Extracts from the magazine "Hot Dip Galvanizing" are given below. To read the whole magazine click on the front page picture to the right.


Hot Dip Galvanizing Magazine 2 2015


Formosa - Amphibious House (By Iqbal Johal)


In many ways the house designed by Baca Architects and Techniker is ordinary – triumphantly ordinary. It’s an elegant ordinary house with a pitched roof structure and concrete basement. The industrial weatherscreen skin of zinc shingles wraps the glazed facade to fully exploit the magnificent views of the River Thames. It is the views that hold the secret to what makes this house so special and it is what lies beneath this house that makes it extraordinary – it is the UK’s first amphibious house.


ts special position on an island in the Thames means that the downside of those spectacular views is that the house sits in Flood Zone 3b, classified as Functional Floodplain. Planning permission could only be granted for a new structure, to replace the dilapidated existing building, by demonstrating that it can deal with the inevitable floods – a floor level 2 metres above ground level was required. A new house would need to be either flood resilient, to cope with flood water entering the building, or flood resistant, preventing flood water from entering the building. The amphibious house is a unique solution that will rise and fall with the floodwater, and so will never be flooded internally. Water can occupy the footprint of the house as if it was not there – the water simply sits beneath it.



Baca Architects are specialists in waterfront and water architecture. They apply award-winning research to find answers to the threat posed by flooding, designing accommodation that interacts intelligently with water. Techniker, under the direction of Matthew Wells, has a reputation for non-standard structural design, they approach design challenges with imagination and a holistic understanding of architectural aspirations. Amphibious houses have been built before, typically on mini piles, but not in this country and the design team felt the problem was not insoluble. To create an innovative house with a means of raising and lowering itself should be relatively easy based on Archimedes’ principle. In fact with this amphibious house, Formosa, the design team’s first solution was for a house on a steel pontoon. But then, explains Wells, “We started to investigate what could be done with an ordinary house”. The house was given a waterproof concrete basement, the equivalent of a ship’s hull, and positioned within a concrete tank as a wet dock. Guide posts or ‘dolphins’ are required for when water comes into the dock as the house is then buoyed up. Two waterproofing systems are used to ensure the basement hull is watertight: there are both internal tanking and waterproof concrete. The concept for Formosa is a free-floating pontoon set between four galvanized steel dolphins. Permanent vertical guideposts allow the house to rise up by 2.5 metres, more than enough to cope with an extreme flood event. Flexible pipes allow all services to remain clean and operational in the event of a flood. Inhabiting both the flotation unit and the roof space has enabled the architects to squeeze in three storeys of accommodation in place of the existing single storey house within the maximum height allowed by the planners. The result is an ‘ordinary’ house in which the only real additional cost comes from the construction of the two foundation systems.

Hot Dip Galvanizing Magazine 1 2015

University of Turin (By Iqbal Johal)

Designed to create a traffic-free oasis in the heart of a city plagued by congestion, the modern campus for Turin University has definitely made a statement. Since the 1990s, the university of Turin has gradually moved all of its faculties to a new campus situated on former industrial land bordering the River Dora. The new campus was recently completed with a master plan by Foster + Partners and realised by local architect/engineers ICIS. Who to their credit adopted all of the original Foster design concept. The campus houses faculties of law and political science along the edges of a triangular plot incorporating a modern interpretation of the traditional cloistered quadrangle,formed of two linked buildings, unified by a single roof canopy and arranged around a central courtyard.

The new complex has had a significant impact on the cityscape of Turin trans-forming the nearby river into a focal point and established important links with the city centre and surrounding road network. It has become a new landmark for Turin, particularly as a result of its large tensile roof structure which can be seen from across the city.


Hot Dip Galvanizing Magazine 4 2014


Sport facility in Mendizorrotza, Spain

Modulating solar gain (By Javier Sabadell)

The new sports facility for Mendizorrotza is located in Vitoria-Gasteiz, the capital city of the Spanish Basque country and was designed to be both energy-efficient and climate-friendly thanks to its architectural coherency and the use of semi-transparent solar modules.

Constructed from a framework of 1,000 tonnes of galvanized steel which supports the glass shell, the building appears to float on top of its concrete base. Nevertheless, architectural weightlessness is not the only unique characteristic of this striking building: the municipal building owner also wanted to send a clear message on sustainability. Vitoria-Gasteiz ranks as one of Spain’s pioneers and won the European Green Capital Award 2012. “Our goal was to integrate all of the solutions into one rational design that would significantly lower the power consumption of the sports complex,” explains Fernando Bajo Martínez de Murguía, the Spanish architect, planner and site manager from Vitoria.


