Wash your chemical blues away with Calgon.

In 1933, Calgon Inc. of Pittsburgh introduced its flagship product, Calgon. The name was derived from the phrase "calcium gone," a description of what the product was designed to do, which was soften water. Hard water has a high content of dissolved minerals, mostly salts of calcium and magnesium and problems ensue when the concentration is greater than about 120 milligrams per litre. Unlike the sodium salts of fatty acids that are the basis of soaps, hard water's calcium and magnesium salts are insoluble, resulting in the classic bathtub ring. Although detergents do not form precipitates with hard water minerals, they do form soluble complexes that reduce cleaning efficacy.

Another problem is the conversion of dissolved calcium and magnesium bicarbonate to insoluble calcium and magnesium carbonate when the water is heated. These insoluble salts form a scale that can clog pipes, deposit on clothes and, in theory, break down washing machines. Softeners added to water either cause the calcium and magnesium to precipitate as salts that are easily rinsed away or sequester the calcium and magnesium ions as soluble complexes preventing them from reacting with soap or forming deposits.

The original version of Calgon consisted of sodium hexametaphosphate, a chemical that would sequester calcium--it appeared to be gone! Advertising emphasized the ability of Calgon water softener to improve the appearance of laundry. When television invaded America, Calgon was ready with clever ads. In a classic, a lady asks an Asian laundry shop owner how he gets the shirts so clean. "Ancient Chinese secret," he responds. The 'secret' is exposed when the owner's wife shouts, "We need more Calgon!"

By this time the water softener had been joined by a line of Calgon bath salts and bath oils. These also contained sodium hexametaphosphate to soften the water and incorporated magnesium sulphate, or Epsom salts. This combo gives the water a more slippery feel and softens calloused skin. Calgon bath oils were popular, consisting of coconut oil that would leave a silky deposit on the skin. Ingenious advertising slogans promoted these products, including: "Love the skin you're in" and "Lose yourself in luxury."

In 1968, Calgon was acquired by Merck. Eventually, it was broken up and sold to a number of companies along with the right to use the name Calgon. Today, there are various bath products, body mists, creams and beauty bars that feature the Calgon brand. Water softeners are also still with us, although the original formulation has been altered because of the environmental consequences of phosphate. Since phosphorus is an essential plant nutrient, an abundance of phosphates in natural waters can lead to excessive growth of plants and algae, which decompose and use up some of the water's dissolved oxygen. This can have dramatic effects on aquatic life.

Several versions of Calgon water softeners are now available, conforming to local laws about how much phosphate content is allowed. In most cases the active ingredients are sodium sesquicarbonate and various polymers that fall under the umbrella of "polycarboxylates." These are either polymers of acrylic acid or copolymers of acrylic and maleic acids. They do the same job as the phosphates, namely bind minerals in solution but without the environmental consequences of the phosphates. The Canadian version still contains a small amount of pentasodium triphosphate, while the American product uses a mix of sodium sesquicarbonate and sodium citrate--yet another polycarboxylate--to soften water. Advertising emphasizes that less detergent is needed if the water is softened because the complexed dissolved minerals do not interfere with the detergent.

In Europe, Calgon's emphasis is not on softening water but the product's role as a saviour for washing machines. The claim is that scale buildup inside machines shortens lifespan, and the addition of a water softener to each load of laundry can keep the machines from a premature death. The British consumer group Which? addressed this claim by simulating three years worth of washing. It found that there was a decrease in the build-up of scum but there was no difference in the way the machine performed--with or without Calgon. Which? researchers calculated that the amount of money spent by adding a water softener to every load was enough to buy a new machine when needed, even if the scale deposits shortened the life of a machine. Many consumers were irritated, thinking that they may have been throwing their money down the drain. Calgon could have advised them to take a comforting bath using Calgon bath salts and bath beads.

Joe Schwarcz is the director of McGill University's Office for Science and Society. Read his blog at chemicallyspeaking.com.