VITREOUS ENAMEL STEEL IN ARCHITECTURE AND RANSPORT INFRASTRUCTURE
Pinuccia Alemani, Francesca Iob

Company profile
SMALTODESIGN srl. was established as the department involved in the building sector of Smalterie Lombarde spa (founded in 1941); thereby combining the ancient enamelling craft with the more recent applications of enamel products in the building sector. Thanks to its intrinsic features the material is ideal for use in a variety of building and furnishing contexts: in the hospital sector, the naval sector, townscape, and the transport sector (underground, airports, motorway toll points, railway stations and tunnels) and furnishing elements, as well as in the enamelling of all kinds of domestic and industrial products (sinks, hot plates, exhausts, ovens, stoves, exhaust pipes etc). SMALTODESIGN Srl has undertaken over a 100 architectural creations, overseen by the leading architects of the time: Gregotti, Piano, Forster, Zanuso.

Reference standards
In its production of panels for architectural use the following standards are used: UNI 9757 for Italy, as well as the British BS standards and the German DIN standards. However they will shortly be replaced by the European EN 14431 standards formulated with the WG5 workshop comprising the representatives of the leading European countries.
For overseas projects the standards laid down by the American Porcelain Enamel Institute are followed (PEI) which have become an important point of reference in particular sectors (panels for architectural applications for example) in the absence of any specific national standards.

The enamel steel panel market: international situation and prospects
We have noted a growing demand in recent years for the use of enamel steel in public areas, not only restricted to the odd column or corridor but as the complete covering material of an entire station.
This undoubtedly highlights an ongoing urban redevelopment trends both involving new buildings and the renovation of old ones.
These public areas (stations, underground stations, airports and ports) thereby take on a new dimension as a “place of meeting and passage” that is complete and pleasant and stimulating in terms of atmosphere.
In order to meet the growing “mobility” demand (one has only to think of daily crowded railway stations), State Authorities and local bodies aim to transform old and dilapidated areas into truly attractive places. Thereby the need arises for the design of closed and fully integrated areas such as a railway station, that is also fully equipped with all facilities such as a shopping centre, beauty farm, restaurants, bars and supermarkets etc, where the passenger can combine business with pleasure, in much the same way as airports.
The “Hundred Stations” and “Great stations” projects in Italy aim not only to embellish decaying railway structures but also to expand the range and scope of the services offered.

This has led to the need for the use of materials with specific features, they need to look good, be functional, safe, resistant to time, and easy to maintain and clean.
Such projects are often commissioned to leading architects (such as Piano, Forster, Aulenti etc) who rest their prestige and fame on the use of prestige and quality materials which meet all the compulsory standards in terms of: fire safety (class o), maintenance ease, corrosion resistance, anti-graffiti quality, anti- breakage etc.
Vitreous enamel possesses all these qualities and has therefore been strongly featured in more recent architectural projects.
We shall cite some recent applicative examples using both our own enamel panels and those produced by other enamel companies worldwide, which demonstrates the widespread diffusion and application of vitreous enamel steel throughout the world:
The London Underground: the home of Escol
The Berlin Underground: since the reunification of the city, a re-development project is underway of all the old stations using vitreous enamel.
Budapest Underground: the city is having a complete makeover since its entry into the ECC, and several stations are feature vitreous enamel coverings
Milan and Naples undergrounds in Italy
The Madrid Underground: which boasts a long tradition of vitreous enamel coverings
The Singapore Underground: The Clark Quay station
We shall now consider the different points of view in relation to the choice and use of enamel steel.

THE REQUIREMENTS OF PUBLIC ADMINISTRATION BODIES
A material that is functional, pleasing to the eye, safe and lasting though time (it is outrageous that sometimes newly concluded projects already need material replacements and maintenance) in order to be sure of achieving public consent and approval.

WHAT THE ARCHITECT REQUIRES
All the above, as well as the need to choose a material that in some way identifies him and bears is mark, and designer signature, for example in the use of a customized colour, that may be unique, personalized or subtle, or of a particular style. This is all possible using vitreous enamel.