With a total of 9,702 m² of floor space, the indoor swimming area houses a children’s swimming pool along with an Olympic pool which contains a submerged pontoon providing movable partitioning. In addition, several other facilities for competitive and recreational sports are spread across various floors.

The design also includes a double glazed climate control system that serves as a thermal air cushion to modulate solar gain. To utilize the concentrated solar energy that is generated from the long south-facing facade, 56 semi-transparent photovoltaic modules have been integrated into the facade. The modules generate an estimated annual power output of 6,450 kilowatt hours (kWh). In terms of the Spanish energy mix, this means a reduction in emissions of roughly three tonnes of carbon dioxide. In addition, the semi-transparent modules also offer shading from the sun and thus help prevent the halls from overheating, in addition to conserving the energy needed for cooling and lighting.



Hot Dip Galvanizing Magazine 3 2014

Precious Metal Association, Baden-Wurttemburg

Wrapped in Gold and Zinc (By Holger Glinde)

Schwäbisch Gmünd in the state of Baden-Wurttemburg has been home to producers of gold and silver handicrafts since the 17th century. The new building for the Precious Metal Association has been designed to help reinforce the importance of this craft to the city and create a visible landmark.

The new home for the Association will cater for special events linked to the industry as well as a jewellery store, exhibition and presentation space. Inner simplicity and external elegance characterise the design by Isin Architekten. The core of the building consists of a 19 x 19m cube of reinforced concrete. Gold coloured panels wrap around the concrete to give it a jewell-like finish. The facade is randomly cut with 850 irregular shapes to signifying the age of the city and portray the facet cutting of precious stones during manufacture. Over 800 rectangular copper-aluminum alloy panels form the external facade structure which is in turn supported by a complex substructure of galvanized steel. Approximately 65 tonnes of galvanized steel were used for this purpose. The new building merges design, art and architecture and has been described locally as a gold coat of armour turned inside out. It has however helped to raise the profile of the Association.






Hot Dip Galvanizing Magazine 2 2014

Spectacular steel roof


Vienna Central Railway Station (By Holger Glinde)


The new railway station has provided Vienna with a central hub in the trans-Europe rail network, which will be used by more than 1,000 trains and by 145,000 people every day. The station’s spectacular steel and glass lozenge roof, 200 metres long and 120 meters wide, has become a symbol of modern mobility and functionality, and distinguishes the building from everything around it. The roof structure, which is made up of 14 individual diamond shapes, arches over five platforms. Its height varies between six and fifteen metres, so that it seems to hover over the platforms. Each individual rhombus consists of rods and nodes. The entire roof (including the forecourt canopy) is made up of more than 57,000 sections, 286,000 sheets of metal, and almost 340,000 screw fittings which are concealed beneath the cladding. The creation of the gigantic structure was a demanding challenge for the contractors and the steel construction company Unger Steel, not only from the technological point of view, but also with regard to the logistics of the project.



Corrosion protection using hot dip galvanizing
The complexity of the roof structure meant that it would be virtually impossible to maintain so the design allowed for individual members to be galvanized and bolted together to form the complex rhombus for each subsection of the roof. It was therefore possible to avoid costly maintenance work which would entail closures along with health and safety issues.

The 14 diamond trusses of the station canopy each measure 76 metres, and are all supported by solid twin supports every 38 metres. In the centre of the lozenge, the structure opens up to provide a skylight in the form of a crystal shaped opening measuring 6 x 30 metres. Integrated glass elements make it translucent and helps to flood the building’s interior with daylight. At night, special lighting gives the roof a gorgeous 3D effect. For the architect, the central station is more than an important traffic hub: “It’s a turntable in a Vienna which is open to Europe. The lozenge roof makes an important contribution to this as, with its dynamic design, its rhythm and the way it seems to float in the air, it acts as a structural synonym for Vienna, the world-renowned city of music.”

Durable solar shading

British Embassy Offices (By Iqbal Johal)

The British Embassy offices in Harare, Zimbabwe, consist of a series of five, two storey buildings following the stipulations of the onerous brief; simplicity in design, ease of construction and a durable building. Set in its own secure compound, the flat landscape offers indigenous planting with shading afforded by the semi-mature trees.

