Expert Guide to Laundry Production: The Washing Phase
The washing section is the heart of every laundry! Quality without question starts here. Aided by correct soil classification and load make up in the soil sorting section. The goals and objectives of the washing section include:
- Quality
All washed items should be hygienically clean and stain free with a minimum percentage of rewash. - Production
The washing section should set the highest standards of output with the washroom equipment available with established quality standards. - Productivity
Maximum production should be achieved with the minimum amount of labor required based on available equipment. - Other costs
Water, sewer, energy, chemicals, etc should be as low as possible based on available equipment and quality standards. - Textile life
Wash formulas must be monitored to ensure excessive textile degradation and tensile strength loss do not occur during the wash process.
To achieve these goals and establish meaningful standards in the washing section, we must understand and apply certain basic processes.
The wash cycle: 6 basic steps!
The washing section launders textiles to make them hygienically clean and stain free. As near as new as possible! The sequence of operations in the laundering process consist of 6 basic steps including flush, break, suds, bleach, rinse and sour plus starching if required. A drain and fill follow each step.
The flush step is an optional clear water rinse at high water level, typically for 1 to 3 minutes at a temp of 40 degrees C or less. By removing loose debris and loosening bound soil, this reduces the amount of chemicals needed later. The flush also helps to remove volatile or flammable soils and reduces stains from blood, proteins, printer ink etc. Some formulas provide a cold flush first then a hot flush to raise the temperature for the next step. Chemicals may or may not be added here depending on the load classification.
The Break step is the most important chemical step for effective and efficient removal of soil. Following the flush or beginning the washing cycle in formulas the do not require a flush. With a higher temperature and low to medium water levels concentrating the chemicals and maximising the mechanical action to enable surfactants and alkalis to work on the soil removal. Time ranges from 5 to 20 minutes.
The Suds or carryover step employs the residual chemicals retained by saturated textiles after the water from the break is drained. The residual chemicals become depleted, in some cases, additional chemicals must be added. The suds step also runs at a medium water level. Time ranges from 5 to 10 minutes. In formulas for very heavy soil, several suds’ steps may be required.
The Bleach step is primarily on white- or pastel-colored textiles at a medium water level. Its purpose is to remove stains, enhance whiteness and assist in hygienic cleaning. To ensure the bleach step is effective and to avoid fabric damage, it is essential to accurately control bleach quantity and strength, PH level, temperature and time. It is costly to have any bleach carryover. Bleach carryover damages the fibers and causes fabric damage from heat in tumbling dryers and ironers. This degradation is a prime source of lint.
The Rinse steps are run at higher water levels for maximum dilution, the elimination of residual chemicals and removal of any remaining suspended soil. Rinses run from 1 to 3 minutes, just long enough for the fresh water to thoroughly saturate the fabrics. Sufficient rinses should be used to ensure the final rinse is equal in chemistry and clarity to that of the incoming water supply. If this is not achieved serious problems can occur and quality will be adversely affected.
The Sour step is the final step of the laundering process, is run at low water level. The sour is a mild acid which neutralizes excessive residual alkali. The purpose of this is to reduce the PH of the textiles to neutral. Sour should not be used in place of rinses. Other chemistry such as softeners, mildewcides and starches etc may be used in the final treatment of textiles depending on classification.
The development of a precise wash formula is completed in conjunction with the laundry management and a trained chemical technician. Wash formulas will vary greatly depending on the type of textiles being processed. These variables include fabric, fiber content, color, type and degree of soil, finishing process etc.
