More than a sign: London Underground’s iconic tiles
Kathryn Allen takes a look at the iconic ceramic tiles and signage used on the London Underground.
In July 2011, on the advice of English Heritage, 16 additional London Underground stations were given Grade II listed status, taking the total up to 71, in order to preserve the stations’ architectural features.
The London Underground dates back to 1863, when steam locomotives pulled wooden carriages along the Metropolitan Railway, which stretched from Paddington to Farringdon, and today comprises 11 lines serving 270 stations. The architecture of these stations varies considerably due to age difference and the various architects hired to design them. However, a fairly consistent feature throughout these stations is the presence of ceramic tiles.
Railway engineer John Fowler designed many of the stations serving the early lines – Metropolitan and District. These stations, including Paddington, Baker Street and Great Portland Street, were designed to be airy to allow for the smoke from the locomotives to disperse.
Expansion of the tube lines in the late 19th and early 20th centuries and the development of the electric locomotive, which allowed tube lines to be built deeper underground, saw a change in station design. Architect Leslie Green specified oxblood-coloured ceramic tiles and arches on the station exteriors, often using decorative green and white tiles on the interiors. Along with Russell Square, Kentish Town and the now disused Down Street, the ticket hall of Holloway Road station illustrates this design, with the bottom half of the walls clad in green tiles and topped with decorative and white tiles. The station names and directions were often indicated using tiles.
Covent Garden, one of the stations given Grade II listed status in 2011, is also typical of Green’s style. Historic England cites the station’s original tiled signage and oxblood-coloured façades as the reasons behind its protected status. Tiling in the ticket hall has since been refurbished, with the original 1906 tiles replaced by replicas. The platform and lower passage tiles were replicated in 2009, while original tiling has been preserved in the spiral stairway.
In the early 1900s, stations designed by Charles Clark were either reflective of Metroland – a term coined by the Metropolitan Railway describing the developing suburbs of northwest London – and its suburban, idyllic image or, for those stations nearer to the city centre, marble white exteriors. Charles Holden was also designing stations in the 1920s, including those on the extension of the Northern line and on the Piccadilly line, where he redesigned stations such as Oakwood in a modernist style.
According to Transport for London (TfL), in the post-war period, station design was limited due to poor economic conditions. However, this didn’t last, with the building of the Victoria line in the 1960s leading to further platform design at the stations it linked. Grey tiled walls and decorative tiled panels, relating to the station’s name or the history of the area, above platform seating can be found at some of these stations. Artist Edward Bawden created the tiled panel of Queen Victoria’s silhouetted head at Victoria underground station.
Art on the underground became a focus in the late 20th century. Eduardo Paolozzi’s mosaics at Tottenham Court Road, completed in 1986, have recently been restored following the station’s expansion. Around 95% of the original mosaics have been retained, with original tiles being reused where possible and new tiles colour-matched to the old, according to TfL.
With the extension of the Jubilee line in the 1990s, designers under the guidance of Roland Paoletti focused on creating large areas of well-lit space employing heavy-duty materials – Canary Wharf is an example.
A corporate image
The use of tiles throughout the London Underground aims to create a consistent corporate image. Veronica Fiorato, Historic England’s Listing Team Leader in the South, told Materials World, ‘The London Underground is to be greatly admired for its commitment to quality and consistency of design, which has helped in the creation of a globally recognised brand. The listed underground stations are among the most architecturally impressive and best preserved of London’s historic underground stations, worthy of recognition and protection for their contribution to London’s architectural story.’
Contributing to this image is the roundel, first used in 1908, but not officially named as London Transport’s corporate symbol until 1972, and the Johnston Sans typeface, commissioned in 1913 by Publicity Manager Frank Pick, who went on to become Managing Director of London Underground. The signature look of the Tube has become a tourist attraction, with the iconic roundel often imitated on tourist merchandise.
Despite this desired corporate image, individual station designs varied, with unique tiling patterns helping commuters recognise the stations – crucial in the Tube’s early days when not all commuters were literate. This set a trend, with tiles used to creatively indicate stations – a red tile maze at Warren Street, cartoon silhouettes of Sherlock Holmes at Baker Street, a pile of bricks at Brixton and the crown jewels at King’s Cross.
While adding to London Underground’s corporate image, the roundel’s primary purpose is to indicate the station’s name and the traveller’s location. It must stand out against surrounding advertising and be long-lasting.
AJ Wells & Sons Limited, UK, a family-run manufacturer of vitreous enamelled signs and cladding products, has been making signs for the London Underground since 1990.
After a fire at King’s Cross underground station in 1987, it was decided that materials used on the underground needed to be fire-resistant, including the signage, so vitreous enamel was used.