WHAT THE GENERAL CONTRACTOR REQUIRES
The General contractor is primarily interested in a material that is easy to use on site, and which easily adapts to evolving work stages, which can be replaced quickly in the event of any design errors and above all a material that can be delivered fast, as well as a low and competitive price.
This brings us to the downside: the production process of the enamel panel is lengthy as compared to other materials and much more costly. It is medium-high priced and often the price factor is the only thing considered without taking in account the long-term advantages in terms of duration through time and resistance. Another negative aspect is the fact that in the event of incorrect relief the panel is difficult to adopt and therefore not suitable for re-use, thereby making it necessary for a new panel to be produced.

PRODUCTION REQUIREMENTS
1. Standard panels: possibly avoiding special formats, which would require furnace balancing studies and the construction of suitable tools.
2. Regular production scope, which can be programmed over the medium-long term. This however is not always possible unfortunately, because the panels required for a project tend to follow the life of the project itself and therefore need to be produced and installed almost in realtime, given that the covering is always the last aspect to be considered. To counter this it is important to have flexi-hour work teams, which however always need to be highly qualified.

Conclusions: MARKET OPINION
We are unfortunately aware that vitreous enamel tends to be known as a fragile material, that is difficult and costly to replace, so that if there is no specific “culture” of vitreous enamel use it is hardly ever included in the specifications.
There is therefore a need to make a committed effort to ensure ongoing promotion of the material particularly focusing on its great durability through time.
The correct application of the standards both during the production stage (for example efficient pickling ensures a good level of corrosion resistance) and during the installation stage (by instructing the operators on how to correctly handle and assemble the material), which makes an important contribution to the end result. For example the colour differences within tolerance level limits, as envisaged by the standards, does not jeopardize either the aesthetic appearance or the quality of the material.
By efficiently educating the customer on the specific features of the material, ensures that we can avoid any complaints or misunderstandings on delivery. A specific example being: the orange peel effect that is considered as being a defect in many Asiatic countries, is considered as being a specific characteristic aspect in many other European countries. While the standards consider it asbeing a “characteristic” to be agreed on between the parties concerned.
The market space for the material is still limited, as is the actual number of producers that actually follow the standards in relation to vitreous enamel panels for architectural use, but promotion and good quality are the best ways of enhancing the image of the material on the coverings market.

Road and motorway tunnel covering
Tunnel covering with vitreous enamel steel panels: the contractor’s point of view
The tragic fires in the Monte Blanc pass (between France and Italy) and in the Tauer Tunnel in Austria and in the Gottard tunnel in Switzerland have brought home the issue of road tunnel safety.
In those countries more attentive to safety issues such as Great Britain and France, the USA, the Far East and Oceania, the preferred tunnel wall covering system is one that uses “vitreous enamelled steel panels”. A comparison of various covering materials (aluminium, fibre-concrete, cis varnishing, vitreous enamel) clearly shows that this last clearly leads over all other systems.
Regulatory standards consider vitreous enamel as being one of the most suitable products for road tunnel re-facing. As these enamel panels ensure duration, assembly ease and reduced maintenance needs.
Thick steel panels specifically treated on the two faces, on the edges and at the hanging slot points ensure: improved and uniform illumination at lower costs because they are photo-reflective; energy savings in gallery ventilation, effective control against the water that leaks from the walls, the possibility of (silk screen or transfer) printing of architectural motives or signs to indicate emergency exits or assistance points directly onto the panels, easy integration with cable ducts and technical services, greater cleaning ease of the vitreous surface (graffiti can also be cleaned away easily with solvents); resistance to pressure and depression caused by traffic; greater acoustic comfort. Motorway tunnels require covering of the vertical walls or the entire section, which helps to protect the tunnel itself by creating an inter-space, of varying depth between the walls which can be coated with a concrete layer or left rough (in the case of visible rocks). Not only this, but also these panels have a technical-illumination purpose, and can be fitted with system panels, smoke control elements, luminous leds and graphic symbols for emergency signs. It also acts to protect the rear concrete structure although it cannot be considered as a true safety barrier, the resistance to vehicle impact of the metallic structure and vitreous enamel panel system has still to be tested, however the system is without doubt capable of absorbing impact to some extent together with other safety devices.

