# Why does a black polished shoe sign even though black absorbs light

Why is this? Im totally lost

When light falls upon a surface, one of three things can happen to it: it can be absorbed, it can be reflected, or it can be scattered. Scattering is what happens on a “white” surface. If you shine a narrow beam of light onto it, the light is scattered back in all directions. Reflection is what happens on a “shiny” surface such as a mirror - the reflected beam is still narrow, just travelling in a different direction.

Now, scattering and reflection are two independent parameters - that is, it’s possible to have one without the other. A white piece of paper, as I said, has a lot of scattering, very little absorption, and very little reflection. Polished white marble has a lot of scattering, a fair amount of reflection and very little absorption. A piece of coal has a lot of abosorption and very little scattering or reflection. And a black polished shoe has a lot of absorption, a fair amount of reflection, and very little scattering.

Acutally, they are not completely independent parameters - the three must add up to one. Of the light falling on a black shoe, maybe 10% will reflect, 1% will scatter and 89% will be absorbed. (That’s a WAG)

But the coeffecient of absrption for a black substance is very very close to 1 if not one , and in my polishe black shoes belive it or not I can see my face in reflection

Are you using wax shoe polish? You could be seeing your reflection in the wax surface. Once light penertates and hits the black particles, it gets absorbed.

Reflection of light depends on the angle it hits the surface. Light that hits at a shallow grazing angle tends to be reflected rather than absorbed.

Polishing something smooth makes it more reflective. On a rough surface, light coming it a a shallow angle to the marcoscopic surface, hits a bunch of pits and hills on a microscopic scale, so less actually hits at a shallow angle. Polishing removes the hills and pits.

The light that arrives at the shoe’s surface will be reflected, refracted or transmitted (in this case, absorbed).

There are two classes of reflection:

[ul]
[li]diffuse reflection - occurs when irregularities on the reflective surface are large in comparison to the wavelength of reflected wave; light reflected this way is visible in all directions;[/li][li]specular reflection - occurs when irregularities on the reflective surface are small in comparison to the wavelength of reflected wave; a narrow beam of light hitting a specular surface is reflected in one direction only.[/li][/ul]

Reflection from your polished shoe is intermediate.

The intensity of the reflected or refracted rays varies with the angle of incidence, as I believe starfish noted.

So the nature of the surface and not the color of the object is what determines what sort of reflection you see.

How do you know that? It’s not easy to measure absorption coefficient. If something is black, it just means that the diffuse reflection is very very close to zero. It can still have, say, 80% absorption and 20% specular reflection. (That would be about right for a piece of glass with the back surface painted black.)

the black shoe polish has a shine to it
this shine is what is responsible for reflecting the light

Zub’s right. Want to test it? Get a brand new pair of patent leather black shoes. See? You cutie-pie you, you look lovely in that reflection.

Now get a brand new pair of black suede shoes. Hmmm…a whole lotta nuttin reflected, right? It’s not the black color itself, it’s the wax coating that is acting as a mirror.

When you sit at the table- or counter- at the much MUCH beloved Empire Diner on 10th Ave in NYC, you can see yourself- and a lot of light reflections- in the black glass used for the tabletops there. God, can they make a nice omlette.

Cartooniverse

This is a later-in-to-the-evening post after a few drinks, so there my be some huge hole in my thought that I’m not appreciating. IOW, a post from la-la land (Hey! I’ve been on duty out scoutin’ locations for the upcoming Houston DopeFest). The thought occurs that if black objects reflected no light, how would we know they are there? Bump into’em, I guess?

There are two types of black, black paint, and looking down into a deep dark well. One is a black surface, one is a black cavity. Obviously the shoe is a black surface, which can also have other reflective attributes (i.e. black patent leather vs black suede). A cavity has no reflective properties, it reflects no light because it is a void. It is as black as you can get.
I personally did some cool artworks using curved mirrors, but instead of silvered, the back surface is black. Then I point them at a dark cavity. You get both blacks. It’s like looking into a black hole. You can see it’s a black surface, but it’s reflecting a void. People freak when they see em.