There are several YouTube videos that claim to show cars painted with "Paramagnetic" paint which supposedly used an electrical current to change the color of car paint. Many of these are quite realistic looking, as the camera moves around the car, and only the paint changes color in the scene. Because of the high quality videos, many people, and even some car web sites, have been taken in by the hoax.
In fact it's just a very simple trick in Adobe After Effects, the "Change To Color" effect, where you just have to pick the color you want to change from, and the color you want to change to, and Adobe will do all the rest in a matter of seconds. To animate the color, all you have to do is change the "to" color at different points in the video, and Adobe takes care of that too. It's really one of the simplest things you can do in After Effects.
It took me about fifteen minutes to find a tutorial, and make my own version using a network cable. So long as the object (the car, or the cable in this example) is a unique color, then nothing else is needed.
With the end result:
The origin of the hoax dates back to a 2007 article in Motor Authority:
It's unclear where that original claim came from, however there is a company called "Litcoat" with a current web site that claims to be able to sell you a pdf containing the secret of paramagnetic paint. Their process looks rather dubious though, and there's no evidence it actually works.
Paramagnetic paint changes color at the touch of a button
Posted on Wednesday 7 November 2007
One of the hardest decisions when picking a new car is choosing the right color but the day when cars will be available in multiple colors could be here sooner than you think. Scientists have developed a new coating called ‘paramagnetic’ paint that has the ability to change colors at the touch of a button. One carmaker looking into the technology is Nissan, which has already developed a self-healing paint.
Before the vehicle is painted, a special polymer containing the special ‘paramagnetic’ iron oxide particles is applied to the car’s body. An applied electric current then adjusts the spacing of small crystals within the iron oxide particles and therefore affects their ability to reflect light and change color.
The only technology that remotely resembles this is electroluminescence, where a layer of semiconducting phosphor is sandwiched between two conducting layers, with the top layer being transparent. These layers can be very thin, and some companies have been developing methods of painting them onto curved surfaces. It's a fiddly process though, and does not actually change the color of the paint, just makes it emit some light.
Here's the tutorial by Justin Jimmo. This is just a little more complex as there is a car in the background that is the same color. So that needs masking out. But it still only takes Justin a few minutes.