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Ian Harper

ALL You Need TO Know About How Surfactants Work

45 min read

How Cleaning Agents Work

Cleaning Agents

There are a wide range of cleaning agents. Partly this is because of the presence of specialist floor strippers, partly because of shampoos and de-stainers for soft floors.

However, the main reason is that various specialist surface cleaners are needed above floor level. These are

  • Many Types of surface
  • Hygiene requirements for certain surfaces or certain situations
  • A number of types of dirt, for example, hard water scale

Whilst it is often necessary to keep a range of cleaning agents, it’s advisable to keep this as limited as possible.

  • For economy in manufacturing, buying and stockholding
  • To make training of staff easier
  • To meet responsibilities under chemical safety regulations

Please note that the use of disinfectants should be done after a surface has been cleaned.

Cleaning is described as the removal of unwanted material without damaging the surface to which it adheres.

By unwanted material we mean the dirt found in any building, examples are:

  • Dust and grit
  • Oil and greasy marks
  • Cigarette ends
  • Little and waste paper
  • Food and drink spillages
  • Possibly many other things as well!

The important thing to recognise some of the things we are up against. Almost anything can be unwanted material if it’s in the wrong place. Removal of soil is the main task in cleaning.

What is a cleaning agent?

Equipment is available to help us remove soil. But often removal of unwanted material needs a cleaning agent as well. These are the chemicals we use on the many types of surfaces found in and around a building. So

  • A cleaning agent is a product which assists in the removal of soil

How does a cleaning agent work?

In other words how does a cleaning agent do its job? How does it remove dirt?

There are three things it does

  1. Firstly, the cleaning agent must cover the surface and penetrate the dirt. Although some cleaning techniques are done dry. We will usually be using our cleaning agent in water. So we can say
  • cleaning agent must be a good wetting agent
  1. The cleaning agent must assist in getting dirt off the surface. Often some scrubbing or wiping will be necessary as well, but we can say
  • cleaning agent must assist in lifting dirt from a surface
  1. We now come to the last important step removing process. The cleaning agent must hold on to the dirt and prevent it settling back on the freshly cleaned surface. Dirt held in a cleaning solution in this way is said to be “in suspension” so then finally.
  • cleaning agent must hold dirt in suspension.

So, a cleaning agent is a chemical product which does these things in this order.

  • Penetrates soil and wets a surface thoroughly
  • Helps in lifting the dirt off the surface
  • Keeps the dirt off the cleaned surface by holding it in suspension

Armed with this, we are ready to think about the range of cleaning agents available

Water as a cleaning agent.

Water is one of the simplest chemicals there is. The simplicity of its chemical formula h2o suggests this. It is the simplest cleaning agent as well.

Most people would say that they hardly ever use just plain water for cleaning in their day to day work. Well maybe so, but it is worthwhile remembering that water was the first cleaning agent of all.

Most of us still have an instinct which is a very useful one from a safety point of view; if you get something nasty on your hands, wash it off immediately with water! But water is now more important to us in the cleaning industry for diluting and rinsing than it is as a cleaning agent in its own right.

For example, the use of water in high pressure cleaning. High pressure cleaning is one of the few cleaning techniques in which water can be used on its own.

The pressure of the water jet is used like a knife to cut dirt away from surfaces.

Sometimes it helps to use hot water. Sometimes you still need a cleaning agent.

  • The pressure of the water jet used does most of the work
  • Hot water may be used foe some jobs
  • A cleaning agent is often added to speed up cleaning action of the jet

We can explain why water is a poor cleaning agent by looking at its chemistry.

You know water is often spoken of as “good old h2o!” that’s its chemical formula and its structure

Water is two atoms of hydrogen joined to one of oxygen. The whole collection of atoms is known as a “molecule” of water.

We’re now ready to have a look at how (and why) water behaves in the way it does.

Water molecules attract each other, the hydrogen of one molecule attracting the oxygen of the next.

If you can imagine a bucket on water and you could take a real good look at the edge of the bucket with the surface layer of water molecules is attracted downwards towards the main body of the water. This produces a kind of “skin” effect at the water surface. This is called water tension it will keep the water droplet on a vertical surface preventing it from running down.

Water molecules are good at attracting each other. But they are usually bad at being attracted onto the dirty surface that you’re trying to clean.

Unless the dirt dissolves easily, water just doesn’t attract it away from the surface. Insoluble, oily or greasy soil is usually left unmoved.

Another drawback is that water is not very good at holding the dirt away from the surface if it should come off.

In other words

  • Water is a poor wetting agent, it prefers to stick to itself
  • Water does not lift dirt from surface well
  • Water is no good at holding dirt in suspension

Comparing these three points with what we looked for from a cleaning agent, we can say

  • Water is an ineffective cleaning agent

Water, pure, hard or soft.  

In this section you’ll find out

  • What the difference types of water are
  • What makes water hard or soft
  • The problem with hard water

Many of us think that water which comes from the domestic supply for drinking purposes is pure water. A chemist though would argue that this water is not pure water because it contains small amounts of things other than water.

To a chemist, pure water is distilled water. It is nothing but water, but it taste flat, lifeless and horrible. It seems nothing like drinking water at all, although it isn’t poisonous.

The reason why drinking water tastes different to this really pure water is that it contains some minerals which have dissolved in it from the rocks over which it has flowed. These are the rocks of the river bed etc and exactly what has gone into the water will determine whether that water will be termed hard or soft.

