Question

why does a polished shoe appears to be shiny than before it had been polished? 

Answer 1

A dusty shoe does not shine. Because, the dust particles and rough surface (scratches and scuffs) scatter the light in all directions. The reflected light goes in all directions rather than falling in our eyes as a beam. So the shoe appears dull. Shoe polish is made of colored mixture of waxes. It can be liquid or solid wax. Let us look at how the solid (paste) wax works.

First we clean the dry shoe with a cloth to remove dust. Then we use a brush to apply polish on the shoe. During the process of rubbing, some wax melts (due to friction and heat generated) and fills in to the scratches (cuts, cracks) and scuffs (crevasses) on the surface. We wait a few minutes for the wax to dry. Now, the shoe appears like matt or dull finish, as it is not smooth yet.

Now, we take a smooth cloth and rub the shoe fast and pressing softly. The polish melts again due to friction and smooths the surface evenly. Now the surface becomes reflective and shining. The shoe appears glossy because a beam of light is reflected in to our eyes and very little is scattered in other directions.