much as possible because I think it adds a reality to the film," the Superman special effects supervisor added.

"We ended up hanging 400 floating candles with real flames burning. They were all hanging on rigs so that they floated up and down, he continued.

"We had to make the wires as thin as possible so they wouldn't photographed so we used a very fine tungsten wire and put them all in the hall."

The 73-year-old said, "We hung them only over the tables, not where the children would sit, just in case anything fell or dropped or whatever. We put them all in, and it looked terrific.

But due to a technical issue, the Oscar winner revealed the real candles were switched with CGI.

"What we hadn't allowed for is that Leavesden [where it was filmed] wasn't really a proper film studio like it is now; it was a series of old aircraft hangers where they built aircraft in the Second World War. So they were a little well-worn and draftee!

"There was a particular draft coming from one side of the set coming in through the walls of the stage, and it was blowing the flames of the candles onto the tungsten wires, and it caused two of the wires to break," the technical expert continued. 

"I don't think the candles actually fell because they were still hanging on one wire, but of course, it did concern everybody that there was a possibility that a candle could fall and hit one of the kids because, at that time, they were all 10 years old."

"I think we shot for a few days with the real candles so they were actually in the first movie and then it was decided that we would take them out and put them in from CGI from there one," he added.

The supervisor also boasted a variety of projects in his credits, including James Bond movies and Willow.

In 1987, the supervisor bagged the Academy Award for best visual effects on Aliens.