By hard water, we don’t mean ice!

Hard water is water that has dissolved minerals from the rocks which contain calcium, although magnesium and iron minerals can sometimes have the same effect.

Rivers which flow through the countryside pick up some of the calcium in a chemical reaction which uses one of the gases in the air, carbon dioxide. The calcium is dissolved in the water as calcium hydrogen carbonate. (Or calcium bicarbonate)

Water containing calcium in this form is known as temporary hard water. Quite why it should be temporary, we shall see later.

Permanent hard water which contains calcium in this form of calcium sulphate. Has to flow over the right sort of rocks to be formed.

If the water contains little calcium, magnesium or iron then it will be termed soft water. Quite simply, this is water which has flowed though countryside where the rocks don’t dissolve very much.

Hard and soft water differ in a number of ways, but for us, the most important difference concern the way in which some of our cleaning chemicals behave in these different types of water and the way in which they can be affected by heat.

It is hard water which is always the problem, whether temporary or permanent

The problems are as follows

  • Soap form “scum”
  • Some disinfectants may be less effective
  • Rinsing water can leave chalky smears
  • Water deposits “scale or fur” when heated

Scum is a chemical formed when calcium combines with soap anion in hard water.

In most cases this can mean total loss of the cleaning power of the soap, with the soap forming a sticky layer of scum which just goes to make the surface being cleaned more dirty than it was to start with.

This expensive loss of soap has meant its almost total replacement by synthetic detergents in the cleaning industry.

In addition, some phenolic disinfectants are less effective in hard water, as are the quats.

The presence of chemicals such as certain builders and chelating agents in manufacturer’s detergents and disinfectant blends help to reduce this problem.

In areas where the water contains a lot of calcium and is very hard, rinse of some cleaning surface such as glass, stainless steel, chrome etc leaves obvious chalky smears. The only answer is to polish off these surfaces after rinsing.

The problem of formation of scale or fur occurs in temporary hard water areas with equipment in which the water is heated before use. This is exactly the same as occurs in domestic kettles and immersion heaters where the heating element becomes covered with hard off white deposits.

This is the calcium carbonate that was dissolved from the river bed! The problem can occur in hot water extraction machines, heated high pressure washers.

The problem is lessened if the water is not allowed to get near to boiling, and after if a detergent solution is being heated, it will in all probability contain chelating agents to reduce the effect of the calcium.

In soft water areas there are few problems, except that you might find yourself using too much soap when washing!

We can now look at some more effective cleaning agents.

Soap and Detergents: The Surfactants

It’s quite simple to show that a soap or detergent is more effective cleaning agent than water. You will need two glasses of water, one with a teaspoon of dirt added and one with a teaspoon of oil added.

You will also need some soap solution or a detergent.

Find in your home some water that has formed into globules. Like on a shower door or car bonnet. Spray the detergent onto the globules of water. The globule should collapse. This can be seen very well when the globules are standing on glass.

This happens because the detergent used is acting as a wetting agent. It reduces the surface tension of the water allowing the water to spread out and really wet the surface to be cleaned.

So to get to the dirt you must first break down the surface tension of the water, It’s just like using the detergent as a knife to cut though the water to get to the dirt.

The detergent then goes on to hold the dirt in suspension to be swept away by the water that is always present in cleaning.

The Components of a Commercial Detergent

These are the most widely used cleaning agents. Manufacturers use a number of different chemicals in their products.

  • Surfactant – very important described already.
  • Alkaline builders – they help to break down grease in stubborn greasy dirt and then keep it in suspension.
  • Organic solvents – these are also used in products designed to deal with greasy dirt. Wax removers are another type of detergent blend containing organic solvents.
  • Suspending agents (anti-redeposit ion agents) – as their name suggests, these will help to keep dirt in the cleaning solution and not allow it back onto a cleaned surface.
  • Chelating agents – these help reduce the effect of calcium etc which will be present if the domestic water supply is “hard” in your area.
  • Optical brighteners – these may be used in detergent blends for use on carpets and upholstery fabrics. They seem to increase the amount of light coming from the cleaned material, so making it looks brighter (and cleaner).
  • Form stabilisers – these chemicals make detergent foam last longer. This can be useful when cleaning vertical surfaces for example. The cleaner solution stays in contact with the surface longer if the foam lasts.

There are many other possible ingredients which may be used in “speciality” cleaning agents these are the conditioners, enzymes, oxidising agents, corrosion inhibitors, and so on. But these are not present in many of the everyday detergents used in the cleaning industry.

Dyes and perfumes are often included in commercial detergents. They only make the product nicer to use, not better at its job.

Detergency: The Way Surfactants Work

Most people find this fascinating subject.

They appreciate their soaps and detergents rather more when they find out exactly what goes on in the cleaning process.

All surfactants have two things the same in the structure of their molecules (or ions)

  • There is a long chain of carbon and hydrogen atoms (which may include a ring of atoms as well)
  • There is a group of atoms at one end of the chain which carry some electrical charge.

The carbon and hydrogen chain is water hating. It will arrange itself so that it is up against a surface other than water if it possibly can. It will Evan poke out of the water into the air.

The technical name for this sort of behaviour is “hydrophobic”, which means water hating.

The group of atoms caring the electric charge is completely the opposite. It prefers to be surrounded by water. This type of behaviour is called “hydrophilic” water loving.

