All true mathematical definitions aside, we need to think of water as the least common denominator and the greatest factor in the success of any laundry program. Characteristics of pure water include no color, no taste, no suspended or dissolved solids, neutral pH, no calcium or magnesium (hardness) ions, no iron (particulate or dissolved) and little to no conductivity. By definition, it is fairly uninteresting material. Yet water unmistakably plays the most important function in a wash program.
Water provides a vehicle for mechanical action and heat transfer. It carries chemicals with various cleaning functions, and provides a means for connection between these chemicals and soils on the surface or embedded in the fabric. Water provides the medium for chemical action in the process of attracting soils and moving them away from fabric surfaces. It carries materials to chelate (form complexes) with hardness ions, and to suspend soils in solution so that they can be flushed free from fabric surfaces.
There are three basic water characteristics that a technician absolutely needs to check to assure best results from a chemical program. These are simple tests that are easily overlooked when performance falls. It is easy to focus on the chemical or machine programs, soil conditions, or personnel procedures. The bottom line is that when well functioning programs fall apart, one of the following common parameters has most probably changed. Water quality is the greatest factor in wash program performance.
Verify that expected temperatures are reached. Often overlooked are boiler issues, competition for domestic hot water at various times of the day, and programming errors which can result in inadequate temperatures. Reaction rates (and expected laundry outcomes) are directly dependent on temperature.
Overall or intermittent hardness are common contributors to poor results. Simply stated, detergents are designed to function with soft water and results, depending on the degree of hardness in the water, are proportional. Utilize simple tests for hardness. Test before and after wash fills, and test both hot and cold components. Test at all times of laundry operation. Changes resulting from equipment capability and system demands can result in wide variation between shifts, and even during a shift. Hard water can result in graying and overall dull linen. Actual cleaning capability of detergents is compromised by hard water and soil removal will be diminished.
Iron can enter a wash system as dissolved iron or particulate iron. While iron levels are typically reduced by half in standard softening systems, as little as 0.2 ppm dissolved iron can result in yellowing. Reduced stain removal and loss of brightening are the result of interaction of iron with bleaching agents. Sources of dissolved iron are typically from the water source.
Particulate iron can cause a range of discoloration ranging from yellow to orange/brown. Additionally, particulate iron can degrade cotton (cellulose) resulting in small holes at oxidation sites.
Particulate iron can be picked up in old pipes and disturbed water distribution systems. Look for problems when you see new building, remodeling or road construction. Particulate iron can remain in the system for a period of time depending on water flows. Water heaters are a good reservoir for particulate iron when systems experience loading.
Remember these very simple tests to identify major contributors in a well functioning laundry program.
Lab/R&D Manager Anderson Chemical Company