Walt Disney was planning to build a mine train ride in Disneyland, it was known as ‘Mine Train Thru Nature’s Wonderland’, opened from 1956 to 1979, when it was replaced by Big Thunder Mountain Railroad. The original mine train went through ‘Rainbow Caverns’ which was an indoor cave with fluorescent waterfalls.

Walt wanted all six primary colors to fall side by side in one big waterfall. He assembled a group of his artists to figure how to do it. Most of the artists, including the lead art director, thought that it was impossible to have different colors of water falling side by side in the waterfall, because they would splash over each other and soon blend into a single muddy color.

Walt, who didn’t like to be told that something couldn’t be done, asked, “Well, is there anyone who does think that this is can be done?” Artist Claude Coats raised his hand, and Walt said, “Ok, you’re now the art director for this project”.

Claude was taking a risk, because he basically promised he could do it without exactly knowing how he could do it. I got a chance to meet and ask Disney Imagineer Tony Baxter about how Claude Coats solved the problem, and he said that Claude used a kind of Brillo pad, which is like a sponge, to reduce the splashing. Walt got what he wanted, even though people thought it was impossible.