There are four main types of surfactants, known as anionic, non-ionic, cationic, and amphoteric.

They differ in the electric charge which is carried by the group of atoms which make up the tadpole head.

  • Anionic – negative charge (-)
  • Non – ionic – fairly small negative charge (-)
  • Cationic – positive charge (+) these are not very efficient surfactants
  • Amphoteric – can be either a positive or negative charge, depending on the ph of the solution (+ or - )

The fact that different surfactants can have different sizes and types of electric charge does not affect the way they work. However, it can be serious if the types are mixed.

The following series of diagrams show how surfactants work.

  1. Wetting the surface and the dirt.

At the first step in the cleaning process, the surfactant “tadpoles” crowd on to anything that isn’t water. Their hydrophobic tails point inwards away from the body of the water

Surface tension is reduced and the cleaning solution creeps along covering both dirt and the surface to be cleaned with a layer of surfactant.

The surfaces of patches of greasy dirt and particles of dirt become covered with the “tadpoles” as the diagram shows.

2.lifting the soil from the surface

















Next, the electrical charge on the hydrophilic head of the “tadpole” begin to play its part. We shall use negatively charged soap or anionic detergents to show how the dirt id lifted from the surface. They behave similarly to non-ionic and amphoteric surfactants, if not exactly identically.

The best way to show how dirt is lifted from a surface is to look again at the first diagram along with the next two. Notice how the particles of dirt have left the surface

Greasy and oily dirt

have formed into droplets and these are also floating clear of the surface. This is due to the electric charge on the “tadpole” heads

Each negative charge repels its neighbours. This means that those detergent “tadpoles on the cleaned surface force away those which are attached to dirt particles.

But the tadpoles don’t come away from the dirt. They carry the dirt away from the surface with them as they go! In the case of oil or greasy dirt, this is not only pushed away from they surface. It also breaks up into smaller droplets and forms an emulsion.

The detergent which will do this all on its own without any sort of agitation hasn’t been invented yet. But it would be a great idea!

3.keeping the dirt in suspension

the final job of a surfactant is to keep the dirt in the body of cleaning solution and away from the cleaned surface, again, this relies on the electric charges on the hydrophilic “tadpole heads.

The “tadpole” which now cover al the cleaned surface (see final diagram) carry on repelling those on the dirt particles, oil and grease droplets etc. this prevents the dirt settling out on to the surface again.

Repulsion between the “tadpoles” on the individual soil particles and droplets also prevents the dirt from joining up into lumps, that is, it stops the soil from coalescing.


Next time you see soap or detergent being used, remember the “tadpoles” with their hydrophilic heads and their hydrophobic tails. Don’t try and look for them though! The largest detergent molecule is only about one millionth of the size of a real tadpole, and they’re pretty small anyway!

What are the differences?

You’ll know by now that there are some small differences in the chemical structure of surfactants. But they all clean in a roughly similar way.

There are some differences in the way they behave though. Manufactures often combine surfactants in their products, as together these differences give a better detergent action. This section considers how each type performs.


Good points

  • good wetting agents
  • good at lifting particulate dirt from surface
  • hold soil in suspension
  • no problems with hard water
  • very good foam formation
  • nice and cheap

Bad points

  • can produce skin allergies or dermatitis in some people
  • can’t be used in acid products
  • can’t be used in combination with cationic

Soaps are a different class of anionic material and are discussed more fully later.


Good points

  • Some disinfecting power
  • Good at reducing static electricity
  • Fabric conditioning properties

Bad points

  • Not very good wetting agents
  • Poor at removing greasy or oily dirt from surfaces
  • Not good at keeping dirt in suspension
  • Can’t be used in alkaline solutions
  • Can’t be used in combination with anionic
  • Quite expensive

For the above reasons, cationic are normally only used in detergents blends where disinfecting capabilities are required. They are such poor detergents that they cannot really be considered as such.


Good points

  • Good wetting agents
  • Good at lifting soil from surfaces
  • Good at keeping soil in suspension and preventing redeposit ion
  • Low foam production
  • Rinses of cleaned surfaces easily
  • Can be used in acidic, neutral and alkaline solutions
  • Can be used with abionics cationic or amphoterics in a detergent blend.

Bad points

  • May not be suitable for use in hot water
  • Were expensive, but are becoming cheaper


Good points

  • Good wetting agents
  • Very good at lifting soils from surfaces
  • Can be used in both acidic and alkaline solutions
  • Can be blended with anionic, cationic or non-ionic
  • Greatly improved detergent performance when blended non-ionic. The good points of each help to cover the bad points if the other, called synergism.
  • Non-toxic and relatively harmless to skin

Bad points

  • Rather expensive
  • May be some loss of detergent activity in near neutral solutions

Do note one point in particular here

Anionic and cationic must never be mixed

The two cancel each other out and result in no cleaning ability at all.

In formulating their products, one manufacturer may mix non-ionic, amphoterics and a cationic in one product. A competitor may blend non-ionic and amphoterics with an anionic in theirs.

In the container and in use, both may seem identical. But the two must never be mixed

Leave blending of detergents to the manufactures and their chemists.

What’s in the detergents you use?

This is a question you can now go some way to answering yourself. Armed with your list of surfactants and other components you’ll be able to get the main ingredients right.

We want to ask you to

  • List the brand name of each of the detergents you use
  • Say what the product is used for
  • List the components you think might be in the blend.

This example should give the idea.