Centrally placed within the site, the linked two-storey concrete ‘box’ buildings create a series of courtyard spaces providing a pleasant environment for officials and visitors alike. Although the buildings are structurally and environmentally flat roofed, a series of over-sailing mono pitch, freestanding roofs provide solar shading to the buildings on the north elevation due to Harare’s southern hemisphere locality.

Solar shading to the east and west elevations of all buildings is provided by avenues of semi-mature indigenous trees flanking the buildings and reflecting the vistas through the site. Additionally, external louvres are added at high level on the windowless, shorter east and west elevations. The trees not only shade the buildings but have the additional advantage of providing screening to the outer edges of the buildings and therefore giving privacy from the adjacent sites as and when they are built upon.

Externally, all the buildings are fair-faced concrete using shuttering constructed from galvanized sheet. Windows are aluminium framed and the mono pitch sheet steel roofs and louvres are all supported by a series of galvanized steel frames. Galvanized steel offered the best solution for a robust non-maintenance protective coating while also fulfilling crucial brief criteria of the best cost-effective solution. Material choice was an important element within the brief and maintenance would need to be avoided but there was also the need to select a palette that would reflect local materials.

Internally, finishes are simple. The shallow plan form allows for maximum daylight within the offices, all of which can be naturally ventilated using passive chimneys. Internal partitions are either glazed or white-painted stud and plasterboard with sustainable hardwood doors, frames and internal joinery.

External landscaping is predominantly grass with avenues of indigenous trees running in lines north to south, and on either side of the buildings which provide a soft and natural counterpoint to the angular geometry of the buildings. Shading from the trees on the building elevations is dappled rather than flat. The deep shadows under the angled roof planes help to create a sense of cool and calmness whilst a pond in the centre of the site adjacent to the reception block adds another layer of softening.

Open and inviting

Chatham Waterfront Bus Station (By Iqbal Johal)

The new Chatham Waterfront Bus Station (CWBS) is one of the key infrastructure projects within the £6billion Medway Regeneration plan at the centre of the surface transport network for the Medway towns and wider environs. The CWBS replaces a 1960s station located at first floor level within the adjacent Pentagon shopping centre that was locally known as ‘The Dark Side’ due to its largely internal nature with buses circulating around a circular track with passengers in the centre.

Architect: D5 Architects Photos: Simon Turner


The creation of the new station offers a considerably improved passenger experience in line with 21st Century expectations. It connects the shopping core of Chatham town centre with the waterfront area, increases public transport capacity and provides a fully accessible and safe environment for passengers, pedestrians and operators. The site was not without its challenges including being on the floodplain from the adjacent River Medway, being in close proximity to the proposed Chatham Docks World Heritage Site and set within the existing and active road network. But many of these challenges for the construction phase are now the major benefits the scheme offers providing improved pedestrian links within the established public realm and minimal change to the public transport network. Conceived as a public open space where you can catch a bus, the layout of the scheme went through a number of iterations and consultation before the ideal layout was established which integrates 20 operational bus stands into the road system, a new manned public information centre for the local transport network plus the refurbishment of the adjoining 19th Century White House to create back of house operational facilities. The design was conceived and developed as a public open space with platforms serving individual stands demarked through canopy roofs formed as organic, soft edged objects floating over the space. The site sits between town centre development, open parkland to the river’s edge and is surrounded by mature trees. The roof forms are articulated to sit within this landscape and provide continuity and contrast.

Already a local landmark, the soft forms of the canopies attract easy labelling and recognition making the station a strong identifier for the orientation of those unfamiliar with the town centre. Below the canopies the space is designed to flow with minimal barriers and for the benefit of the station user or casual pedestrian alike. A complex, three dimensional network of galvanized steel forms the framework for the canopy roof structures which is anchored to the ground through the ‘Y’ shaped galvanized and painted external supports. Seating areas are demarked by frameless glazed screens providing protection from the elements but with minimal formality and edges are blurred throughout to create a seamless journey through the station to all sides. Beneath the apparent simplicity of the built form, technology is employed to track all vehicle movements and input into the real time system with reporting to all platforms and stands on service punctuality and timing. This is designed for the future introduction of a fully dynamic system to increase capacity for the station. This system will track all vehicles and allocate stands to each service as it approaches the station directing passengers to the live stand thus increasing efficiency.



