The Cloud Tank: Historical Film Effects Technique for Creating Atmospheric Visuals

A cloud tank is basically a big water tank. It's primarily used to create a wide variety of atmospheric effects, mainly clouds, hence the name.

Back in the old days this was a great way of creating organic shapes, which would otherwise have to be done with hand-drawn animation or perhaps smoke.

A cloud tank shot starts with a big glass tank filled with water. Into this water, you inject some kind of colored liquid - usually white or black paint, or sometimes colored dyes.

The cloud tank was used extensively in the 1970s and 80s, most famously in films like 'Close Encounters of the Third Kind' and the original 'Star Wars' trilogy.

Today, cloud tanks are largely obsolete, replaced by computer-generated effects that can create similar visuals with more control and less mess.