The producer’s point of view
A comparison of two tunnels: project for the covering of the piers compared to the covering of the entire calotte
We have supplied coverings for the following tunnels: Piedicastello (Bolzano - 1999), Funes (Bolzano - 2002), Saltash (Plymouth – Cornwal l- UK- 2003). We take as comparative examples the Funes Pier covering and the entire calotte covering of the Saltash tunnel.
The covering of the vertical walls of the Funes tunnel (near Bolzano), the production method of which shall be analysed further on, has been designed in such a way as to create a metallic structure that supports the net cut panels and curves them to follow the curvature of the tunnel walls. The structure consists of a series of long wedges that intersect inside the reinforced concrete wall leaving an inter-space of a depth of about 20 cm. Aluminium uprights are fixed to the wedges, which act to hold and support the panels. The features of this kind of covering is firstly the simplicity and resilience of the panel (a thickness of 2.5 mm having been determined by the need to guarantee resistance of a pressure of 60 kg per m2), secondly the inter-space which is suitable for containing the tunnel systems, and to protect the concrete covering of the tunnel walls.
The Saltash tunnel near Plymouth (Cornwall) has very different features. The tunnel is of approx.
800 m in length and needs to be totally covered by panels as it subject to consistent water dripping and often true water influxes. A system was therefore developed of juxtaposition of the 7 panels that cover the vault in order to impede the passage of water inside the tunnel vault. This has been possible thanks to the design of horizontal edges bent in such a way as to convey the water flow, the interconnection between panels has been designed to ensure that the water is able to slide away as fast as possible to the bottom of the tunnel which contains the discharge piping. Each panels has two folds at its horizontal edges that permit the interconnection between panels, while the vertical edges have a net cut and are subsequently curved by the centring of the sub-structure.
The colours used also depend on the lighting technique input to be provided by the panels to the tunnel: the first row of low panels are grey in colour, then there are two rows of large white panels and two rows of large black panels. The panels can be classified into 4 types:

Type A – small panel 1200x1200 – grey – the lower boxed fold has drainage holes of 15 mm in diameter.
Type B - panel size 1200x3025 – white - this type features sheet metal squared sections on the back of the panel, also enamelled which act to convey the water, and know as drip sections. This aspect has meant that particular care has been taken in the production of part B, the drip sections fixed by means of light spot-welding.
Type C: panel size 1200x1340 – black – a connection element between element B and the tunnel vault element. The lower edge of this panel is perforated (diameter 5 mm) for water discharge.
Type D: panel size 1200x3306 – black, this panel features 2 folds of 45° at a distance of 80 mm from the edge, which create a kind of collection hollow of 5 mm in depth. When the water escapes from this hollow it slides over the side sections, the folds of which are also perforated (5 mm in diameter).

Further road and motorway applications (sound-deadening barriers and motorway toll point covering)
Sound deadening barriers
Such barriers are increasingly frequently applied along road and motorways in view of recent legislative trends, which are increasingly focused on making road travel more pleasant for the traveller and increasingly environment friendly. Both new and renovated infrastructures increasingly incorporate sound deadening devices. The legislation regulating sound deadening material envisages the use of various materials, which are all degradable to a greater or less extent: wood, cement, a blend of substances, painted aluminium and painted steel. There is a choice of the classics sound-deadening stave which is assembled between double steel t-shaped elements or the tunnel covering panel made of totally or partially micro-perforated enamel steel. Motorway toll points
This study relates to a pilot project put into application on the A4 motorway (Verona – Vicenza –Padua - Venice section) at the East Verona entry/exit barrier.
The operation consisted in covering the reinforced concrete “New-jersey” guardrails that delimit the entrance and exit areas of the toll point. The aim was to propose of novel way of appreciating the New Jersey enhancing its long-life and beauty by covering it with vitreous enamel steel panels. 3 elements were designed; the side covering known as the “mini-skirt”, the hollow light holder and the completion dome at the beginning and end of the bumpers. The mini-skirt is in fact a piece of press-folded 20/10 sheets, which rests against the new-jersey rail and secured by means of M8 oval-headed screws. Special indented holes have also been made on the piece so that the screw enters completely with no projection. The upper and side edging forms a compressed fold, to ensure the excellent aesthetic look of the element without having to use any decorative elements which do not last.
The light holder is a very particular element, made of forged press-bent 15/10 sheet and contoured to fit the light holders made of other materials, it takes the form of the guard – rail and its recessed sections is used to house the “turtle” of the typical lights marking the entrance to the toll point. It is a highly complicated element to produce in vitreous enamel steel, as to ensure the full cover of the piece it is necessary to partially use a ground immersion enamelling process and in part the traditional humid covering process. The element is light and easily installable and the interior houses the electrical power points that feed these “turtle” (L-shaped) lights. This light holder is fixed on the wedges in the concrete using screws and the different elements are horizontally aligned. This is possible thanks to the boxed folds at the end of the panel, which as well as enhancing the look of the element improve the alignment process when laying.
The dome is the connecting element of the two rows of new –jersey rails, which contain the toll structure. Made of 20/10 sheets it follows the same contour as the mini-skirt and is calendared.
The side edges have a compressed fold while the top features an arched boxing welded to the rest of the piece. The dome is completed by the overlaying of the lights, which indicates the presence of the New Jersey rails to the driver.