Let’s just consider the reasoning behind the answer.

A window or mirror must look completely clear after cleaning. So we want a detergent that’s good at removing soil and one which can be rinsed away easily without leaving streaky marks.

If you look at the good points of a non-ionic surfactant you’ll see where we got that part of the answer.

Leaving behind greasy marks can be the biggest problem with glass cleaning, so it would be a good idea to include something to help with removing the grease.

Alkaline builders are a possibility but could cause a problem if they splashed on to something else.

There could be rinsing problems as well. So what about organic solvents to do the job instead?

As for the perfume and the dye, we can see and smell what’s in our container of glass cleaner, it make it easier to identify.

We hope you can fit your list examples into one of out categories.

General purpose (or neutral) detergent

For routine cleaning of most hard surfaces which are not very dirty.

These almost always contain an anionic surfactant as the main component. Often this is blended with a non-ionic amphoteric.

A little alkaline builder may be present together with chelating and suspending agents. Probably dye and perfume are present as well.

Heavy duty (or alkaline) detergent

For the cleaning of heavily soiled hard surfaces.

Surprisengly, these have the same components as neutral detergents, except they have a lot more alkaline builder.

This removes greasy and other soils bound to the surface, as usual, take care when using high ph products.

Water based emulsion polish stripper 

These are alkaline detergents as well, so must be used with caution.

Strippers designed to remove metallised water based polish will either have to be highly alkaline (ph 11.5 or more) or will have to have an extra ingredient to break down the metal complexed polymer.

This will normally be an ammonia derivative. There is more about strippers in the seals and polishes manual.

Bactericidal detergents

Used in hard surface cleaning where soiling is moderate and some disinfecting is required. Examples are food preparation and kitchens.

These detergents contain a cationic surfactant for its bactericidal properties. More often than not these are blended with a non-ionic or amphoteric for improved cleaning efficiency. Chelating agents, dye and perfume may also be present.

Antistatic cleaner

Particularly for plastic surfaces where dust build up is found to be a problem.

These are similar to bactericidal detergents. The cationic surfactant remains on the cleaned surface to give it antistatic properties. Most dust is then repelled from the surface.

Carpet & upholstery cleaning detergents

These are many and varied.

The components in a blend will depend largely on the cleaning technique. But there are several different formulations possible even then.

Some products you may have considered are.

Hot water extraction detergent is mostly a low foaming material containing non-ionic surfactant. Some anionic cationic may be included (but not both). If cationic material is present it will leave the fabric with anitistic properties. Suspending agents dye and perfume may also be present.

Some products have alkaline builders present as well (care!) these can produce problems and are really for use by the carpet cleaning specialist.

Wet shampoos need to produce some foam, but it must not be long lasting. These are mostly non-ionic and anionic surfactants in a blend, with a dye and perfume.

Dry foam shampoos should give stable foam which crystallises (dries out) and holds the dirt in the foam. These may be anionic surfactant alone.

You may also have mentioned wash and wax polishes and buffable gel cleaners.

This is quite correct as these materials have a detergent component. Their real use is for the protection of sealed sheet and tile resilient floors. We have therefore covered these in the seals and polished manual. By now, you will probably agree that there is quite a lot to the question, “what goes into a detergent blend and why” hopefully you will have found a fair amount of agreement between your answers and the above list of “possibilities”.

But do remember though that manufactures detergent blends can be very complicated or quite simple. What we have tried to do here is get some idea of what is likely to be in your cleaning agents. There will be some additives and combinations that neither of us has mentioned!

You may have considered some cleaning agents other than those which we have classified as detergents,

Such materials could include soaps, degreasers, descalers, solvents and the abrasive cleaners such as cream cleaners, metal polish etc.

We’re going to look at them individually a little further on, together with their uses and some “do’s and don’ts” concerned with their use. Next we highlight problems which can occur in the use of detergents.

so, we would expect to find corrosive, strongly acidic materials with ph values from ph 0 – 3, with the possibly even more dangerous strong alkalis 10 – 14.

Materials with ph’s between 4 and 7 are weakly acidic anf those between 7 and 9 are weakly alkaline.

Manufacturers of cleaning chemicals will iften call weakly acidic or alkaline materials “neutral” as in the term sometimes used for general purpose detergents “neutral detergents”

These may have ph value as high as 9. to a chemist there is only one really neutral ph value however, and that is a exactly ph 7. materials with ph 7 are neither acidic nor alkaline, and this is the chemists definition of neutral.

When acids and alkalis are mixed there is a chemical reaction known as neutralisation. This brings the ph of the mixture closer to 7, or exactly to 7 if you’re luck (or very careful)

This can be a fairly dangerous business with strong acids and alkalis, because of the large quantity of heat produced at the same time.

In some cases though, neutralisation under safe conditions is important part of a cleaning technique, as in preparing newly stripped floors for sealing or application of polish, or during some carpet cleaning operations.

If we need to make sure that a floor surface is neutral, or at least has a ph value in the right region, we need to be able to measure ph values. The simplest way to do this is with universal indicator paper. This is available as dyed strips of absorbent paper.

When dipped into an acidic, alkaline or neutral material strips of universal indicator paper will change colour depending on exact ph in the solution. The colour of the paper can then be compared with a colour chart which gives all the different possible colours and ph values which correspond to them.


Problems in the use of detergents

Many of these are related to the degree of acidity, or more usually alkalinity, of the detergents.

