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Water - a most powerful detergent?15th of October 2010
Is the power of water sufficient for cleaning? More often than not, this may be true. While the role of electric ‘activation’ of water in cleaning remains unclear, the use of plain tap water as an effective cleaning means, or detergent, is increasing markedly. Anton Duisterwinkel writes exclusively for ECJ.
Water is the natural response to almost any stain, spot or dirt that crosses our path. I immediately grab a wet cloth, bucket and broom, or a bit of saliva when other water sources are out of reach. Sometimes even when dry cleaning would be better. In fact the first cleaning law is: “Keep dry what can be kept dry”. At least, that's what they tried to teach me in a vocational cleaning course at SVS, Rotterdam in the Netherlands.
And it makes sense: a sandy pavement will become muddy if you add some water. Better to sweep it than to try to flush the sand away. And a dusty hard floor should be dry mopped before any wet cleaning method is used. However obvious this may sound, we need to be told to think before acting by applying that powerful cleaning agent called water.
The power of water is that it dissolves salts, sugars and many other compounds. Also, it causes swelling and loosening of many foodstuffs. Even oily and fatty stains can sometimes be removed by plain water. Often the fatty compounds are emulsified in droplets. Each droplet has a coating of a natural detergent - emulsifier - which makes it relatively easy to disperse in the water during cleaning. Thus, water weakens the bond between surface and dirt.
The second action of water is to carry the dirt to the sewer. Water is used to flush dirt, in toilets and also in window cleaning and wet floor cleaning. In the case of a wet cloth, the cloth fibres are the actual dirt carrier, but the water is essential to bind the particle to a fibre using capillary forces. These capillary forces are no other than the force that keeps droplets together in a sphere or a droplet.
In short, water is good at loosening dirt and in carrying dirt to a place where it does no harm anymore, the two essential steps in cleaning. Even in floor cleaning, as confirmed by Annete Ostertag of Kärcher: “It is certainly possible to clean using water alone. As long as effective cleaning machines are used, this produces an excellent result in many applications, such as removing light soiling by water-soluble dirt.”
Yet we seldom use plain water in cleaning. Our second natural response to a stain is to add a detergent to the water. And a bit more, to be on the safe side. Indeed detergents are needed to remove heavy grease, in particular mineral oils, or on surfaces that do not wet.
Detergents lower the surface tension of water, allowing it to wet surfaces and thus to apply its cleaning power quickly on all of the dirt. Also, detergents emulsify oils and grease, releasing them from the surface and keeping them dispersed in the water. Detergents also may contain alkali to enhance this effect and attack other stains, or acids for removing chalky stains. And detergents typically contain “agents which, for example, bind lime scale in the washing solvent, thereby significantly reducing the greying of surfaces, reducing dirt adhesion to the brushes and brush head and enabling the cleaning brushes to glide better”, adds Ostertag.
Thus, detergents serve their purpose on the more heavily soiled floors. But that comes at a cost. Even the greenest and most eco-friendly detergent affects the environment. All of its components may be biodegradable and non-toxic, still a lot of energy goes into the production, mixing and transport of the stuff. And more often than not, too much of it is used.
Overdosing is a common and understandable but very foolish habit. It simply is not economic, may result in slippery floors, causes undue foaming, eg, when vacuuming the floor, and harms the environment. Moreover, detergent residue can cause streaking or film formation.
Guido Wagenmakers of Tennant in the Netherlands: “Our customers often think we still use detergent in the ec-H20 technology, because of the huge amount of foam in the water waste compartment during the first test. But this is simply due to residues that we remove from the floor. The foaming does not occur anymore after a few treatments. And flooring materials get their original brightness and become less slippery.”
Detergents should be used sparingly, but that is hard to achieve in actual cleaning practice. Wagenmakers: “We advice our customers to remove all floor cleaning detergents from the building that is to be cleaned with our technology. Otherwise the staff will keep on using it, even after intensive training.” That is how strong our urge is to add detergent.
However we have three other ways to enhance cleaning effects: time, force and temperature. We know his from first-hand experience, when confronted with a stubborn stain. In such cases, we may repeat our efforts, use hot water or put more power into it. This may be either manual power, by brushing harder, or a mechanical aid - for instance a scourer. Together with the detergents (or: chemical energy), time, mechanical energy and temperature make up the Sinner Circle. This circle was constructed in 1959 by Dr Herbert Sinner of the German detergent supplier Henkel.
