Holchem Insights: Warewashing

Blog | 21 July 2017

In the second of a series on warewashing (encompasses dishwashing, utensil washing, cutlery washing and glass washing) we look at a number of important elements of the process.  Our technical and sales teams are constantly working with our customers to ensure that their warewashing is to the highest standard and their teams are trained to ensure a successful operation.   Here’s some of the most common topics that we advise on:

  • Dishwashing machines may be general in their ability to cope with different items and soils; however, it is common that glass washing machines tend to be specific and only used for glass washing. Some machines have user selectable programmes to best optimise the cleaning programme to the item being cleaned and the level of soiling.
  • The quality of water used to feed a washing machine has a significant impact on the operating costs of the machine and on the appearance of the washed item.  Hard water salts in the water supply need to be controlled by partial removal, complete removal or by utilising detergent and rinse aid chemistry.  With poor control, washed items may show water scale deposits, seen as a dull and lacking sparkle finish to in the extreme white deposits. In addition, water scale build-up can cause damage to the dishwasher and impair its performance. Water treatment can involve water softening, partial de-mineralisation or reverse osmosis depending on the original water quality and the required standard of finish.
  • Warewashing because of the enclosed nature of the cleaning cycle can utilise higher alkalinity detergents.  This use of high cleaning energy from both the detergent and the higher temperatures enables most soils to be removed with the lower physical energy from sprays compared to the scrubbing action with hand washing.  Most warewash detergents are alkaline based with wetting systems to ensure soil penetration and suspension and water hardness control systems to reduce or stop the deposit of hard water salts.
  • Rinse aids alter the surface tension of the water used for the final rinse of the item. This ensures that the washed item sheds the water as a continuous film rather than allowing drops of water to sit on the surface and subsequently created a dull or spotted appearance.
  • Detergents are generally liquid formulations that are dosed into the main wash tank to give a 0.2 to 0.5 % v/v solution. The product is dosed using a peristaltic pump and controlled either by a timed dose or by conductivity of the detergent solution. The choice of control method will be made based on the type of washing machine. For instance, with a single tank washer a timed dose is added to the wash tank during each wash cycle of the machine. This dose makes up the fresh water addition that is added each cycle. With a conveyor type machine conductivity is often used as the preferred method of detergent control.
  • Rinse aid is commonly added to the final rinse step of the wash whether this is in a single tank or conveyor machine.