Hot Dip Galvanizing Magazine 1 2014


Light at the end of the tunnel

Wilhelm-Leuschner Station (By Holger Glinde)

Starkly geometrical, minimalistically reduced, the epitomy of rationalism and right angles. Anyone entering the Wilhelm- Leuschner-Platz Station of the new Leipzig City Tunnel will immediately recognise the typical style of Max Dudler, the architect who designed the station.

The Wilhelm-Leuschner-Platz Station is one of four along the 1.4 km length of the Leipzig City Tunnel. It extends north to south beneath the Martin-Luther-Ring to the centre of Wilhelm-Leuschner-Platz. The island platform at the station is 140 metres long and is located about 20 metres below the ground level. Access is provided by escalators, fixed stairs and a lift. The interior of the station is characterized by back-lit glass block elements, which help to create an impression of natural daylight.

Glass block facade
The station’s walls and ceiling contain a total of 130,000 glass blocks in 900 frames. The glass tiles are inserted into a filigree lattice steel made from exposed concrete. Due to the use of precast sections that had a maximum cover of only 20mm, hot dip galvanized reinforcing steel was used in order to avoid long-term corrosion damage, together with any possible unsightliness caused by visible spots of rust. Approximately 75 tonnes of hot dip galvanized reinforced steel was used in the facade facing. However, hot dip galvanized steel is not only suitable for thin-walled structures or prestigious exposed concrete structures, but can also be used for traffic structures subjected to road salt and buildings in a maritime atmosphere.


Hot dip galvanized facade infrastructure
The 900 modules of the glass block facade, each of which weigh 1.5 tonnes, are supported by a galvanized steel frame. Whilst the glass block modules were suspended from the ceiling by means of hot dip galvanized ‘spacers’, the facade’s wall elements are supported by a hot dip galvanized steel frame. In order to ensure easy access for maintenance of the 700 light sources for the backlit facade, four operating surfaces made from hot dip galvanized steel grids have been integrated between the tunnel wall and the frame structure.


Simplistic Beauty

The Astronomers Park (By Javier Sabadell)

In the eastern suburbs of Vitoria-Gasteiz, the political heartland of the Basque Country in Spain, it is still possible to enjoy a peaceful and relaxing walk in a park called ‘The Astronomers’. The name provides a clue to the history of the local area. Due to its location and terrain, the park had had a long link with astronomers using it to study the night sky. Current urban development precludes any possibility to perform astronomical observations, but the site still attracts local amateur astronomers.

Since 2000, the park has been developed to provide sporting facilities. A running track was laid along with a football pitch with a precast concrete structure to act as a shelter for supporters. With the increasing popularity of the local football teams, funding was sought for the enhancement of facilities at the park. A brief was drawn to include the construction of a new covered stand that would follow sustainable principles, be durable, vandal-proof, require minimal maintenance and be easy to extend. 

LMM Architects were chosen for their unusual yet simple proposal that met the brief. A 30-metre long trapezoidal, on side elevation, steel structure forms the main frame for the new stand. Galvanized steel inverted ‘L’ sections placed at five metre centres provide the skeleton of the structure that is clad with galvanized sheet. The lower level of the new stand uses precast concrete to provide changing rooms and a meeting room. Seating has been placed on top of the precast sections with a series of galvanized stairs that lead to the upper level of the stand. The simple design linked with effective engineering provides a light, durable, maintenance-free structure that can be used for many years to come by the locals to enjoy their football.



Hot Dip Galvanizing Magazine 2 2013


Regeneration is a prominent theme reflected through some of the projects featured in this issue. A spectacular leisure facility has been built on a former airport site in Bristol. On a smaller scale but just as important for the regeneration of Folkestone is the addition of a seafood restaurant on the seafront.

Linking old with new, a cycle and pedestrian bridge in Czech Republic provides a simple design solution that blends easily with its surroundings. On a slightly different vein is the weaving of a galvanized facade into a prominent structure in Stockholm.

We also feature an important article from European General Galvanizers Association (EGGA) and Swera KIMAB, a leading Institute within corrosion and materials research based in Stockholm. The article highlights the incorrect modern-day use of salt spray testing. Originally used for quality control of specific coatings or materials, the test has morphed into one that is used to generate misleading information on performance comparisons between different coatings.