Before we proceed you’ll need to know more about acids, alkalis and the ph scale which measures their strength.

Acidity, Alkalinity and pH

Here we deal with

  • Some typical examples of acidic and alkaline materials
  • The corrosive nature of acids and alkalis
  • Acid and alkaline strength with the ph scale
  • Neutrality and neutralisation
  • Measuring ph
  • Precautions when using acids and alkalis
  • What to do in case of spillage

Most people will have heard the terms acid and acidity being used in everyday life, as well as being applied to some cleaning chemicals. This familiarity with these terms gives us a good place to start.

Some examples follow

  • Battery acid in a cars batteries (this is sulphuric acid)
  • Acids in fruits, especially in lemons, limes etc (citric acid)
  • Vinegar, which is acetic acid
  • Sour milk and yoghurt, which contains lactic acid
  • Fizzy drinks, such as lemonade, cols, soda water etc which contains a weak acid known as carbonic acid.

Some of the chemicals used in the cleaning industry are acidic as well.

We can include

  • Toilet descalers
  • Some disinfectants
  • Etching agents for concrete

From these lists, you may know that there are some things that acids have in common.

For example, they are all corrosive to some extent, particularly when in contact with metal. You can see this if you cut a piece of fruit with a knife which isn’t stainless steel. Very often the blade will go black quite quickly, especially with lemons.

Concrete, marble, limestone, terrazzo are also easily corroded.

So corrosiveness is a property associated with acidity.

In some cases, the acids we use are so corrosive that they can be potentially hazardous. This is particularly true of some descalers and acidic drain cleaners. The best tactic is to always treat acids with some respect.

Details of safety precautions and accidents procedures follow shortly.

The opposite of acidity is alkalinity, and so the opposite of an acid is an alkali.

This is probably less familiar than acids and acidity, but there are a few everyday materials which are alkaline

  • Milk of magnesia
  • Bleach, which contains a strong alkali

Many of the chemicals used in the cleaning industry are alkaline to some extent, and we can include the following in addition to bleach

  • Many general purpose detergents
  • Heavy duty detergents
  • Water based polish strippers
  • Some paint and seal strippers

Alkalis can be corrosive too. But in this case it is organic matter which is most readily attacked

Highly alkaline materials can be particularly dangerous.

Organic matter includes anything which comes from living things, so we can say that our skin, natural fabrics like wool and cotton, wood, paper etc may be attacked by alkalis. Aluminium metal may also be attacked.

Although we’ve mentioned potential hazards, not all materials we have described as acids or alkalis are particularly corrosive. Acids such as those in lemonade don’t dissolve metals, and milk of magnesia doesn’t attack human skin.

On the other hand, sulphuric acid and the acids in descalers are very corrosive, as are the alkalis in bleach, strippers, and some drain cleaners.

The differences one of strength of acidity or alkalinity. Some materials are more acidic than others and the same goes for alkalinity too.

A convenient way to look at the different acids and alkaline strengths. This is known as the ph scale, and is given by its ph value, between 0 and

As you can probably tell from the ph scale, the most dangerous materals are at either end. Those materials which are fairly harmless have ph values near the middle of the scale.

Precautions when using acids and alkalis

Some of the hazards of using acids and alkalis have been mentioned already.

It is useful to known some of the precautions that should be taken when handling highly acidic or highly alkaline materials. Sooner or later, it will be necessary to deal with an accidental spillage of such materials.

Strongly acids (ph 0 – 3)

In use

  • Note hazard labelling, with risk and safty phrases
  • Follow manufacturers instructions carefully
  • Always wear glover
  • Wear eye protection if there is any possibility of splashing
  • Wear protective foorware if working on floors
  • Don’t leave residues where they can do damage (rinse away)
  • Store in a well labelled storage area which is easily accessible

If there is a spillage on to the person

  • Firstly, wash hands, face, eye clothing immediately using large quantity of cold water.
  • Then apply neutralising lotion to skin, such as sodium hydrogen carbonate

(sodium bicarbonate) in water, or a glycerol/magnesium oxide paste

  • If eyes have been splashed or if blistering or a burning sensation is felt on the skin, obtain medical attention.

If there is spillage of strong acid onto floor, furniture, fixtures etc

  • Close area, or place warning signd
  • If spillage is large, in addition to gloves wear rubber boots and face shielf.
  • Neutralise the spillage by covering with solid sodium carbonate (washing soda)
  • Sweep up solid residue, wash area with plenty of water and mop up.

When using weakly acidic solutions, it is advisable to wear gloves at all times and to rinse areas affected by spillage. This is particularly true of spillages onto surfaces likely to be corroded(metals, concrete and stone floors.

Strong alkalis (ph 10 – 14)

In use

  • Note hazard warning symbols, with risk and safty phrases.
  • Follow manufacturers instructions carefully
  • Always wear gloves
  • Wear eye protection if there is any possibility of splashing
  • Wear protective footwear if carrying out a floor treatment
  • Don’t leave residues where they can do damage (rinse away)
  • Store in a well labelled storage area which is easily accessible

If there is a spillage of strong alkali on to the person

  • Wash hands, face eyes, clothing immediately using a large quantity of cold running water
  • If eyes have been splashed, or if a burning sensation is felt on the skin, obtain medical attention

If there is a spillage on the floor, furniture, fixtures etc

  • Close area or place warning signs
  • If spillage is large, in addition to rubber gloves, wear rubber boots and face shield
  • Dilute spillage with cold water and mop up
  • Rinse area with plenty of water and mop up
  • If surface is particularly sensitive to alkaline residue, rinse finally with dilute solution of sprit vinegar

Weakly alkaline solutions

  • It is advisable to wear gloves at all times
  • Rinse areas affected by spillage

Now we can consider the problems in the use of detergents.

