Calgon was introduced in 1933 as a powdered, chemical water softener. Its chemical name is sodium hexametaphosphate. The name "Calgon" is derived from "calcium gone" due to the chemical's ability to combine with calcium, a primary cause of hard water and limescale. The product was later marketed as different brands for use in cleaning and for bathing. The different Calgon brands were eventually sold off to other companies. The water softener branch was sold to Reckitt Benckiser, bath and beauty products were sold to Coty Inc., and Calgon Water Management was sold to English China Clays Ltd. The way these brands were marketed and sold indicate the variety of uses for Calgon.

Washing Machine Cleaner

Because of its water-softening properties, people use Calgon products to remove and prevent hard water buildup in washing machines. The Calgon-branded washing machine product comes in powder, tablet and gel formulas. It is sold and marketed throughout Europe by Reckitt Benckiser.

Teeth Whitener

Though not marketed as "Calgon" in this case, the chemical sodium hexametaphosphate is used as a whitening ingredient in some toothpastes, such as Crest Vivid White. It is shown to remove existing stains and help prevent new stains from forming.

Clay Dispersing Agent

One of the lesser-known uses for Calgon is as a thinning or dispersing agent in a ceramic technique using a fine particle slip. In ceramics, slip is a thinned mixture of clay and water. The chemical properties of sodium hexametaphosphate break down clay, causing the heavy particles in the slip to settle to the bottom of the container. This allows the fine particles to be siphoned off and applied to a greenware ceramic surface.

Water Softener

Calgon was originally, and still is, used as a water softener, particularly in preparing water for dyeing processes. Minerals in hard water can affect the purity and vividness of fabric dye.