Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant

specular reflection Reflections on still water are an example of specular reflection. Specular reflection, or regular reflection, is the mirror-like reflection of waves, such as light Light or visible light is electromagnetic radiation within the portion of ...

(still limited by the

index of refraction In optics, the refractive index (also known as refraction index or index of refraction) of a material is a dimensionless number that describes how fast light Light or visible light is electromagnetic radiation within the portion of the el ...

of the material according to the

Fresnel equations The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be visual perception, percei ...

). In some materials (such as metals, glasses, black or transparent stones), polishing is also able to reduce

diffuse reflection Diffuse reflection is the reflectionReflection or reflexion may refer to: Philosophy * Self-reflection Science * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflec ...

to minimal values. When an unpolished surface is magnified thousands of times, it usually looks like a succession of mountains and valleys. By repeated abrasion, those "mountains" are worn down until they are flat or just small "hills." The process of polishing with

abrasive An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflect ...

s starts with a coarse

grain size Grain size (or particle size) is the diameter In geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of m ...

and gradually proceeds to the finer ones to efficiently flatten the surface imperfections and to obtain optimal results.

Mechanical properties

The strength of polished products can be higher than their rougher counterparts owing to the removal of

stress concentration are denser near the hole A stress concentration (also called a stress raiser or a stress riser) is a location in an object where the stress (mechanics), stress is significantly greater than the surrounding region. Stress concentrations occur when ...

s present in the rough surface. They take the form of corners and other defects which magnify the local stress beyond the inherent strength of the material.

Types

Metalworking

Other polishing processes include: *

Burnishing Burnishing may refer to: * Burnishing (metal), plastic deformation of a surface due to sliding contact with another object * Burnishing (pottery), pottery polishing treatment See also

* {{Disambiguation ...

Mass finishingMass finishing is a group of manufacturing Manufacturing is the Production (economics), production of goods through the use of Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. It is the essence of ...

Tumble finishing Tumble finishing, also known as tumbling or rumbling, is a technique for smoothing and polishing a rough surface on relatively small parts. In the field of metalworking Metalworking is the process of shaping and reshaping metal A metal (fro ...

Vibratory finishingVibratory finishing is a type of mass finishing manufacturing Manufacturing is the Production (economics), production of goods through the use of Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. ...

* Sodablasting

Woodworking

French polishing French polishing is a wood finishing A worker sprays a urethane finish onto a timber Wood finishing refers to the process of refining or protecting a wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and ...

Wood finishing A worker sprays a urethane finish onto a timber Wood finishing refers to the process of refining or protecting a wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees and other woody plants ...

Other

Chemical-mechanical polishing Chemical mechanical polishing (CMP) or planarization is a process of smoothing surfaces with the combination of chemical and mechanical forces. It can be thought of as a hybrid of chemical etching and free abrasive An abrasive is a material, ofte ...

, which is used in semiconductor fabrication *

Fabrication and testing of optical components Optical manufacturing and testing spans an enormous range of manufacturing procedures and optical test configurations. The manufacture of a conventional spherical lens A lens is a transmissive optical device that focuses or disperses a li ...

Flame polishing Fire polishing, also known as flame polishing, is a method of polishing Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflec ...

, a type of polishing used on glass and thermoplastics * Ultra-fine, abrasive paste polishing, polishing for soft or fragile work surfaces *

Vapor polishing Vapor polishing is a method of polishing Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the ind ...

, a method of polishing plastics to optical clarity

References

External links

4 Steps of Marble Polishing
{{wiktionary Decorative arts Grinding and lapping Industrial processes Wood finishing techniques Surface finishing