Quote:

Quote:

"When the light hits it and refracts, it shows off the vehicle's architectural form beautifully."



I would think Mr. Webb should be quite embarrassed that as GM's color designer he has screwed up "reflect" and "refract"



Refraction is probably the right term...

Refraction = The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different optical density.

This gives cause to how the paint job disperses the colors that are picked up by our eyes when the light hits the surface. You have seen how light reacts when it hits a prism and is refracted as the three primary colors.

In a way refraction is the principle behind 'mystic' paint jobs - which give off a totally different color 'depending on how the light strikes it". If you could paint a car with zillions of microscopic prisms, the light refracting off that paint job would give the car a spectrum of colors depending on how the light hits it.

On my GTA for example, I went with a single light sand color and a multiple layer polyurathane gloss coat. Because of this combination the light refracting off the body does highlight the architecture of the body because the refraction of the one color on different parts of the body give off a different color to your eyes when you see it in sunlight. The lower aero effects are at one angle to the ground. They reflect a darker sand color - which compliments the different sand color of the lower portion of the door panels below the side moldings. And yet another color of sand brown is reflected from the various angles of the body above the molding line. So from a one color paint job I end up with a car of ten shades of sand brown - depending on how the sun hits or refracts against those angles.

WHEREAS..

Reflection = The act of reflecting or the state of being reflected or something, such as light, radiant heat, sound, or an image, that is reflected.

So in this case the reflection can be better described as the ability of the surface to bounce back to your eyes an inverse of the entity being bounced off it.

A ball reflects off a wall, your image reflects off a mirror, your image reflects off a highly shiny and glossy paint job.

And the degree of reflection is something that can be scientifically measured. A mirror used for the Hubble telescope probably rates the nearest to perfection at 99.99% reflection ( because it has the highest degree of perfection and the lowest possible amount of defects ).

A normal commercial house mirror probably rates at 90% to 95% true reflection, with variable like glass compared to plastic, and true silver compared to artificial silver explain the wide difference

A car paint job could probably run from 5% to 10% for a satin flat paint job, to about 50% to 70% for a car paint job depending on variables like the color of the paint and the quality of the finish to the outer surface.

Aussie Driver's mirror black Miata for example would equal a 70% reflection, whereas a MAACO stock paint job probably only rates 50% ( during its first month and then it degrades from then on ). My red McLaren probably rates about a 60% - which means I have a lot of room for improving the shine or reflection of light from my car, but only up to the point that the red paint will let me. Black is obviously a better color to create a higher degree of reflection from.

So given all these facts so far.. you can see that a paint job could have a high degree of refraction while at the same time it has a low degree of reflection. For example, you don't get a very clear image of yourself reflected back at you when you put your face up to a 'mystic' paint job.

And as for the satin flat paint jobs... they tend to have both a low degree of refraction and a low degree of reflection. But as a paint job they may have a high degree of 'absorbtion' - in that they absorb the light being bounced off them and bounce back nothing. The ultimate version of 'absorbtion' in paint would probably be the paint jobs that they slap on Stealth Fighters and Bombers. Not only does their paint absorb light, but as well it absorbs radio spectrum (RF) waves and doesn't bounce anything back.

Which reminds me of the time someone was selling 'genuine' Stealth Fighter/Bomber' paint in a small classified ad in Popular Mechanics magazine. The guy was selling it as a way to beat speeding tickets - because once it was painted on the front of your car the radar guns signal would be absorbed and not bounced back to the officer with the handheld radar gun. The FBI and security agencies quickly investigated it and seized all the paint from the guy - and then went and raided and seized all the paint that had been sold to the 'customers'. The paint is a classified / top secret thing and that is why they did not want it falling into the public's hands ( which in turn might have been spies ).

I always thought that was a neat little story that many of our fellow painters might never have heard of but it did sort of tie in to this discussion about refraction, absorbtion and reflection.

Tee hee... I won't bother raising the point about

Diffraction - which is the change in the directions and intensities of a group of waves after passing by an obstacle or through an aperture whose size is approximately the same as the wavelength of the waves.

Whoops I guess I just did...

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Last edited by Marq; 09/23/07 12:50 PM.