There is a limit beyond which polishing of a surface increase rather than decrease frictional resistance. Explain why

Dear student

Friction arises due to molecular adhesion, more precisely due to electrostatic forces. The roughness of surface plays a role when the bumps("hills" and "valleys") are big enough to lock the surfaces each other and avoid motion. But when the surfaces are further polished, the bumps become even and the surface area of contact increases, the surface molecules are able to come closer to each other, as a result the electrostatic forces(adhesion) between the atoms of the surfaces increases.
Rub your palm on a smooth mirror surface, you will feel the adhesion.
 
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Arun (askIITians forum expert)