Before any restoration or appliance is placed permanently in the mouth it should be highly polished. In spite of all the care taken during processing, many restorations and prostheses usually require further trimming, smoothing and finally polishing. A rough or unpolished surface may: Be uncomfortable to the patient, Cause food and other debris cling to it and makes it unhygienic, Lead to tarnish and corrosion. Abrasion occurs when a hard, rough surface slides along a softer surface and cuts a series of grooves. Polishing is the production of a smooth mirror like surface without much loss of any external form. If the particle size of an abrasive is reduced sufficiently, the scratches become extremely fine and may disappear entirely. The surface then acquires a smooth shiny layer known as a polish.The polishing agents remove material from the surface molecule by molecule. In the process fine scratches and irregularities are filled in by powdered particulates being removed from the surface. The microcrystalline layer is referred to as polish layer or Beilby layer. A polishing agent is employed only after an abrasive obliterates or eliminates most of the fine scratches, leaving a smooth finish.