There is one group of surfaces that should never be treated with any detergent solution at all, nor with water for that mater.

They are things like unsealed wood and cook, other wood group surfaces that behave similarly, such as unsealed magnesite, granwood. Detergent solutions and plain water will soak into these, unless they are protected by a seal or polish. All would have their surfaces roughened by detergents. In some cases cracking or breaking up of the material may occur.

Now, back to other detergent problems.

General purpose (or neutral) detergents, ph 7 – 9

Here the name “neutral” means that the detergent is not likely to damage anything, rather than to suggest that the ph is exactly 7,

Surfaces particularly sensitive to alkali could be damaged by detergents of ph 9 – 10

These include

  • Aluminium
  • Unsealed linoleum
  • Surfaces treated with non-metallised water based polish

Testing the ph of your genral purpose detergent could be very useful.

Another problem here is that some people are sensitive to anionic detergent. To avoid dermatitis always wear rubber gloves when using a detergent solution

Heavy duty (or alkaline) detergent and water based emulsion polish stripper, ph 10- 13

The alkali content is certainly the problem here

These detergents must never be used on aluminium. Where stripping water based emulsion polish from linoleum, prolonged contact will cause damage. The same applies to wood group floors,( such as wood, cork, granwood etc.) where the seal may not be sound.

The regular use of alkaline detergents on the other surfaces will make them become porous. Marble, terrazzo, even thermoplastic. Will all go dull and porous if cleaned too often with alkaline detergents, or left unrinsed afterwards.

Irritation, cracking and even blistering of you skin will happen unless you take care using these detergents. So gloves are a must.

If there is any possibility of splashing, eye and face protection is recommended.

Protective footwear may also be required.

Bactericidal and antistatic cleaners, ph 5.5 – 9

This category contains some of the few acidic detergents. Whatever their ph, they are only ever mildly acidic or mildly alkaline.

At ph 5.5 – 9 there is no longer danger to skin, clothes etc. in normal use, surfaces will not be damaged either.

Floors containing calcium carbonate in one form or other (marble, limestome, terrazzo) could be damaged by prolonged contact with mildly acidic bactericidal cleaners.

Am important point here is not confuse bactericidal cleaners with highly acidic products used as descalers, rust removers and drain cleaners (covered later). These may have ph values as low as ph 1 – 2. they can damage both people and surfaces id used incorrectly. Another good reason for knowing your ph’s.

Carpet & upholstery cleaning detergents, ph varies

There is a wide range. Mildly acidic, neutral and moderately alkaline detergents all find some use in carpet and upholstery cleaning.

Manufacturers instructions must be followed closely. Although neutral and nearly neutral products are unlikely to do any damage, the alkaline variety (care) must be neutralised after use. Permanent damage to fibre and colour could otherwise occur.

What about the detergents you use?

  • Why not answer this yourself?
  • You can find the ph of the detergents you use by following a simple
  • You will need to make up a small quantity of each of your detergents at the normal “in use” dilution.
  • As egg cupful will be plenty.
  • Carry out a ph test.
  • Dip an unused piece of universal indicator paper into each of your detergent solutions.
  • remember not to use the same piece of indicator paper more than once.

Check each ph comparing the colour of the indicator paper with the nearest on the universal indicator colour chart.

You should now have a good idea whether or not your detergents can damage people and surfaces!

Alkaline ph’s are likely to concern you most. Suppose your general purpose detergent has a ph value of more than 9.6?

Your must ask yourself two questions

  • Do I need this much alkalinity for routine cleaning?
  • Can I find an alternative with a ph value closer to neutral which will do the job just as well?

It is best to find a suitable product with ph near neutral, so that people and surfaces are safe.

If you are having to use a high ph detergent regularly, perhaps you are not cleaning often enough?

Speciality cleaning agents

How about those cleaning agents which are more than just detergents? Or which are based not on detergent at all?

These are best looked at in the way that you use them.

But do remember what you have learnt about the properties of the different surfactants, additives, problems of ph and so on. Similar questions will crop up in dealing with these cleaning agents.

Abrasive cleaners

These are chemicals which “wear away” at soil that is tightly bound to surface.

This is what we mean by abrasive.

This category includes

  • Cream cleaners
  • Scouring powders
  • Metal polishes

We’ll consider them in turn.

Cream cleaners

These are thick liqids, creams and pastes used for hard surface cleaning.

The abrasive should be fine, soft power. The soil is worn away but the surface beneath is left undamaged. In pratice, there is always some damage. They should never be used as a routine on surfaces soft to be harmed, paintwork, plastics etc.

Some varienties which are more abrasive than others deal with really difficult soils. As a rule, never use a gritty cream cleaner if one with a gentle action will do the job, even if it does take longer.

Most cream cleaners contain anionic and non-ionic surfactants, with possibly an amphoteric as well. It is, after all all stubborn and difficult to remove dirt that we are dealing with here.

As grease is also often part of the problem, alkaline builders are usually added.

Do make sure that gloves are worn al all time and don’t use cream cleaners on aluminium.

