Dealing with pH values in cleaning


19.02.2020

In cleaning, a pH value indicates whether a cleaning solution is acidic, neutral or alkaline (basic).

What does “pH” stand for?
The abbreviation pH (Latin Pondus Hydrogenii) translates as quantity of hydrogen. The pH value therefore indicates the concentration of hydrogen ions (protons) in a solution.

Many protons = acidic
Few protons = alkaline/basic

What does the pH scale indicate?
pH values range from 0 to 14.

Value of 7 = neutral (equivalent to pure water)
Value below 7 = acidic
Value above 7 = alkaline/basic

How do you determine the pH value?
The easiest way to measure the pH value of a cleaning solution is to use a pH test strip (indicator strip). All you have to do is hold the pH strip in the cleaning solution for a few seconds, ensuring all test fields come into contact with the solution. The test strip will then show the pH value measured.

Why is the pH value measured/specified?
The pH value shows what the cleaning product is suitable for. Due to their ability to dissolve limescale, acidic cleaning products are generally used for cleaning sanitary areas and toilets, while alkaline or neutral cleaning products are ideal for cleaning kitchens and tableware. Particular care must be taken when cleaning floors, to avoid using cleaning products that are too acidic or too alkaline. While strongly acidic cleaning products can damage certain types of floors (e.g. limestone), strongly alkaline cleaners are problematic for certain coloured floor coverings or linoleum.

Basic rules:

  • Most mineral-based dirt (limescale, urine scale, etc.) can be dissolved using acidic cleaning agents.
  • Organic grease and oils can be transformed into a water-soluble form by alkaline cleaning agents (depending on the degree of alkalinity) and then removed.

HOWEVER: There are also acidic and neutral cleaning products that are great for removing organic dirt – namely those that contain surfactants (washing-active substances). Most alkaline cleaning agents contain surfactants and/or solvents, which strongly support the cleaning performance. These are used, for example, in places where highly alkaline cleaning agents would be harmful.

An example of alkalis vs. surfactants can be seen in personal hygiene. Greasy hair it is not washed with a highly alkaline shampoo, but with a relatively pH-neutral shampoo. This is because excessive alkalinity would harm the skin (scalp and hands).

The following table provides an overview of the three pH ranges:

Acidic cleaners Neutral cleaners Alkaline cleaners
WC cleaners All-purpose cleaners Kitchen cleaners
Sanitary maintenance cleaner Alcohol-based cleaners Basic PVC cleaners
Limescale removers Deodorizing cleaner Oven and barbecue cleaners
Cement residue removers Glass cleaners Industrial cleaners

 

What are the risks associated with extreme pH values?
Highly acidic or alkaline solutions can – when used incorrectly – cause damage to health, the environment and materials. They can affect and damage the skin in particular. Only the pH range between 6 and 8 is relatively harmless.

Safety information: Protective measures (protective goggles, protective gloves, observing the safety data sheet) are vital when handling all cleaning products. Contact with the skin and eyes must be avoided at all costs.

When are pH tests used?
pH tests are recommended in the following situations:

  • Basic cleaning: If after basic cleaning (= removing the coating from a floor) a new coating is to be applied, it is essential that the floor is within the neutral range. The new coating will otherwise not be able to properly bond with the floor. It is therefore necessary to rinse the surface between these two procedures. After rinsing, a pH strip can be used to check whether the floor is back in the neutral range (between 7 and 8) or another rinse is needed. Simply apply a small amount of water to different areas of the floor and then check each spot of water using a separate pH strip. Once the pH value has settled at 7, there is no more basic cleaning solution left on the floor.
  • Training new staff members: Demonstrating a pH test is often useful for giving new staff members or those new to the cleaning industry a feel for pH values and the correct use of cleaning chemicals.
  • Assessing unfamiliar chemicals: If cleaning staff are working with cleaning products they are unfamiliar with or that are not labelled, a pH test can provide clarity regarding the area of application. Caution: Do not place any unlabelled chemical container on the shelf! These must be immediately handed over to a trained cleaning professional for proper disposal.

Widespread misconception & overestimation of pH values
Let’s finish up with an old cleaning myth: Cleaning staff often believe that professional cleaning products cannot remove both limescale and greasy dirt. This is not true! Cleaning products that contain surfactants or solvent-based ingredients may very well possess this 2-in-1 power.

The bottom line is that pH values are useful, but they are not the measure of all things. Surfactants and solvents also have an impact on cleaning performance that should not be underestimated. Cleaning products that can remove both grease and limescale do exist. In practice, it is therefore important to observe the manufacturer’s instructions on specific areas of application on the label of the cleaning product.