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Think You Know the PH Scale? – The Difference Between Acidic and Alkaline Cleaning Products

The Difference Between Acidic and Alkaline Cleaning Products

Cast your mind back to your school days and chemistry lessons and, besides several near-miss explosions and the child that always burned himself on the Bunsen burner, you will probably remember spending copious amounts of time dipping litmus paper into solutions to test acidity and alkalinity.

Just in case you’d forgotten, the term pH symbolises the hydrogen ion concentration in a solution (for example, what proportion of a solution contains hydrogen ions). The pH scale goes from 1—14. A pH of 7 is neutral, meaning that the amount of hydrogen ions and hydroxide ions in a solution are equal. For example, water has a pH of 7 because when water breaks up, the split is equitable into one hydrogen ion for every hydroxide ion.

Enough of the science, we’re more interested in the application of the theory as far as cleaning products go, and how the pH value can affect our choices in cleaning products. In general terms, acidic cleaners are great for brightening metals and removing mineral deposits or oxidation on surfaces. Alkaline cleaners, on the other hand, remove oils, fats, greases, and proteins. Alkaline cleaners are more commonly used than acidic although a combination of the two is sometimes the optimum application.

Acidic Cleaners

When we think of common acidic cleaners, our first thought often goes to vinegar, which is a dilute solution of acetic acid, or maybe lemon juice which is a citric acid. Both can help to remove mineral deposits, such as limescale or rust stains, particularly from sinks and glassware. Both citric acid and acetic acid are weak acids. Oxalic acid is a stronger acid that’s sometimes used as a rust remover. Sodium bisulphate, hydrochloric acid and sulfuric acid are even stronger acids that are sometimes included in toilet cleaners.

Alkaline Products

Baking soda or sodium bicarbonate is a weak base sometimes used to clean glass and wall tiles. Dilute solutions of ammonia are stronger alkaline cleaners and often used for glass cleaning, floor cleaning and other surfaces because it doesn’t leave a residue when dry. Chlorine bleach is an alkaline solution of sodium hypochlorite dissolved in water. Used to clean and whiten fabrics as well as surfaces, chlorine bleach also works as an effective disinfectant. Trisodium phosphate and sodium carbonate, or washing soda, are also alkaline cleaning agents. A strong degreaser Trisodium phosphate (TSP) is often utilised to prepare walls for painting. Also used in the cleaning treatment of mildew as well as soot and smoke damage. Lye or sodium hydroxide is a very strong base and is sometimes found in drain and oven cleaners.

In summary

Acidic cleaners are best for removing mineral deposits, rust stains or discolouration from copper and other metals. Alkaline cleaners, by contrast, are especially good at breaking down fatty or oily deposits, which is why many laundry detergents are alkaline, or basic. Chlorine bleach is a base and is especially good at removing stains and dyes from clothes as well as disinfecting.


Cleaning products at both ends of the pH scale pose a risk as they are corrosive to human, animal and plant tissue and at the highest end of the scale can actually eat into the tissue and are described as caustic. Some cleaning materials are toxic and if mixed with other chemicals can produce poisonous gases. Always read the label, take care when using and store safely.

All Monthind operatives are health and safety trained, with particular attention paid to the use of cleaning products, and wear/use PPE appropriate to the task. COSHH assessments are completed for every contract and regularly reviewed.

If you would like to find out more about the services we offer and how we can help your organisation to go off the scale in terms of cleanliness

Call us on 01206 215300

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