Swera and EGGA do a commendable job in clarifying the reasons behind the misuse of this testing method.


Stockholm Exhibition Centre  (By Iqbal Johal, Galvanizers Association, UK)


When it is dark for more than half the year, a bit of indoor greenery can help brighten up the day. At least that was the idea behind the long ‘green’ walls inside Stockholm International Fairs which has recently been expanded and upgraded. Reflective surfaces and living walls help make the building feel larger, while specialized energy-efficient lighting brightens up the space. Designed by Stockholm-based Rosenbergs Architects, the large exhibition centre stands behind a rigorous sustainability policy aimed at reducing its impact.

The Stockholmsmässan International Fairs in Älvsjö is one of the world’s leading organisers of trade events, attracting 10,000 exhibitors and 1.5 million visitors annually. Rosenbergs architects has carried out a number of projects at the site since 1998. Their latest addition to the premises is a new multifunctional space intended for conferences and large exhibitions, the AE-Hall, which has now become one of the main venues of many fairs, such as the recent Stockholm Furniture Fair. The hall is connected to the existing complex by a gallery which has also been completely renovated, with new mirror-like ceilings and ‘green’ walls.

The new building makes innovative use of steel throughout the main structure and cladding system, which are closely integrated. Externally the AE-Hall is wrapped in a galvanized steel facade; a giant metallic shell which creates an embossing effect that is enhanced by the lighting fixtures integrated within the galvanized structure. The screen is made from 1,500 partly perforated galvanized steel panels.

From inside the AE-gallery, a pond with fountains is visible along most of its 100m length. The walls of the pool structure are clad in expanded metal screens with integrated sliding gates, revealing entrances to the subterranean car park below.

All of the visible roofs are covered in sedum plants and the centre features an energy-saving system with movement detectors that regulate lighting and temperature depending on how many people are in each venue. The exhibition centre also buys recycled office materials, uses eco-friendly cleaning agents, sources 60% of power from renewable energy sources and recycles 60% of its waste.

The large exhibition space is very versatile as it can be divided into smaller units, down to the size of a conference room if required. A more intimate ceiling height is achieved by height-adjustable lighting trusses, which are LED-illuminated. The sliding partitions are clad with aluminium panels, creating an intricate, lace-like pattern. The walls can be stacked in storage rooms along the hall, which helps to create a sound barrier to the train tracks to the north of the site.

The design for the facade screens was developed in close collaboration with Carl Hans Järnarbeten in Eskilstuna who built full-scale mock-ups where several crucial factors, such as light fixtures and the assembly system, were evaluated and tested. This resulted in a structure that could be optimized to serve multiple purposes in order to cut costs and avoid redundant structural systems. The perforated facade panels not only act as a cladding system, but also provide shade and support the lighting fixtures. The versatility of galvanized steel allowed the designers to use one single material for the whole facade, only varying the methods of processing: expanded, perforated or flat. The concept behind the project is described by Alessandro Ripellino: “We designed the facade of the building to be almost a woven fabric. It comprises of a network of galvanized steel sheets in varying forms. The idea was to create a very modern facade. This modernity is important for us in Northern Europe - where it is dark for six months of the year and the influence of light on the facade was a very important aspect of our design. We started this project ten years ago and galvanizing has been part of the process since the very beginning. With our latest phase however, we wanted to use it to create something that was a bit out of the ordinary and quite unique. The facade concept was inspired by the pattern within a wicker-type basket weave.”

Galvanized steel has enabled the designers to achieve the fascinating aesthetic that they wanted - a shimmering, reflective surface that offers light during the dark days of winter but also a variation when wet or dry and a totally different shimmer in the summer.

Diaphanous Frame

Hengrove Park Leisure Centre, Bristol (By Iqbal Johal, Galvanizers Association, UK)


The opening of Hengrove Park Leisure Centre was a date to celebrate for thousands of local people in Bristol. The state-of-the-art pool and leisure centre opened its doors, ready to showcase the region’s newest and most spectacular, multi-million pound leisure facility.