Scouring powders

Intended for use as hard surface cleaners, these will normally contain a most aggressive abrasive. They will damage even the hardest surface if used at all regularly. Even glazed ceramic tiles anf viteous enamel will become scratched eventually.

Avoid using scouring powders if possible.


Bleach reacts badly with acids products poisonous chorine gas. Many people have taken the view that because of the risk of bleack mixed up with descalers it should be excluded from cleaning pratices.

Metal polishes

These are thickish liquids intended for use on brass, copper, chromium and other metals. Their best use is for the removal of tarnish or surface scratching.

The combination of abrasion and chemical attack removes part of the metal surface.

They should only be used for restorative purposes and not as part of regular cleaning.

Those metal polishes which are clear liquids or are available as impregnated cloths will not be abrasive. But their chemical action removes surface metal as well as tarnish and limits their use as well.

Electopated metal is particularly easily damaged.

Acidic cleaners

Acidic cleaning agents are extremely corrosive

They can be used safely in few situations.

They find use as

  • Descalers
  • Etching agents
  • Drain cleaners
  • Rust removers
  • Toilet cleaners

As with highly alkaline materals, these are precautions to be taken when using these highly acid cleaners as we detailed in the acidity, alkalinity and ph section before.


Scale is hard off white or brownish deposit which forms below water inlets in baths, hand basins and toilets in areas where the water supply is hard. Scale is normally calium carbonate, but may contain magnesium and iron compounds as explained earlier

Descalers are very highly acidic and quickly dissolve these deposits, along with the urine salts which sometimes stain them. The actual acids in descalers are usuall hydrochloric, phosphoric and formic acids. All are effective and are equally corrosive.

Well, bearing in mind that that they are very highly acidic, you would predict a very low ph value for your desclaers. Ph’s of 1 – 2 are usual.

Scale is mostly calium carbonate. So are floor surfaces such as marble, limestome and terrazzo. They are bound to suffer from acid attack. A spillage on these surfaces must be dealt with very very quickly indeed.

Concrete will be damaged as well as it contains calcium compounds, including calcium carbonate.

So will metal surfaces with descaler left on them.

Both non-ionic and amphoteric surfactants can be used in acid solutions.

The disinfectcting properties of the cationic quats are a useful addition here, as descalers are often used where hygiene is important.

Etching agents

Concrete is attacked by acids as it contains calcium compounds, including calcium carbonate.

This is why hydrochloric acid id used to clean of soild upper layer from old concrete floors before sealing. A fresh clean surface is left.

Drain cleaners

Drain cleaners can be based on sulphuric acid.

The acid eats its way though the blockage producing much heat in the process.

Strong alkali is also sold as a drain cleaner.

Great care mut be taken that on product is not used on top of the other. A dangerous combination of gas, steam and heat will be produced as the two cancel each other out.

If you are in any doubt on either product, consult the manufacter concerned.

Rust removers

Iron or steel may cause the familiar brown stains of rust to appear on surface

Most acids will dissolve rust, but only two unusual ones are at all goog at reducing the colour of the stain. These are oxalic acid and hydrofluoric acid. Both are poisonous as well as corrosive. This is particularly true of hydrofluoric acid which is unfortunately the better rust remover of the two. Follow manufactures instruction to the letter.

Alkaline degreasing agents

These rely on the greasy removing properties of strongly alkaline materials.

They are often called caustic cleaning agents.

They are available for use as

  • Drain cleaners
  • Oven cleaners
  • Degreasers

All strongly alkaline materials are extremely corrosive, they are more dangerous to the person than the acid cleaners of the previous section.

They have the highest known ph values of 12 – 14.

Pay careful attention to hazard labelling, risk and safty phrases, and any additional safety information.

Immediate damage will also be caused to wood, cork, wallpaper, carpets, and fabrics, linoleum and aluminium. Lengthy contact will affect thermoplastic sheets and tiles, marble, limestone and terrazzo flooring.

Alkaline materals attack grease by a process known as saponification. This destroys the grease, turning it into a type of crude soap (saponification means soap making) which can be washed and rinsed away.

If by accident you get intensely alkaline material on your hand, first thing you will notice is that they begin to fell slimy. This is the natural fat in your skin being turned into soap. It doesn’t sound pleasant and it isn’t.

As we have said before, use adequate protective clothing.

Drain cleaners

These alkaline materials act rather like strongly acidic relatives. They dissolve away any blockage. They are particularly useful in cleaning kitchen drains where soild grease is often the cause of the bockage.

The chemicals used may be sodium hydroxide (caustic soda the most powerful alkali of all), sodium carbonate or sodium silicate.

They must never be used with acidic drain cleaners.

What was said when dealing with acidic drain cleaners appkies equally well here, of couse.

Great care must be taken that one product is not used on top of the other. A dangerous combination of gas, steam and heat will produced as the two cancel each other out

If in any doubt consult the manufacturer.

Oven cleaners

These cleaning agents are designed to remove partly burnt grease in ovens.

A blend of strong alkali, anionc or amphoteric detergent id often applied as a foam, when it may be sprayed on with extreme caution.

Proucts applied directlt, by gloved hand, are probably safer to use.


In food processing industries, sodium silicate are used in soilid form with anionic or amphoteric detergent to remove fats and grease from floors and equipment.

They may be used in machinery cleaning in other industries and for drain cleaning.

Suitable protective clothing is an essential.


