Materials

Irremissible steel

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Loved by designers, demanded by consumers, requested by producers for its characteristics of resistance to wear and aesthetical outcome. But the beauty of steel components is counterbalanced by the difficulty in keeping them clean and glossy.

Vivien Reimbelli and Valentina Zambello

HA05_TECH_REIMB_APEFine, very fine, nowadays irremissibile, stainless steel lords it in all household appliances and not only. Mandatory choice of contemporaneous designers, it has gradually replaced other materials like wood and stone in kitchen coatings to the extent of coating the majority of household appliances, and in particular those used in the kitchen, due to a logic of aesthetical coherence. The trend origin can be partially identified in the attempt of joining domestic appliances with professional ones, which are exactly made of steel owing to the needs springing from continuous washings and sanitizing that would badly suit enamelled coatings and that would show the signs of such an intensive use in short time. Certainly stainless steel features very interesting characteristics of resistance to wear and it might represent the “final solution” to rely on a material with almost endless service life and providing several advantages in productive phase, like the simple workability, the excellent resistance to mechanical stress, the easy welding and the possibility of excellent level finishes. The limit of the specific weight is not a highly influencing element, considering the small sizes of household appliances and of furniture surfaces, not needing to be displaced. Besides, the affordable cost, for instance lower than aluminium’s, makes it a material usable on large scale even in not particularly thriving times.

Clouds on the horizon
Everything is ok, then? Not exactly, since stainless steel (although stainless steel is a generic term, since there are several types)HA05_TECH_REIMB_CORPO shows some practical management difficulties.
First of all cleaning. Even if it is easily washed, to maintain a pleasant aesthetical look it needs successive polishing operations, often carried out with apposite products to avoid the formation of that annoying surface patina that, if it does not bother in a professional kitchen, it is not desirable to see inside the home walls. The causes of this patina can be both the use of detergents containing bleach as well as a quite hard water, with limestone, which, by drying, exposes the salts contained in it under the form of opaque stains. Actually, all the times that we wash a surface, we should proceed to a successive polishing phase with specific products and, eventually, with grandmothers’ remedies (which today we would define “green”): white vinegar passed on the surface and a successive pass with dry cloth to remove it and to leave a glossy surface.
Bigger problems will arouse with the carbon residues on hobs, like the feared oil drop that percolates and burns due to the heat effect and leaves a visible trace, of milk-and-coffee colour, which if not removed will tend to darken more and more, becoming also difficult to remove and the even excellent wine vinegar will not be sufficient anymore.

Steels for all tastes
HA05_TECH_REIMB_FORNOWithout going into the details of excessive technicalities, it is worth reminding that there are different typologies of stainless steels, with completely different mechanical features and resistance corrosion properties. We often take for granted the resistance to corrosion of steel, which is given by the chromium contained in it (but in some alloys also manganese, molybdenum and nickel are present), which actually is a so called passive resistance, since it is chromium itself that oxidizes thus creating a very thin surface patina that protects the underlying layers. The chromium price neatly influences the stainless steel price and consequently its content defines cost and quality of the final product. The result is that determinate components can be not totally resistant to corrosion, as perfectly know those who live in areas close to the sea, where, especially in windy days, saltiness becomes volatile and in time it can make some unpleasant oxide streaks appear (often in junctions and in welds) that certainly do not contribute in conveying a sensation of quality in products. The parts immersed in hot water where are generated electrolytic currents (the banal kitchen salt is sufficient to trigger them) and anyway exposed to heat are the most subjected to corrosion and, concerning them, utmost attention will be paid in the choice of the stainless steel to be used, to avoid incurring into showy oxidations in short times. Stainless steels are catalogued with the AISI initials and it would be opportune to provide consumers with a legend that, besides identifying the typology of steel used, explains its characteristics and motivates the reasons for choosing this or that steel, thus HA05_TECH_REIMB_FRUSTEtransferring the expertise of the company that often does not tend to communicate those technical specifications that, read from the consumer’s point of view, might instead be interpreted as a demonstration of its know how value. Just as it happens in the wine world, where raw materials and processes are expressed to ennoble the product and communicated to consumers to transfer the competence value and to convey the perception of the commitment lavished in the product implementation, ennobling it and justifying its price. Concerning this, it would be certainly interesting to create a sort of classification of steels from the qualitative, and not only technical point of view (origin, composition, characteristics), communicating qualities and explaining the choice for that determinate application.

