A mirror produces specular reflection; an incoming light ray bounces off in a single direction. A matte white surface produces diffuse reflection; incoming light rays reflect off in many directions (called scatter). A glossy white surface will produce some degree of both these effects.

I’ll add: although we naturally tend to think of white surfaces as being brighter than a mirror, reflected light in a mirror (or especially the reflection of the sun on a curved mirror-like surface) can be a zillion times brighter than a white surface.

Consider the sun as the white light source….

A white material only reflects a fraction of the white light of the sun as the sunlight strikes it. If is it a white cloth, there is a tremendous amount of random scattering of the light rays as it is reflected. Even a white egg, or a shiny Corvette only reflects a fraction of the total sunlight that strikes them, but more than a cloth napkin.

Logically, this makes sense, since you can gaze directly at a white napkin in bright sunlight, or even at a white Corvette in direct sunlight, whereas if you were to gaze at the sun, you would damage your retinas.

On the other hand, a mirror reflects the sunlight with a profoundly greater efficiency than a white “thing” or “object”.

However, simple, understandable, laws of physics dictates that even a mirror is not perfectly, 100% efficient in terms of reflecting light. Even when painting reflections in a mirror, they should be created just a tiny bit darker in value than the objects being reflected in it.

It is for this reason that when painting reflections of a scene in water, I always try to paint the reflections just a tad bit darker than the objects that created them.

That’s one reason that reflections of skies in water always appear darker than the sky, itself, if only a small amount. This is assuming, of course, that the goal of the painter is that of reality.;)

Funny you ask this question. I was about to ask if anyone has tried Tri-Art’s Liquid Mirror acrylic paint. They hype up it’s reflectivity quite a bit.

”It is an opaque pigment that can be described as metallic or platinum in colour…. it has superior reflective qualities than all other pigments, including Iridescents.”

The company already makes [/COLOR]iridescent paint in both [/COLOR]silver and pearl but claim that Liquid Mirror is markedly different. The exclusive shine properties of Liquid Mirror are attributed to the use of something called[/COLOR] bismuth oxychloride. The result, according to art guru [/COLOR]Marion Boddy-Evans of About.com, is:

“[/COLOR][/COLOR]a pale, very shiny, silver color. Like the shiny highlights on silver jewelry, the closest to what I visualize when I think ‘silver’ that I’ve come across in paint.”

But she admits that it can’t be truly appreciated in online photos or videos.[/COLOR]However at a whopping $20 average price for 60ml, I’m not prepared to pick up Liquid Mirror on faith alone.

What do you guys think?
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