Rough surfaces look dull. Dry surfaces
are pale and washed out. Sealed surfaces can be rich, and polished surfaces are
deep and shiny. We all know this, but what is going on? Light reflects off
surfaces, and what an object looks like depends upon the material's surface
characteristics. Some of the light is reflected, some is scattered and the rest
is absorbed, so we see different things depending upon how much light is
reflected from the surface and how much is scattered. The Brisbane coloured concrete depends upon what is absorbed. A highly polished mirror reflects most of the
light in one direction. Almost all of the light rays are reflected in a
parallel orientation and nearly none are scattered. Because the light is
reflected without scattering, the image is clear and in focus. This is called
"specular reflection," and the term often is used to describe the
highlight visible on a brightly lit object and the glare seen from light
shining on a very shiny surface. Rough, translucent or transparent objects
scatter most of the incoming light in a "diffuse reflection," with
little or no glare from specular reflection.
When concrete is wet, sealed or highly
polished, there is more specular reflection than diffuse reflection. At certain
viewing angles all we see is glare or the image of the light that's
illuminating the surface. At other angles, not in line with the path of the
reflected light rays, we don't see any glare - all that's visible is the Brisbane coloured concrete of the surface. When concrete is dry or is not polished, almost all of
the light is scattered in diffuse reflection and the surface seems pale, washed
out or dull. That's because there's no focused reflection of the light source.
The incoming light is scattered and overwhelms the reflected coloured concrete.
The net effect is that the surface appears light, dull and washed out no matter
what angle the concrete is viewed from. Sealers can fill in microscopic surface
roughness, reducing the amount of diffuse reflection and increasing the
specular reflection. This is why concrete that's sealed or is wet appears
darker and richer in coloured concrete. It also explains why shiny surfaces
have glare.
With shiny surfaces, more of the white
light from an illumination source reflects off the object. What diffuse
reflection occurs shows us the coloured concrete of the object. All the light
is affected by the coloured concrete of the object, but the intensity of the
specular reflection on smooth, wet or shiny surfaces overwhelms the diffuse
portion. A surface fixed with a matte finish has some specular reflection that
shows the coloured concrete and some diffuse reflection. Generally, the
glossier the surface, the deeper and richer the coloured concrete appears.
Conversely, with a flatter and less shiny surface, the coloured concrete tends
to look more washed out and dull. Looking at a matte and reflexive surface of
the very same color, the matte surface has enough dispersed white light to
weaken the reflected coloured concrete, showing up additional washed out and
lifeless.
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