Soaps are a traditional cleaning agent which find little use in industrial cleaning today.

Their almost neutral ph makes them entirely suitable for hand washing. Solid and liquid soaps are still used for personal hygiene in washrooms, bathrooms etc. they are still used in laundering of fine fabrics.

“sugar soap” is soap to which alkaline builders have been added. It is still available, but it has been largely replaced by heavy duty alkaline detergents. These do the same job more effectively.

Some of the disadvantages of soaps have been mentioned already.

  • Scum formation in hard water
  • Poor rinsing qualities (leaves soap film)
  • Poor washing qualities in cold or warm water
  • Inefficient at grease removal
  • Expensive

Organic solvents

These chemicals are liquids, but they are not based on water.

Their main use is to remove soil, stains etc which are left behind by detergent solutions or water alone.

Organic solvents are useful for removal of some inks and dyes, oil and grease, tar, paint and adhesives.

They do have some drawbacks. They can attack some plastics, rubber and man made fibres.

They are either flammable (same meaning as inflammable, but more correct) or they give off harmful vapour.

In all cases, it’s best to try a detergent solution first before using solvents on a stain.

Then the best procedure is to start with mild solvent. Then move on to more aggressive solvents if you are unsuccessful.

First try                                               methylated sprit

Then move on to                                 white sprit

And last                                              acetone

Of these organic solvents, only methylated sprit will not harm plastic.

The sensible thing is to test hidden part of the surface with a little of the solvent before doing the stain removal.

All should be used in well ventilated conditions.

And do not smoke. It is not so much the danger of fire, but that their vapours become deadly in the presence of fire. If inhaled though a cigarette, even in quite small quantites, they can kill you.

Safety considerations require that flammable solvents be stored sensibly

  • In cool, well ventilated conditions
  • In well signposted store, where smoking. Matches and electric heaters etc are forbidden.
  • In metal lined cabinets, fitted with spillage trays.
  • With ready access to a suitable extinguisher

Solvent based detergents

Blends of mild organic solvents with detergent are useful for the removal of greasy or oily soil. They avoid the need to use alkaline detergents where they could be dangerous or corrosive.

However, there are types of solvent based detergent which can damage the surface being cleaned.

So, in order of “strength” they are

  • Window glass cleaner
  • Multi purpose cleaners
  • Wax removers
  • Paint and seal strippers

Solvents based detergents should be stored as for organic solvents

Window glass cleaners

These are a blend of detergent and alcohols. They remove greasy soil from glass effectively and are easily rinsed off, leaving no smears. They are too mild to damage surfaces.

Multi purpose cleaners

These are an alternative to alkaline hard surface cleaners. Detergent and mild solvents are blended with a little alkali (ph9) to assist in grease removal. They are not strong enough to be at all hazardous.

Wax removers

These blends of white sprit and detergent were developed for the removal of solvent based wax from wood floors.

They are also useful in removing tar and grease. They must not be used on surfaces which can be damaged by white sprit, such as rubber and some plastics.

Paint and seal strippers

These are probably the most aggressive chemicals available in the cleaning industry today. Their use should be very limited.

They contain strong alkali (ph 12 – 14), chlorinated solvents and detergent. They will damage almost all surfaces. Use them only in the last resort to remove well dried paint or seal. Their use should be infrequent.

Great care should be taken. The alkali content will produce immediate burns on the skin and the solvent gives off toxic fumes.

Using cleaning agents

There are some general points about using cleaning agents.

Health and safety

The problems of high acidity and high alkalinity have been mentioned on several occasions, so have possible causes of irritation or dermatitis.

All staff should know the potential dangers and give attention to

  • The importance of protective clothing
  • Training in making up and using cleaning agents
  • Noting hazard labelling and associated risk
  • Following manufacturers instructions carefully
  • The danagers of mixing cleaning chemicals
  • The labelling of cleaning agents that are to be stored after use
  • The correct storage of cleaning agents

Labelling cleaning agents

Some cleaning agents may be used straight from the container in which they are supplied. These will already be labelled.

Others may be more conveniently used in smaller labelled containers. Many have to be made up to the correct dilution before use.

In most cases, the dilution will be given in the manufacturers instructions. Any “in house” instructions for a different dilution should be clearly indicated on a separate lable.

Making up cleaning solutions

Many cleaning agents must be diluted with water before use. There is a golden rule

  • Always add the cleaning agent to the water, never the other way round.

This is to reduce hazards produced by splashing out of concentrated cleaning agents. It also prevents foaming which can lead to incorrect volumes being used.

The range of dilutions may be from 1 in 5 to 1 in 200. measureing aids are needed

  • Marked measuring jugs
  • Portion dispensers on containers
  • Distribution of prepacked portions
  • Pelican pumps
  • The cap of the standard 5 litre which will hold 1 fluid ounce

Marking of one or two of the more useful measured volumes on the buckets is also a good idea.

Fresh solutions

When should a fresh solution be made up during a cleaning operation?

There’s no easy answer to this question, apart from saying never use a solution that looks dirty” the trouble is that different people have different ideas on what is dirty and what is not. It also has something to do with the nearness of the water supply.

There are several points to be however

  • Always make up fresh solution when the result of the cleaning operation gets poor
  • Never store dirty solution for later use
  • Never top up a dirty solution with fresh concentrate or fresh water

You will need to decide your own standards and use firm and easy to understand instructions.