The purpose of the circle is to show that the reduction of one factor (ie, by using less detergent) can be compensated for by any of the three other factors: time, mechanical energy or temperature. This is a very useful concept, although more recent research shows that this may not be entirely true. For instance, enzymes activity is ruined when using hot water. Nevertheless it is important to understand that cleaning can be improved by smart combinations of chemical and mechanical energy, time and temperature.
This applies in laundering, for which the Sinner circle was constructed. In hard surface cleaning, the use of hot water is rather futile: it is simply impossible to heat large surfaces to any degree. The cleaning time is also very limited. In manual wiping of a desk, each part of the surface is touched for much less than a second. Cleaning substantially slower would be very uneconomical.
Thus detergents have very limited time to act upon any dirt, too little to have any serious effect.
A study by the Dutch cleaning research association VSR on manual cleaning shows that the addition of detergent has little effect on the removal of stains of coffee, chocolate milk and skin fat. It was also shown that microfibre cloths were better in stain removal. This is explained by the improved mechanical action. More force is needed to move the microfibre cloth over the surface, because more fine fibres with sharp edges need to be moved over the surface. Thus the microfibre is a nice example of the replacement of detergent by mechanical action.
In hard floor cleaning with machines, extra mechanical energy is added by using microfibre pads, increasing the pad rotation speed or increasing the pressure on it. Also, one can increase the water flow to quickly remove the dirt and prevent resoiling. In traditional cleaning machines, considerable amounts of water, detergent and mechanical action are applied to be sure that the cleaning effect is always very good, even for heavily contaminated surfaces.
However many surfaces are only lightly soiled, making this approach effective but not very efficient. In many cases it may be entirely satisfactory to use little or no detergents. Tesco, a large British chain of supermarkets, enforces that its supermarket floors are cleaned mechanically using no detergent. Cleaning appears to be entirely satisfactory. Thus traditional cleaning machines waste money and environment by using too much water, detergent and (mechanical) energy.
Different floor cleaning machine suppliers responded in different ways to this fact. Both Kärcher and Nilfisk-Advance have designed machines that use no detergent, and less water and mechanical energy than is traditionally used. Both machines can be switched to a more intensive setting while performing the cleaning job. Ostertag: “The Kärcher DOSE system makes it possible to add cleaning agent to the washing water on the brush head at the touch of a button.” The Ecoflex concept from Nilfisk-Advance has a switch to go from detergent-free ‘green clean’ to ‘deep clean’, yielding a burst of 60 seconds of detergent, solution flow and increased brush pressure.
Tennant developed another concept - ec-H20 –technology that treats water electrically to chemically alter it, at least for a short time. This is claimed by Tennant to be an effective means to improve cleaning without adding detergent or mechanical action. Tennant has shown several studies that show some effect, but has never shown the comparison of exactly the same machine with the ec-H20 technology on or off. Wagenmakers adds: “The technology has been in use at many different customer sites since 2008 without any complaints. This includes several high traffic areas like Schiphol airport.”
Others doubt the value of the electric water activation. Ostertag: “Internal and external experts at Kärcher so far have largely been unable to confirm the alleged advantages of activated water. Our internal and external investigations have not yet been completed however.” Pernille Pedersen of Nilfisk-Advance adds: “We do not believe in activated water. It is a pure belief and common sense to us that for some cleaning tasks you will need to use detergent.”
Wagenmakers is the first to admit that chemicals are needed for heavily soiled floors, as well as for floor stripping and floor disinfection. “Our machines can also be used with detergent and other chemical. But we are genuinely surprised by the number of applications where no detergents are needed. Even including multi-storey car parks.”
The newest guy on the block is Activeion, a spray flask with a unit that is said to electrically activate the tap water in it during the spraying action. It is promoted with quotes like: “The activated water sprayer leaves behind no film or streaks. This means we can clean more quickly and less frequently since no residue remains". (Lorri Traylor, King County Metro Transit) While this may be very true, it cannot be ruled out that exactly the same effect is reached when using plain
tap water. Remember that it was observed that a traditional cleaning cloth with plain water works almost as well as one with a detergent solution.
Using no detergent, as argued before, has the advantage of leaving no residues. Indeed, in that very same vocational training at SVS I mentioned before, I was trained to clean mirrors by splashing a bit of water on them and cleaning them with a paper towel or with toilet paper. Works wonders! Indeed, I now believe that the second law of cleaning should be: “Clean without detergent what can be cleaned without detergent”.
And this law is valid much more often than you’d think.