GEM-SET

Daily Digest Archive for August 19, 2003

Q: (Initially posted on August 14, 2003) FROM MENTEE ALEXIS K. IN VA
How does multicolor, glittery enamel paint function? For example, in car
paint, the color of the car might look one sparkly color and then from
another angle look like another color. Also in nail polish, each angle
reflects a different color. I noticed that you can never see more then one
color at a time. Why is that? Also is there a relationship between
multicolor, sparkly enamel pain and holograms because they too look
different from different angles and you can never see more than one thing at
the same time. What is the process for making holograms and what is the
process for making enamel paint that all this color and image diversity
occurs? Is this a visual trick that fools the mind, or is there really
different stuff that the eye is perceiving or both (or something else). I
can't figure it out by looking at the paint and holograms but am fascinated
with this. My sister brought home a dead beetle the other day and the
underbelly was exactly like a multicolor nail polish I have. Looking at the
beetle from different angles did exactly the same thing that my nail polish
did. Do you suppose that the idea for the paint came from nature and is the
chemistry the same for the paint as it is for the beetle (or similar)? This
is a lot but it is an interesting mystery to me and I could use help
figuring it out.

August 19, 2003
A: FROM MENTOR JOAN LUSK IN RI
What a lot of really interesting questions! I found this site:

http://www.colorshift.com/index.phtml?s=Technical which seems to be a company that makes the paint for Ford cars. They have an on-line color simulator showing a car with various color-shifting paints ("Officer, the car that hit me was red coming at me but blue while it sped away!") And a diagram "Color by Physics" showing the different wavelengths of light reflected at different angles. The technical documents posted on the site go into more details of the pigments and reflective aluminum in the paint - but a lot of the details must be proprietary information.

Holography is something different.
http://members.aol.com/gakall/holopg.html I think the color changes you mention must be "multiple channel holograms" - defined on this site. Frankly I can't explain but I hope the site will help you! This site http://www.abdn.ac.uk/physics/px2010/int.pdf says that the iridescent colors on beetles and feathers are forms by interference between light waves and tells you a lot about the physics involved.

What remains for you is to put all the information together - what exactly are the similarities and differences, and what objects get their color by which methods. I bet most of us wearing nail polish didn't know we were using that much physics for decoration!

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August 18, 2003
A: FROM MENTOR .SALLY RAMSDELLIN KY
Regarding your questions about paint which appears to change color, there
are several technologies. The most common is to use flakes of mica or
metal (such as aluminum) in the paint which act as prisms and reflect light
differently to cause the effect. Another method controls the density of the
paint which is like 1-2-3 Jello and separates on its own into different
layers which reflect differently.

Holography is totally different. It is the projection of a stereo image
onto a translucent medium, so you see the image in 3D based on the
convergence within the medium.

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