The £35m Hengrove Park Leisure Centre has been built on the site of a former airport. Its facilities include a 10-lane, 50m international-standard swimming pool, a 20m teaching pool with a moveable floor, sports hall, a dedicated spin studio, climbing wall, a 150-station fitness gym, a healthy living centre, and café and crèche. Bristol City Council along with contractors, Kier Construction, leisure provider, Parkwood Leisure, LA Architects and Ramboll formed the team that have brought the project to fruition. The architectural design features large areas of curtain walling that are almost transparent, giving a feeling of space and provide unobstructed views from the interior out on to the landscaped central plaza. The glazed facades also provide high levels of natural light and give the building a calm reflective feel at night.

The pool has a structural steel frame with the roof supported on a network of cellular beams spanning 37.5metres. In order to enhance light levels and create an interesting feature for swimmers, an elevated ‘bubble effect’ has been created over the central portion of the pool roof. The steelwork in this area is partially hidden by a suspended ceiling formed from a series of acoustic baffles that filter light and sound.


The Local Authority requirements called for the main structure to have a guaranteed life of 60 years with minimal maintenance. Traditional painting methods, utilising Chlorinated Rubber, were quickly discounted and the benefits of a factory applied, robust, homogenous finish led to hot dip galvanizing being selected. In addition to the main frame, galvanized components were used extensively throughout the project including structural steel frames around plant equipment and galvanized angle framework that supported the extensive suspended ceilings throughout the facility.

Structural Engineer for the project, Ramboll, researched the benefits of using galvanizing on a wider front. The sustainability benefits gained by using galvanizing over other methods of protection were quickly realised, in fact Hengrove is the first centre in the UK with a 50m swimming pool to achieve a BREEAM ‘excellent’ rating.

Engineered to last

Pedestrian and Cycle Bridge in Czech Republic (By Holger Glinde)

The Bohemian city of Hradec Králové, which lies between the Elbe and Adler rivers, provides a collage-like mixture of historical buildings from various periods of history. Medieval houses and counter reformation Baroque styles can be found, together with Postmodernist and contemporary structures.

Erecting a new structure against this background calls for a high degree of sensitivity, respect and discipline. These were some of the issues that architectural firm baum & baroš were faced with when they were commissioned to design a pedestrian and cycle bridge to link the historic town centre and its university campus. The bridge would fall within the protected environmental zone of Jirásek Park so all aspects of the design had to be carefully considered.

In addition to technical and functional issues, aspects of production, installation, economics, maintenance, aesthetics and long-term acceptance by the public also played a role in the multi-disciplinary planning for the bridge. This led to very close collaboration between the structural design team from Kosch–Führer–Jürges and the architects from baum & baroš. After careful consideration, it was decided to create a simple, modular steel structure fulfilling the following criteria:

• minimise cost through the selection of a simple, statically defined system
• reduce on-site operations to a minimum
• pre-fabrication of all constructional elements and selection of their dimensions with consideration being given to hot dip galvanizing of the steel
• minimise maintenance costs
• minimise repair costs by using bolted connections
• rapid installation with limited use of expensive lifting gear and ancillary structures
• sustainability to be a guiding principal throughout the project

The designers rejected an asymmetrical suspension type solution, which would be the usual choice in such cases, due to the size of the load-bearing mast that would be required and the visual impact caused within the Park.

The final design solution incorporates a truss with an understressed structure, derived from a Polonceau girder, with the upper beam forming the deck which is divided into two articulated sections. A tensioned cable in the form of a five-sided polygon creates the bottom chord of the truss. The transfer of loads is aided by the incorporation of three compressively stressed elements between the deck structure and the tensioned chord.

Rigidity was guaranteed in the horizontal plane by spacer bars and diagonal bracing. To enhance the lightweight construction and to reduce maintenance costs, a transparent and permeable structure made from 2.25 x 0.75m close-meshed galvanized grid plates was chosen for the surface of the deck. No vibration damping was required due to the inbuilt dynamic of the design.

When the project was completed, a simple, transparent and comprehensible structure was revealed. It has succeeded in not only creating a new link from the town centre to the university campus but also successfully integrating with its surroundings. The silver grey sheen of galvanizing will over time turn to a mottled grey that will naturally fade into the landscape of Jirásek Park.

Waterside Dining

Rocksalt Seafood Restaurant, Folkestone (By Iqbal Johal, Galvanizers Association)

Rocksalt Restaurant and Bar is a newly built destination restaurant in Folkestone Harbour and is the first restaurant venture for executive chef Mark Sargeant. The restaurant and bar forms a crucial milestone in the regeneration of Folkestone’s ‘Old Town’ and harbour, serving to reconnect visitors and the population of the coastal town with the working harbour and seafront. The restaurant is located on Folkestone’s harbour edge, adjacent to its working slipway where local fishermen unload their catch, delivering fresh fish to the restaurant daily.