Architectural applications: the versatility of the vitreous enamel panel
Vitreous enamel panels are highly versatile in architectural applications: they can be used both in new building work (ventilated facades, façade buffering, façade covering), and in the renovation and modernization of existing buildings. Vitreous enamel coverings offer the architect a wealth of aesthetic and functional scope. The façade or the portion of the building concerned may be designed according to the plastic effect required or according to the fixture of the panels to the existing structure. These panels can be used to replace walls, partitions, the doors of technical compartments, false ceilings and perforated panelling for any conditioning or ventilation systems that may be required. The panel thereby becomes a new applicative element in each new project, as it may be adapted to the specific building requirements and needs.
Although the tendency is that of standardizing the composition of the faces, there is unlimited scope for the production of elements of particular shapes, calendared pieces, or boxed or elliptical section pieces. The panels used in architecture must be produced with the greatest care in all production stages; the appearance of the panel must be free of any kind of defect. Last but not least is that designers for the surface quality, its brilliance, and the infinitive chromatic potential that it offers particularly appreciate the material. The modern transfer printing techniques available today provide the possibility of writing, drawing or decorating the panel itself, with a host of graphic options and to the highest level of photographic resolution.

Vitreous enamel in public transport infrastructures: airports, underground, railway stations
Thanks to its high level of mechanical resistance vitreous enamel and the features already citedabove it is the ideal material use for in public settings characterized by a fast and consistent flow of people, in which accidents such as minor collisions or vandalism are common and which would damage any other material permanently; and important in areas in which easy stain removal is essential, in the case of graffiti or the outbreak of fire. Making it particular suited to use in those public areas dedicated to public transport; airports, underground stations, railway stations. Another important advantage of the material is that it is highly versatile and can be adapted as necessary.
Vitreous enamel steel is not only a pure covering panel, it also acts as a container and can be used as a frame, counter, door, technical compartment or casing. It can be either fixed, sliding, nonmovable, opening, or have locks, ventilation grating or micro-perforations.
We shall hereby outline the pilot projects and the most significant applications, which highlight the intrinsic versatility of the material.

Airports (Linate, Malpensa)
Linate Airport
A job that we handled a few years back; 15/10 sheet columns in two semi-shells, coloured dark grey. They contain the supporting pillars made of steel and serve to protect them in the event of fire, and they also contain all the user points leading from the floating floor to the false ceiling; suchas piping and electrical cables.

Malpensa airport
We prepared a sample range of interconnecting covering staves for the interior of the terminals of Malpensa airport. The problem relating to terminal interior coverings was this: staves were present made of thick frosted glass, which are secured by metallic spiders. With time the glass tended to break at various points, the stave therefore shattered also causing a risk of injury to the users. The staves are made of 15/10 sheeting with a width of 260 mm and a height of 2400 mm, they are boxed at the sides (40 mm edge) and the upper and lower edges are clean cut. They are joined at the bottom to the pre-existing skirting element and at the top they join the recesses in the false ceiling. The fixture system of the material to be replaced is therefore maintained, the new stave being light and resilient and in four different colours, 2 matt grey shades, a metallic silver colour and a dotted aquamarine shade specifically devised to brighten the dull sequence of grey shades which are a feature of the various terminal covering materials already present.

Underground stations (Milan, Madrid, Berlin 1, Berlin 2, Budapest)
Vitreous enamel steel is undoubtedly a highly appreciated material used in underground stations throughout Europe. We have been responsible for the covering of underground stations ranging from Naples to Milan, Madrid, Berlin and Budapest.

