Cleaning guidelines Recognized state of the art

For cleaning natural and artificial stone, the generally accepted technology is stated in the FRT guide to mineral floorings. Why is this important? According to the German Civil Code, allservice providers must comply with these standards unless another agreement has been made.The guide was developed by the European Cleaning Hygiene and Research Association (FRT) in Krefeld, Germany, led by Dr. Patrick Casper, and signed by the National Trade Guild of Contract Cleaners, the National Association of German Stone Masons and the national trade associations for concrete-based stone. Deutsche Steinzeug AG, the renowned German ceramics manufacturer, collaborated in developing standards for its field. Apart from wood, natural stone is one of the oldest flooring materials used by man. The varieties of stone and their highly diverse characteristics and surfaces are almost inexhaustible. Furthermore, there are also many cleaning recommendations for mineral floorings. Unfortunately, these often depend on the manufacturer and are not always useful for service providers (e.g. “Use warm water and soap.”). Slip resistance is also a requirement. One typical property of natural stone is its capillarity. This means that between the crystals, there are interconnected cavities. This is important to know because basic cleaning only removes those close to the surface. Classical basic cleaning can never lead to a “like new” condition. Categories of artificial stoneArtificial stone is classified according to type. Resin-bonded materials Agglomerate marble and quartz: As a rule, polyester resins are mixed with the natural stone. Agglomerate marbles consist of limestone and pieces of marble mixed with synthetic binders and cast in blocks. After hardening, it is used to manufacture panels or floor tiles. This product was formerly a low-budget material. It has lost significance since the 1980s – at least those types that resemble artificial stone. Newer varieties are very fine-grained and colorful. Their use is limited by the B1 fire classification for escape stairwells. The situation is different for quartz agglomerates, which have been on the market for about ten years. Quartz, a very hard mineral, is cast in sheets and processed. Its high abrasion-resistance has popularized it and led to frequent use. Visually, there is barely a discernible difference. Cement-bonded materials Artificial stone: The classic scrap utilization material. Pieces of rock, usually marble and limestone, are mixed with the binding element – cement – plus dyes and then laid. Unfortunately, they are usually “treated” afterwards with various substances that hinder proper cleaning. This group of materials includes cement boards, which are now back in fashion. Ceramics: The first artificial substance used by humans was ceramics. Applying heat to natural materials such as clay (weathered granite remnants) creates a new material with the most varied characteristics. But only rarely is a cleaning service provider also a geologist, a concrete technician or a ceramic engineer who recognizes the individual materials and knows how to handle their peculiarities. This is why tools exist that help practically anyone answer the important questions. Exceptions to the rule always exist, of course, but the following information is sufficient for handling 99.8 percent of all materials found. Test 1: Cleaning or finishing?Cleaning is the removal of dirt.Finishing is the deliberate application of some sort of treament. Due to missing or incorrect documents, it is not always clear how a floor should be handled. Film-creating products such as soaps, polymers, waxes and so on, leave a lubricating film on all hard stone (granite, basalt etc.) and ceramics that often reduces the slip-resistance with which the material left the factory. If water is added, a dangerously slippery – and unattractive – surface can develop. Soft stone such as marble, limestone, artificial stone or coarse ceramic products like terracotta should be gently cleaned and finished to conceal the rapidly appearing traces of use. The FRT guide states: “When using soap cleaners or stone soap, so-called soap scum develops together with the water hardness. These are usually insoluble and slowly penetrate the pores of soft stone or cling to their surface. This superficial scum can then be mechanically compacted and polished. Over time, a matte shine and light protective film develops. If necessary, the film can be relatively easily removed with a suitable basic cleaner.” However, there are also treatment products that can no longer be removed with aqueous solutions. Who hasn’t run across intensive shine products in the consumer area? Such aqueous polyacrylates are also used in professional work. If cleaning service providers are faced with floorings treated with this type of product, they need to work together with the client to find professional help for the problem. To find out whether a floor needs special care not, a scratch test is used. A cutter or carpet knife is all that is required for this fast, simple test. With light pressure, the service provider tries to scratch the floor in an inconspicuous spot (e.g. not below a chandelier). If no scratches are visible or palpable, the material only needs cleaning. On the other hand, if the scratches are visible, the material can be cleaned and finished. The important thing is not mistaking metal abrasion from the knife for a scratch. Finishing generally leads to a deeper, more desirable hue. Test 2: Acidic or non-acidic cleaning?Cement residue can be removed either mechanically, using abrasion, or chemically using an acid. The scratch hardness, however, says nothing about acid resistance. Even some very hard basanites react to acids. Every acid also has preferences and characteristics; this was discussed in a previous article (rationell reinigen 4.2005, page 34). The acid resistance of mineral materials is tested with amidosulfonic acid, the standard acid used in building cleaning. An eyedropper with undiluted amidosulfonic acid is used to apply one drop on an inconspicuous spot on the floor. If it foams, grime can only be removed mechanically from the water or cement residue. Be aware, however, that some stone does not foam, but reacts by changing color! This is why the spot must be thoroughly rinsed and dried. Critical materials include green serpentinite or black basanite, which is often incorrectly designated as basalt. The guide also points out that removing cement residue is an additional service that must be carried out by the floor layer – not part of final construction cleaning. Test 3: Is there a damaged “dirt polish”?The slip test is a practical method that clarifies many problems. Everybody has seen the following at one time or another: Rub marks from washers on ceramic or granite; water spots on black basalt or fine stoneware; granite that has been dulled from amidosulfonic acid. The common cause of these is ‘dirt polish’ that is damaged. ‘Dirt polish’ refers to hardeners spread during cleaning. Surfactant residues – which can remain after any cleaning process – adhere to the floor. The cause of this – in addition to overdosing – is ‘low-aqueous’ cleaning. The surfactant residues on the floor, the lime from the water and not to forget – the dirt as well –, all join to form a very sticky yet thin layer that can even be polished. Hence the name ‘dirt polish’. This layer can almost never be eliminated with a basic cleaner; in almost all cases, only the uppermost layer is removed; it is then replaced by the basic cleaner with a new one. Dirt polish can be removed with microfiber pads and clear water – but it takes time. Faster methods must be examined on a case-by-case basis. Carrying out a slip test is relatively simple. A little non-carbonated mineral water is applied to the floor; approximately four minutes later, the spot is rubbed with two fingers. It the spot feels slippery, detergent residues are the culprit, because no natural or artificial stone flooring can be superficially dissolved and smeared by water. Stain removal and moreThe FRT guide has much more to offer than these three tests. Its stain removal concept for natural and artificial stone has been developed over decades of experience by the participants. Images of damage with explanations round out the guide. The guide is often used as a basis for expert appraisals and to assess whether a cleaning job and the method used meet the recognized technological rules of practice. This is also true for tenders. The sentence “Maintenance cleaning must be effected in such a way to preclude the need for basic cleaning” does not meet the generally accepted trade practices as required by the BGB, and it can thus be considered void in the event of a lawsuit. This is why the FRT guide is a must for every object manager, division manager, or master and technician. It can be obtained free of charge from the Europäischen Forschungsgmeinschaft Reinigungs- und Hygienetechnologie under info@frt.de or by telephone under +49 (0)2151 8210110. Usually, the guide is also available from the guilds. Herbert Fahrenkrog | markus.targiel@holzmann-medien.de

Cleaning guidelines Recognized state of the art

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