Perched in the corner of the tidal harbour between a listed brick viaduct and cobbled street, the restaurant faces the former fish market. Folkestone boasts a small fishing fleet who off-load catches on to the slipway directly adjacent to the restaurant. The building sits on a new curved sea wall and borrows back land to form a wine cellar, and timber dolphin piles protect the building from stray boats. The building’s close proximity to the harbour waters meant that it was essential that the chosen materials were robust in order to withstand the marine environment.

On approach, the building presents itself from under a brick arch and then peels away from the cobbled street to reveal the harbour. Three curved walls, decreasing in height, are clad in shot-blasted black larch to echo the surrounding context. A slate plinth raises the building from the flood risk zone and elevates the views. Angled reveals on picture windows allow views into the kitchen, reflecting the working nature of the fish market, and offer views back to the street. The slate steps leading to the entrance merge into public bench seating at the top of the jetty facing out to sea.

At ground floor level, large glass sliding doors allow uninterrupted panoramic views of fishing boats at high tide and sandy shingle flats at low tide. Three large sliding doors expand the dining area to a cantilevered balcony with a glass balustrade and curved zinc soffit, ideal for alfresco dining. The interior of the restaurant takes strong influences from the immediate context. The interior colours emulate colours of the sea and sky – rising from dark, aquatic greens and dark tones of timber at ground floor; rising to a lighter palette of blues, greys and whites, contrasting with warmer shades of iroko on the first floor bar and terrace.

A steel frame construction was ideal for the architectural ambition of the building and allowed a tight programme to be achieved. Galvanized elements were a fundamental part of the steel frame in areas open and semi-exposed to the elements. On the ground floor balcony, iroko decking slats sit on large galvanized steel balcony support brackets bolted to the concrete slab, allowing the elegant structure to cantilever over the sea. Galvanized steel was also specified for semi-exposed areas of the external canopies on the ground and first floor terraces, helping to achieve slender cantilevered roof spans. The completed building sees its concept realised by re-engaging visitors and local residents alike with Folkestone’s rich coastal heritage, serving as a catalyst to revitalise the local area.

Beware - Salt Spray Testing

Misleading Accelerated Corrosion Tests (By Lena Sjogren of Swerea KIMAB and Murray Cook of EGGA)

If you are a user of protective coatings in the construction, manufacturing or engineering industry, there is one aspect of corrosion science that requires your careful understanding – that is the role and limitations of accelerated corrosion testing. For decades, the so-called ‘salt spray test’ has generated misleading information about coating performance and its results still feature prominently in the marketing materials of products that, artificially, yield more favourable outcomes than in the real world.

So what is wrong with the ‘salt spray test’?

Firstly, the test does have some value for quality control of a specific material or coating. This is what the test was originally designed for and it is used successfully by some industries for this purpose. Although, it is now largely abandoned even by the automotive industry. The serious misuse of the ‘salt spray test’ is its use to compare, or rank, different materials or coatings that have differing characteristics. It is especially misleading to use the test to compare paints with metallic coatings. It is equally misleading to compare different metallic coatings. For example, comparisons between zinc and zinc alloy coatings (such as those containing small additions of magnesium and aluminium) can produce comparative results that are vastly different to real in-field performance.

Unfortunately, material comparisons are still made using the test despite the international standard for the test (ISO 9227) clearly stating that ‘There is seldom a direct relation between resistance to the action of salt spray and resistance to corrosion in other media, because several factors influencing the progress of corrosion, such as the formation of protective films, vary greatly with the conditions encountered. Therefore, the test results should not be regarded as a direct guide to the corrosion resistance of the tested metallic materials in all environments where these materials might be used. Also, the performance of different materials during the test should not be taken as a direct guide to the corrosion resistance of these materials in service.’ [1] Instead, ISO 9227 recommends that salt spray tests are suitable only as quality control tests. A large number of peer-reviewed papers havealso given clear warnings about the use of the salt spray test. Here are some extracts from just a few:

‘In fact, it has been recognised for many years that when ranking the performance levels of organic coating systems, there is little, if any, correlation between results from standard salt spray tests and practical experience’. [2]

