Thread: Help? The name of a chemical effect.

"Two pieces of clothing that seem to have matching color while inside the room, but don't have matching color when they are outside?"

Trying to find the name of this effect.
The effect has to be related to the interaction of light and matter...
please help.

For what it's worth: this effect is of course related to the chemical composition of the material of the clothing and especially of any dyes in it, but I think more people will call it an optical effect and not a chemical one.

like Leszek Luchowski said ... optical, rather than chemical ...

and I would add the difference in qualities of light involved in the different locations -

eg; under a low watt "warm" white (3500K) lamp, I've seen dark blue items
indistinguishable from dark grey, and dark red looking exactly like dark brown ...

but can see they are clearly different under sunlight (? 6000K) ...

add some UV light to a very dimly lit room and see what happens to white and colours ...

An incandescent lamp, virtually by definition, has a Color Rendering Index (CRI) close to 100. This does not mean that an incandescent lamp is a perfect color rendering light source. It is not. It is very weak in blue, as anyone who has tried to sort out navy blues, royal blues and black under low levels of incandescent lighting. On the other hand, outdoor north sky daylight at 7500K is weak in red, so it isn't a "perfect" color rendering source either. Yet, it also has a CRI of 100 by definition.

http://www.gelighting.com/na/busines..._rendering.htm

Originally Posted by kzhan90n

... Trying to find the name of this effect.
The effect has to be related to the interaction of light and matter...
please help.

oh ... the term (name of this effect) you are looking for is metamerism ...

Originally Posted by kzhan90n

"Two pieces of clothing that seem to have matching color while inside the room, but don't have matching color when they are outside?"

This is why car painters always do colour matching in daylight.

Fluororescent lights are better than incandescent lights for true colour indoors.