A highly durable material, vitreous enamel is a thin layer of powdered glass fused to a metal base, usually steel or cast iron. Explaining the process of making a vitreous enamel sign, Cedric Wells, of AJ Wells & Sons, told Materials World, ‘Firstly, the sign is created in a low carbon steel, which is laser cut to size and shape, folded and degreased to remove any impurities from the surface. The raw steel sign is then sprayed with an enamel ground-coat consisting of powdered glass, quartz, clay and oxides suspended in water. The sign is placed in a dryer to allow the water to evaporate and then fired in a furnace at around 800°C. At this point, the glass base fuses to the steel creating an extremely durable surface finish. This process is repeated with a topcoat – usually white. Once cooled, the sign is screen printed with graphics using enamel inks – a powdered glass base suspended in pine oil – and then fired for a third time. Depending on what type of sign it is, the sign is then backed or framed.’
This process makes the enamel robust and easy to clean, meaning it can be used for a variety of purposes – as well as street signs – such as coating storage tanks, kitchen surfaces and steel or cast iron baths.
Saqlain Ali, Technical and Process Development Director at Permastore Limited, adds another benefit of using vitreous enamel. ‘There's a vast array of different properties that a vitreous enamel finish delivers to a product – ultimately the coating enhances the product lifecycle. Vitreous enamel is not the lowest cost coating material, primarily because it requires high temperatures to achieve the fusion of the enamel and the substrate. Therefore, the costs are influenced by the high-energy requirements and the price of the materials used.’
However, he adds ‘due to the excellent product lifecycle, the comparative cost of vitreous enamel coatings is hugely beneficial over competing materials. Vitreous enamel coatings have a range of baseline properties that can be enhanced using appropriate formulations and processing to achieve specific requirements of the final product that is being produced.’
Ali cites the material’s anti-graffiti properties as crucial to its use in signage. Vitreous enamel is able to withstand a range of cleaning solvents, both acids and alkalis, while other coatings may only be resistant to one or the other. The material’s durability, temperature-resistance and colour stability are additional benefits when used for signage.
Darrel Nichols, Director of Trico Vitreous Enamellers, UK, lists a long life expectancy, hygiene, durability, low-maintenance and resistance to corrosion as advantages of using vitreous enamel. However, he warns, ‘a good installation of the signage panels is important, the edges of the signage panels should be concealed so they are unexposed to the elements.’
TfL's corporate image relies on the tiles remaining in good condition, giving an impression of orderliness. The tiles have to be maintained – damage is not only caused by day-to-day wear and tear but also during station expansion. In 2012, Blackfriars station reopened following three years of refurbishment work. Johnson Tiles and Craven Dunnill Jackfield supplied the new bespoke glazed ceramic tiles.
Adrian Blundell, Production Director at the latter company, told Materials World, ‘Over the last 15 years, us and Johnson Tiles have worked in partnership on the extensive new build and restoration programme for the London Underground. This is an ongoing programme and is continuing today at Liverpool Street, Victoria, Vauxhall and Moorgate. We manage the projects and manufacture the specialist glazed tiles including embossed 3D tiles, while Johnson Tiles produce the volume, field tiles.’ Blundell continued, ‘For the renovation of Blackfriars station, two styles were specified, which Johnson Tiles produced – a large format, speckled-glazed tile and a satin blue, square tile. These glazes were specifically developed to emulate smaller speckled glazed tiles originally supplied to London Underground stations in the 1920–30s by Carter & Co, including Aldgate East, Wanstead and Bethnal Green.’ A floating fleck, produced for projects on the London Underground, features in these tiles. Blundell explains that the tiles for Blackfriars are pressed, glazed, dried, fired and packed using a fast-fire single layer roller kiln.
As well as expansion and wear and tear, vibrations and damp result in stations needing refurbishments, as Kate Fulcher discusses in Conserving Heritage Tiles on the London Underground: Challenges and Approaches. Tiles can be refurbished through patch repair, over-tiling or replacement. Patch repair involves repairing damaged tiles or replacing with replicas, rather than stripping the tiles off the entire area and replacing them all – the replacement method. Original tiles can be repaired by filling in chips with a mixture including pigmented polyester or epoxy resin. However, patch repair can result in an inconsistent finish, with original tiles next to repaired and new tiles.
This inconsistency is not an issue when all tiles are stripped and replaced. However, the replacement method is not always well received when traditional designs are changed. In 2015, the Chelsea Society and Greg Hands, Conservative MP for Chelsea and Fulham, opposed the replacement of Sloane Square’s green tiles with white ones.
Over-tiling, where replica tiles are stuck on top of the original tiles, can only be done when the original tiles are in good condition. This method is cheaper than the other two, as the colour-match between old and new tiles does not need to be exact and no tiles need to be removed.
The historic value placed on the London Underground’s tiles is evident not only in the listed status of many stations, but also in how iconic the tiles and corporate image have become.