How come wood or paint becomes reflective the finer the sanding process go?

Question

I’ve always wondered how a really opaque non reflective material becomes quite glossy and reflective with just really smooth sanding?

Like paint, as I buff it, it becomes real shiny and smooth, and reflective. Even wood when sanding up to 5000 grit or higher!

In:

Answer 1

The smoother a surface is the less diffrence there is in reflection of light. Its the same thing when you take a standard sheet of steel and grind/buff it down to be extremely smooth. Youll have almost a mirror because most of the light is now reflected in a uniform manner.