As opposed to the electrolytic polishing where the subject material is made an anode and electro-chemically etched, chemical polishing does not employ electricity. The chemical polishing obtains glossy surfaces by submerging the specimen metals and alloys in acidic or alkaline solutions with salts added.
This polishing method is not suitable in precision surface finishing since it cannot remove relatively large concaves and convexes, and is more suitable in attaining glossy finishes on surfaces by removing fine imperfections left after pre-polishing.

Therefore, chemical polishing is used for aesthetic surface treating and pre-treatments for other surface finishes, and is a very effective treatment method in terms of production efficiency and costs.

Chemical polishing has the following characteristics.
(1) Since it does not use DC currents such as electrolytic polishing, there are no issues such as electrical current distribution uniformity, and complex shaped objects can be polished evenly with relative ease.
(2) Operation is easy, and many items can be processed at one time.
(3) Oxidation is removed and the entire metal surface will be exposed after the polishing process.

The mechanism of chemical polishing is not clearly elucidated but two of the theories are introduced here. The first is regarding a purpose of obtaining flattening and smooth brightening and generally uses high viscosity solutions. When the metal submerged in chemical polishing solution is viewed microscopically, convex sections initially begin to dissolve and metal ions start to be diffused. The metal ion diffusion occurs more freely on convex sections compared to the concave sections, thus the metal ion concentration is higher around the concave sections so the dissolution of the metal is hindered. As a result flattening and smooth brightening occurs.
The other is regarding alternately occurring passivated layer formation and dissolution, causing microscopic polishing. In this case not much flattening will occur.

Electrical energy was used to promote eluting of the metals since the electrolyte alone cannot elute the metal. With chemical polishing, it is necessary to elute the metal by chemical effects alone, therefore the polishing solutions used for chemical polishing are comprised of strong acids, strong alkali, and strong oxidants.

Industrially, the chemical polishing is used on aluminum and its alloys, copper and its alloys, and stainless steels. For the chemical polishing solutions, mainly phosphoric acid based solution such as sulfuric acid - phosphoric acid type, phosphoric acid - nitric acid type, phosphoric acid - nitric acid - sulfuric acid type are used.
In order for the chemical polishing to be effective, the subject metal surface needs to be of a consistent structure where the dissolution rate is uniform. Otherwise a good result cannot be expected.