‘Salt spray is the most widely used accelerated test. It was developed more than 50 years ago for testing metallic coatings in marine environments. Although it has been demonstrated that this test does not provide a good indication of outdoor service performance of coatings (even in a salt atmosphere), its use has become entrenched in the coatings industry’. [3]

‘The well-known ASTM B-117 salt spray test provides a comparison of cold-rolled and galvanized steel within several hundred hours. Unfortunately, the salt spray test is unable to predict the well-known superior corrosion resistance of galvanized relative to uncoated rolled steel sheet.’ [4]

‘Salt spray provides rapid degradation but has shown poor correlation with outdoor exposures; it often produces degradation by mechanisms different from those seen outdoors and has relatively poor precision’. [3]

Unfortunately, despite these warnings, salt spray testing is still used in communications to introduce new coatings and materials to the market.

Why does salt spray testing give misleading results?

To understand why the ‘salt spray test’ fails to reliably predict real corrosion performance, it is important to look at the test procedure. Samples under test are inserted into a temperature-controlled chamber where a salt-containing solution is sprayed, at 35°C, as a very fine fog mist over the samples. As the spray is continuous, the samples are constantly wet, and therefore, constantly subject to corrosion. Performance is rated by recording the number hours to reach defined levels of surface rusting. Test duration ranges from 24 hours to 1000 hours or more. There are some obvious reasons why the salt spray test does not correlate with real world exposure conditions, in particular: The surface of the test coupons is constantly wet, with no cyclic drying, which does not happen in reality. This prevents metals, such as zinc, from forming a passive film as it would in the field. The chloride content is very high (normally 5% NaCl) resulting in highly accelerated conditions with different acceleration factors for different metals and metal constituents. These are unusual and severe conditions that probably never occur during normal outdoor exposure.

Salt spray testing cannot successfully compare corrosion resistance of materials

It is well accepted that the good performance of metallic zinc coatings in real outdoor conditions relies on drying between periods of wetness. The development of a passive and relatively stable oxide and/or carbonate film during the drying cycle contributes to the excellent performance of galvanized coatings. The continual wetness during the salt spray test does not allow this passive oxide/carbonate layer to develop. The test therefore artificially reduces the performance of zinc coatings.

When painted material is evaluated using the salt spray test, there is no exposure to ultraviolet light, a common cause of breakdown of paints. This is a serious omission, since the main failure mechanism that causes painted steel to deteriorate is not included as a condition in the salt spray test. The salt spray test can give similarly misleading results when comparing different variants of zinc coatings. For example, small additions of magnesium or aluminium to a zinc coating will produce salt spray test results that differ significantly from real exposure conditions. Magnesium ions, whether from the environment (sea salt) or in a zinc alloy, promote the formation of protective corrosion products in the presence of sodium chloride, thus reducing corrosion rates. This explains why zinc-magnesium-aluminium coatings show artificially better performance, as compared to zinc, in accelerated tests involving high time of wetness and high chloride load. This effect also occurs in field exposure tests in some, e.g. marine atmospheres but with a substantially lower level of improvement than is indicated by salt spray test results.


The use of salt spray test results to guide selection of protective coatings for steel remains a serious problem in the engineering community. Despite the well understood limitations of the test in the ‘corrosion world’, it is still used to promote the use of coatings whose properties happen to produce apparently favourable results. It is hoped that this article has given some insight into the scientific background to the limitations of this type of accelerated testing. Regardless of the attractiveness of quick and short-term information, there is no substitute for corrosion data generated from long-term exposure testing and case history information from real structures or components in service.

[1] ISO 9227 ‘Corrosion tests in artificial atmospheres – salt spray tests’.
[2] Skerry, J S, Alavi, A and Lindgren, K I. ‘Environmental and Electrochemical Test Methods for the Evaluation of Protective Organic Coatings’, J of Coatings Technology, vol 60, No 765, p97.1988.
[3] Appleman, B. ‘Cyclic Accelerated Testing: The Prospects for Improved Coating Performance Evaluation’, J Protective Coatings & Linings, p71-79. Nov 1989.
[4] Townsend, H E. ‘Development of an Improved Laboratory Corrosion Test by the Automotive and Steel Industries’, Proceedings of the 4th Annual ESD Advanced Coating Conference, Dearborn, 4 USA, 1994