Railway stations and subways
The Railway station in Minsk
The new Central Station complex was completed in 2002 in Minsk, the capital of Byelorussia, and one of the most important Moscow - Paris interconnection points.
The building extends over a surface area of 32,000 m2, with the capacity of holding a total of 7,000 passengers in transit at the same time. The intensive use of the building meant that the designers had to give the greatest attention to the finishing material used, whilst ensuring that they were both resilient, resistance and of pleasing aesthetic appearance. The architects and the contractor, after examining scores of various possibilities decided on vitreous enamel and stainless steel. These materials having the advantage of highlighting the architectural design of the interiors and facades.
While vitreous enamel steel came top in the finishing material competition.
In terms of colour vitreous enamel coverings were used in a different colour for each storey. The basement is therefore in dark red, the first and second floors in dark red and the fourth storey yellow. Thereby making all the storeys different and individual. This detail is extremely important for a station building, as the passengers need to be able to immediately identify the various areas.
This method has proved particularly successfully in the luminous central section, as the colour shading ranging from dark red to yellow helps the passengers to immediately identify the various areas. The emotive environmental perception is aided by the fact that the station roof has been capped with a glass skylight. The combination of the light blue colour of the glass skylight and the yellow of the pillars and the wall sections, which change colour according to the storey, gives a light and happy note to both the interiors and the external façade of the building. The relationship between the architectural structure and colour is very important, particularly in view of the dreary and often overcast climate that predominates in Byelorussia.
The Byelorussian builders also highly appreciated the assembly system, involving a sub-structure, which permits the fast and easy positioning of the vitreous enamel panels. The resistant and resilience of these panels, continue to remain the key advantages of this material, and the fact that once built the structure requires no subsequent maintenance.
The architecture of the Minsk station is therefore unique in terms of the architectural style of the façade and the organization of its internal areas.

Prototype of covering panels for rail subway for the Italian rail company
The contractor wanted a system developed for the covering of railway subways, with specific features and which, once tested, could be extended throughout the national railway network, as a means of renovating the existing railway station structures. The starting point was the choice of vitreous enamel steel, which was made after an exhaustive series of tests and trials on the various material options. Having determined the intrinsic features required (lighting technique potential, durability, abrasion resistance, mechanical resistance, fire contact resistance, and easy graffiti removal) of the enamel material, the possibility was analysed of using a modular panel of 1m x 1m in dimensions, with a class 0 fire resistance, and free of counter-plating, made of 15/10 sheet and with the dual possibility of opening by tilting from the top or the bottom, and which was totally removable. Two modular sections overlap each other and cover the full length of the subway in question; there must be no more than 10 cm between the front of the panel and the rear wall surface. The rear the covering houses wiring systems which need to be immediately repaired in the event of any problems, this is why it was important that the panels could be opened and removable throughout the entire length of the subway. The panel needs to be able to open out by 90° at thetop and 50° at the bottom. The panel needs to remain open during maintenance and this is why a steel section of circular section was developed, which can be tilted from the interior and be keptopened by fixing it in a slot on the boxed edge of the lower part. The boxed edge at the top alsofeatures two laser-cut bayonet elements integrated with the panel, which rotate on a steel pin,which permit the rotation and removal of the panel. The pin is secured to L-shaped steel elementsdirectly fixed to the wall by means of wedges. It is also necessary to bear in mind the problems related to public contact, and to ensure that the panels can only be opened by authorized personnel, to prevent the risk of vandalism or injury due to contact with power systems. This led to the idea for the incorporation of a series of very fine vertical and horizontal joints making opening impossible by anyone. With a 3 mm vertical gap and a 5 mm horizontal one. Particular care was taken in the development of these joints, to prevent the accumulation of dire also. The 5 mm joint isonly 15 mm in depth as an integrated wing section has been incorporated on the panel, which is only visible on the top edge of the same. Sealing elements were totally avoided due to their poor durability and low fire resistance and tendency to generate toxic gases on contact with flames. The panels can be opened with large rubber sections after the removal of a rod which fits into the interconnection between the vertical and horizontal joint and which can only be removed after the deactivation of a magnet behind the panel. After perfecting all the various functional aspects of this subway panel, holes were added for the fixture of luminous signs used to indicate the platform numbers and other service notices. The coloured strips created using a traditional silk-screen printing technique.