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Understanding the Relevance of the pH Scale


Posted on January 13, 2012
By Gary Fage

Understanding the relevance of the pH scale when carrying out cleaning tasks is vital to anyone that is serious about commercial cleaning

In general terms acidic products (less than pH 7) have descaling properties. Alkaline products (greater than pH 7) have degreasing properties.

The pH Scale is a means of measuring the degree of acidity or alkalinity of a cleaning agent or solution, simple, easy-to-understand, numeric terms. The scale itself has a range of 0-14,with 0 being the most acidic and 14 being the most alkaline. The mid-point on the scale is 7 and is classed as neutral and this corresponds with the pH measurement for distilled water.

Acidic Products

When a pH value of a product or solution decreases below 7, its acidity will start to increase. Most acid based cleaning materials will have a typical pH value of between 0.5 and 5 on the scale. Concentrated pure acids will have a pH value of approximately 0.1, though these would never be used as cleaning as cleaning agents.

Acidic products are most commonly used to remove limescale deposits from hard surfaces as they will dissolve salts that are not soluble in water.

Alkaline Products

As you can see from the chart, if the pH value rises above 7, the product or solution will become more alkaline. Alkaline products are particularly effective in removing greasy and fatty deposits from hard surfaces. They will typically have a pH value of between 11 and 12.5. Stronger alkaline products such as emulsion floor polish strippers will have a value of around 13. Caustic soda, which is extremely corrosive, will have a pH value of 14.

Neutral Products

As we have pointed out earlier, the pH of distilled water is 7 which is taken as being the purest neutral solution. However, in reality, any product or solution with a pH value of between 6 and 9 is generally considered to be neutral. Neutral products are commonly used for general cleaning procedures and include washing-up liquid and carpet cleaning solution.

How is the pH Value Tested?

The approximate pH value of any liquid product or solution can be tested using Universal Indicator Paper, a type of litmus paper you may remember from science lessons in your schooldays. After being dipped into a solution the colour of the paper will change.

The colour of the paper can then be compared with a colour chart, the colour corresponding to the relevant value on the scale. The colours are illustrated in the chart at the head of this section.

About Gary Fage
Gary Fage has been Managing Director of Janitorial Express, since 1991, he is a Director of the Jangro Group and Council Member of the CHSA. www.janitorialexpress.co.uk