selective reflection

i guess mi question was incomplete..

There s a way to change the color of a solid at will, and that is reversible?

Imagine a area of x material that can be turned black or white at will, instantaneously.. is that posible?

actually what i was looking for i realize is related to e-paper.

A liquid crystal can turn from trnasparent to opaque. upon application of electrical current.

Photochromic coatings do this upon high light flux.

milo

Interesting stuff:

http://www.alsacorp.com/products/eclipse/eclipse_prodinfo.htm

http://www.colorchange.com/

http://web.mit.edu/newsoffice/2007/lightgels-1021.html

Try electrochromic coating/film

http://en.wikipedia.org/wiki/Electrochromics

You can achieve the desired effect by use of a projector. I personally use a video projector, but you coud use a slide projector.

Nikolai,

This is the basis for Liquid Crystal Displays (LCD's). Research is coming up with a number of materials which can have their opacity/transparency changed and even the wavelengths of reflected light changed. You might do some searching for further information on emerging LCD technology and see where this takes you.

Regards, JMM

If you do mean like e-paper, then take a look at Sony's "White-Paper" technology (I think that's what it's called). The display technology is used in the Kindle reading device. Unlike LEDs or LCDs, white-paper displays can be best seen under light - instead of getting glared out.

Anyway, if curious, go to Amazon.com and look up "Kindle."

Mood rings come to mind

how about those "Code Bleu" T-shirts from the 80's and 90's they were heat activated.

There are some chemicals out there that are either Photo or UV activated. thats how those dorky transitions lenses work.

There are also piezo activated additives to glasses. a small current will change the transparent glass to opaque, similar to liquid crystal I beleive.

And of course thermal and stress activated chromic based pigments and paints.

Another interesting thing about the "e-paper" technology is they can also do white & mirror-reflective. This appears in the Kindle's border, where menus and text is selected. When you move the cursor or select some text or menu, it uses white & mirror!!!

Hi, nikolai!

Without intending to be facetious, but still in the realm of having fun, the answer to your question is to paint the solid a different colour.

Mark

actually when paiting, you are placing another substance infront of the solid.. if you take out the paint the solid will be of the same initial color.

Curses! Foiled again!

Ummm... How about if we dye it?

Mark