Where we like stainless steel
It often happens to find appliances, in particular ovens, with the control dashboard built-in in a delicious stainless steel plate, of great elegance but unavoidably undergoing the constant contact with the fingers that operate controls. If a simple fingerprint is sufficient to stain steel, just imagine what will be done by the fingers of the emerging Masterchef who is preparing its ambitious recipes and who, before operating the controls, will have handled foods: he will leave clear fingerprints that, if not rapidly removed, will be then difficult to clean. Not to miss anything, we will have also a fine glass insert competing with steel to exhibit any kind of stain and halo.
Likewise, the controls of blenders and mixers and the areas surrounding them will show all the signs of our work and will not need HA05_TECH_REIMB_MANOPOLAan inspection in CSI style to detect the course of the actions accomplished. Built-in knobs and keys will make the polishing activity very difficult and at the same time they tend to create some really unpleasant accumulations of oxidation and residues that are clearly visible, due to the “mirror effect” created by steel and to the bright colour.
Besides, steel controls, if wet or greasy, tend to become particularly slippery, thus making the use difficult.
Also the simple storing of the household appliance at the end of its use unavoidably involves a contact with hands and if the body is coated with steel, fingerprints will remain well visible and we will find them at the successive use.
Even if steel provides good mechanical resistance, the contact surfaces with other tools will be easily scratched and in short time what appeared like a very elegant metal surface will show lots of scratches that annul the initial beauty of the material.
Very diffused is the problem concerning cooking hobs where the handling of the cast iron grids scratches with extreme facility the hob itself and, frankly speaking, it is not always possible to avoid, during their mounting and dismounting operation, slight settling movements that leave even very evident marks.

Where we like stainless steel
Certainly in household appliance accessories. In mixers we often see accessories such as hooks and various die cast aluminium components, sometimes enamelled to make it more …appealing, or even made of plastic. Result? Failures of the parts or creation of “backlashes” in couplings. In particular, enamelled elements tend to see the enamel disappear over the time in the points subjected to the highest friction. Some time ago it happened to see some dies for pasta made of synthetic material, with the only mobile parts made of steel: failures were endless. Also steel tanks show better resistance to wear and easy cleaning and the same observation is true for the mobile parts of blenders and similar. Definitively, all parts subjected to wear can benefit from a stainless steel structure, rather giving up coatings, because, if it is true that they are aesthetically elegant, they do not provide practical advantages.

We can give it up
Someone, especially the producers of built-in ovens, will distort the nose while thinking of giving up steel but it would be really interesting to consider other materials, and not only glass, which determines the same cleaning troubles. It is also worth saying that, while in the past steel was essentially prerogative of high-end products, we currently witness a sort of “over-exhibition” of this material that, even remaining in line with the modern aesthetical canons of furniture, starts becoming massively diffused.
In times of great attention to energy saving issues, it would be advisable to research thoroughly materials able to propose a good insulation coefficient and to allow reducing the dispersions and the heat transfer, thus optimizing the machine performances and justifying the choice of giving up steel in favour of a “greener” approach that would anyway return to the users’ pockets in the form of economic advantage.

More information
It often happens to read in forums some complaints about the product but if we go into the details we can understand that it is oftenHA05_TECH_REIMB_RUGG negligence, that’s to say, starting from the assumption that the damage has been made on an item owned by writers, we are induced to think that they are scarcely informed about the cleaning procedures on steel surfaces. The user often proceeds as usual with products and methods that are fruit of hearsay or of habit and that are not suitable for that determinate material. It is also true that there are often aggressive cleaning products not reporting (at least not clearly) the use limitations and the unaware user employs them believing to obtain a good result; when he attains the opposite outcome, he tends to cast the blame on the validity of the material composing the appliance. What to do? Certainly a bit of back-to-basic, not taking anything for granted and diffusing opportune domestic housework education, accompanying the appliances with not only essential, but also clear and exhaustive suggestions for cleaning, and maybe with some “smart” advices to obtain good results without much effort.
Sector novelties
They have recently presented a new technology applied to steel through the use of nanotechnologies that allow obtaining a surface that prevents food residues from adhering. This technology has been applied to cooking hobs and to other household appliances, making them more resistant. It obviously remains the need of a cleaning and polishing action but it limits the deterioration and facilitates cleaning operations for hot parts. This makes us hope in the possibility of always finding new solutions aimed at treating the stainless steel surface in such a way as to make it free from the above mentioned hindrances.

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