Reduce Rewash Through Proper Sorting, Formulas, Stain Treatment (Part 3 of 5)

What measures can a laundry manager take to reduce the percentage of stain rewash found in their operation? How can they differentiate stains from soils? What do you consider an acceptable reject/rewash rate to be?TECHNICAL SUPPORT: Jim Mitchell, principal technical support specialist, is a 26-year Ecolab veteran. He's currently its OPL lead in providing technical support to field associates. He edits Institutional Technical Digest, a monthly publication reaching 2,800 employees.
We could talk for hours on end about the factors contributing to high rewash rates. But briefly consider this. Take the time and do an in-depth analysis of your laundry operation. Remember the five basic factors that contribute to clean linen:

  • Time.
  • Temperature.
  • Chemical action.
  • Mechanical action.
  • Procedures.

Deficiencies in any of these factors can lead to a high reject rate. If possible, contact your chemical representative for assistance.Time – Contact time in various cycles of the wash formula is very important. Sufficient pre-flushes will help reduce water-soluble soils. Sufficient post-rinses will help evacuate residual soils as well as chemicals from linen.
The proper contact time with chemicals is vital. Solvents, alkali, surfactants, chlorine, hydrogen peroxide, sours, etc., all require sufficient time to perform. An enzyme detergent may perform best in a longer suds bath (12-15 minutes) compared to a built alkaline detergent (8-10 minutes). Any deficiencies in time can lead to rejects.Temperature – Proper formula temperatures are also important. Pre-flush temperatures that are too high can set some soils. Temperatures that are too low in your chemical cycles can lead to insufficient soil removal.
Solvents, alkali, surfactants, chlorine, hydrogen peroxide, sours, etc., all require specific temperature ranges to perform properly.
Also, don’t make an assumption that your formula temperatures are set properly for the chemicals. New chemistry on the market may require a temperature completely different from the chemistry that is in use. When making a change in chemical suppliers or simply in the chemicals themselves, adjustments in formula temperatures may have to be made.
A good example of this would be changing your operation from chlorine bleach to oxygen bleach without adjusting cycle temperatures. Oxygen bleaches require a higher temperature to provide optimum performance compared to chlorine.Chemical action – The correct chemical choice for the soil and linen types you typically wash is critical. Different classifications of soil may require specific chemicals for removal. Using chlorine bleach in a healthcare laundry, for example, is preferred by most managers. However, if the facility uses a hand-wash product that’s chlorhexidine gluconate-based, using chlorine bleach on these soils is not a good idea, as permanent stains could be the end result. Oxygen bleach would be the best choice here.
Using a solvent in the prewash of heavily soiled industrial rags (grease and oil) may perform better than an alkali break.
Using an enzyme detergent alone on healthcare diapers and pads may do a good job removing the protein-based soils but a poor job removing any soils caused by medicines, food supplements or vitamins given to the residents. Adjustments will have to be made to improve chemical action.
Proper parts-per-million (ppm) titrations and pH levels are critical for chemical performance. Not only do the dilution rates have to be set according to soil classification and level, the water conditions should also be considered. Poor water conditions may require higher ppms and/or the addition of a “water conditioning” product.Mechanical action – Many years ago, the action of beating clothes against a rock produced “mechanical action.” This same action was produced by pushing clothes up and down on a “scrub board.” Mechanical action is necessary to help remove soils from linen.
Mechanical action is created in the laundry machine by three factors: the rotation of the wheel (drum or basket), the amount of water in the wheel and the amount of linen added to the water.
A laundry machine with a water level that is set too low and/or that is overloaded with linen will create poor mechanical action. This scenario will also result in a poor distribution of chemicals as well as poor flushing and rinsing.
A machine with water levels that are set too high also causes problems. Not only does excess water dilute the cleaning chemicals (causing poor results), it also has a tendency to cause linen to float in the wheel, producing poor mechanical action.Procedures – This is the forgotten factor. Employees who overload the washer and choose the wrong wash formula on the laundry machine will create result issues.
Employees who mix heavily soiled linen with lightly soiled linen will create result issues.
Employees who choose the wrong formula on the chemical dispensing system will create result issues.
If your operation has a chemical dispensing system that does not include an “empty product alert” device and employees fail to change empty pails, this will also create result issues.
Employees are a big factor in successful soil removal. Proper training and follow-up is necessary.
One easy way to differentiate stains from soils is odor. If linens smell like grease or oil, they are not clean. If healthcare linens smell like feces or urine, they are not clean. If personal linens smell like body odor, perfume or cigarette smoke, they are not clean. Remove the soil first, then deal with stains.
There are a number of generic classifications of soils: water-soluble, alkaline-soluble, acid-soluble, enzyme-soluble, solvent-soluble, insoluble and others.
If you have problems with a particular stain/soil, you may be able to identify what classification of soil it is by setting up a series of chemical soak solutions in some type of soak tank, or in your laundry machine if it can be programmed for a soak cycle.
You can also process several pounds of the affected linen in your laundry machine one load at a time with a solution of alkali, enzyme, solvent, acid, etc. Whichever chemical removes the soil should then be applied to your operation. If none of these chemicals remove the soil, it may be insoluble. If that’s the case, oxidize the stain with a bleaching agent.What do you consider an acceptable reject/rewash rate to be?
We could debate for hours on end about what is considered an acceptable reject/rewash rate. But if I were to give a good, generic answer, it would be:Hospitality

  • Budget, 2-3%.
  • Full-service, 3-4%.
  • Luxury/resort, 4-5%.

Nursing Home

  • With disposable diapers/pads, 6-8%.
  • With washable diapers/pads, 8-10%.


  • Wide range here because of many variables, 4-10%.


  • With no hospitality linens, 8-10%.


  • Wide range here because of many variables, 6-10%.


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