The following description of "Hard" water was used as part of presentation to a company describing the benefits of treating their incoming water from a well, used to clean parts prior to painting and plating. Water Supply What is considered normally good, mineral laden, drinking water is not always good process water. All ground water supplies contain a a certain amount of dissolved minerals. In those areas where the ground water is predominantly limestone, rain water dissolves significant amounts of calcium and magnesium carbonate. This is caused by the fact that the rain water starts out rela- tively pure, and on it's way through the air, dissolves large quantities of carbon dioxide from the air. Carbon dioxide gas, when dissolved in water forms carbonic acid and causes the rain water to be slightly acidic (did you ever hear of putting a rusty nail in Coca-Cola?). This "acidity" is then neutralized as the rain filters through the limestone changing the water from slightly "acidic" to slightly "alkaline". Because most waters are not completely alkaline, they contain a mixture of carbonates and partially neutralized carbonic acid known as bicarbonates. Over the years , these particular dissolved minerals have become known by the trouble they cause. Calcium and magnesium, because they retard the action of soaps and detergents, got the name "hardness". They leave their evidence in wasted cleaners, soap film and insoluble sludge. Carbonates and bicarbonate, because they are the opposite of acids, got the name "alkalinity". When found with calcium and magnesium, alkalinity forms a tightly adherent sludge called "hardness scale" that is found in most pipes, water heaters, untreated boilers, cooling towers and industrial washers. The most common form of treatment is softening, where "soft" sodium carbonates are exchanged for the "hard" calcium and magne- sium carbonates. This however does not reduce the total amount of material that is dissolved in the water. An alternate method, known as "dealkalization", takes the process one step further where "soft" hydrogen carbonates are exchanged for the "hard" calcium and magnesium carbonates. The hydrogen carbonates, also known as carbonic acid, (carbon dioxide dissolved in water) are then removed from the water by passing through an air stripper. The resulting water is substantially reduced in both hardness andalkalinity. The water is then close in comparison to typical fresh lake, brook or rain water. This process is about half the capital cost of D.I. (deionized) water and substantially less expensive to operate. It provides many production benefits by improving chemical ability to clean, thereby decreasing chemical consumption and cost. It would sig- nificantly reduce sludging and scaling in all stages of the washer. Dave Wright - Texo Corporation