Encaustic Tiles at the Palace of Westminster

Adam Watrobski

 

The geometric forms - stars and octagons - of the lobby pavement  
The Central Lobby pavement from above (All photos: Adam Watrobski/UK Parliament)  

The Palace of Westminster was destroyed by fire in October 1834 and a competition was held to build a new houses of parliament on the same site. Charles Barry (1795-1860) was selected as the architect of the vast undertaking and he chose the passionate Gothic Revivalist, Augustus Welby Pugin (1812-1852) to design the decorative elements, including the encaustic floor tiles.

In February 1843 Barry suggested that ‘the floors of the several Halls, Galleries and Corridors, should be formed of encaustic tiles, bearing heraldic decorations and other enrichments in colours, laid in margins and compartments in combination with polished British marbles’.

The term ‘encaustic’ is a 19th-century invention. It was originally taken from a Greek word meaning ‘burnt in’ but, in the context of tiles, a better description would be ‘inlaid’. The encaustic process was introduced into this country from France at the beginning of the 13th century and the tiles were much used in abbeys and royal palaces.

The encaustic tile process was revived in the 1830s prompted by the work of Samuel Wright from Staffordshire, who registered a patent in 1830 which utilised a plaster mould with the pattern carved into it set in a metal frame and a screw press to force the clay into the mould. The resulting indented pattern was then filled with clay slip and planed level with a cutting tool. Wright was unsuccessful financially and soon sold a share in his patent to Chamberlain & Co of Worcester (Maw & Co after 1849) and to Herbert Minton (1793-1858) of Thomas Minton & Sons, the pottery firm started by his father in 1793. Herbert Minton had both the resources and tenacity to develop the process into a commercial success.

With the help of Pugin, Minton developed the production of tiles with up to six colours by 1844.[1] Although the coloured clay was a relatively thin layer, the tile had an overall thickness of 25mm (1 inch). This was achieved by introducing a deep layer containing ‘grog’ and a low quality, cheap red clay, sandwiched between two layers of higher quality buff clay.[2]

At the Palace of Westminster, the fabric of the tiles is integrated with the architecture of the important sequence of six main halls and a further dozen or so linking corridors and staircases forming the entrance and communication routes through the ground and principal floors. Each floor displays a different pattern consisting of panels or compartments of encaustic tiles in large, symmetrical layouts with wide borders of stone flags made from Valentia slate in the House of Commons floors or, in the Lords areas, borders using Hopton Wood stone.[3]

Tile patterns include the lion of England, the floral emblems of constituent parts of the United Kingdom and mottos in Latin and English in beautiful gothic script. The colours range from yellow ochre and burnt sienna to a vivid cobalt blue with details of pearl white and plain tiles of caput mortuum.[4] It is estimated that Minton produced around 75,000 tiles to complete the complex and technically exacting contract between 1847 and the date of the official opening of the whole palace by Queen Victoria in February 1852.[5]

  Historic tile press and tools A craftsman hand carves patterns into a plaster mould with a pointed metal tool
  An original hand-operated tile screw press, Gladstone Pottery Museum, Longton, Stoke-on-Trent Carving the pattern to form a plaster tile mould
  Panel of worn tiles: several have little or no surviving pattern Slip clay is hand poured into a series of tile moulds
  Worn tiles, St Stephen’s Hall Pouring coloured slip clay into a mould

Heavy wear has led to the loss of part or all of the coloured areas to many tiles and an undulating floor profile. Some tiles have suffered mechanical damage, revealing the inner core material and many have become detached from their backgrounds. Visual inspection shows that the replacement of tiles has been extensive.

Individual tiles are known to have been replaced in the 19th century, while in the 20th century some areas were completely re-laid with new tiles and stone flags because of bomb damage during the second world war or because they had worn away. 

Minton tiles ceased production in the 1960s and new tiles for repairs after this date came from various sources and were often not a good match for the originals. Wear and tear had worn many of these replacement tiles beyond temporary repair and in many areas the damaged tiles had become a trip hazard.

The Palace of Westminster is a working building with about one million people entering it every year and it is not possible or desirable to re-route the members, staff and public away from the tile floors. In considering new approaches to the repair and conservation of the floors and assessing the results of a small amount of repair work done in the late 1970s and early 1980s, as well as trial areas laid in 1998 and 2004, the following points were evident:

  • The differences in artwork quality in the reproduction of original designs tended to disrupt the continuity of pattern across the floor.
  • Replacement tiles used in the later 20th century were 13mm thick – around half the thickness of the Minton originals – and were designed to be laid on a hard mortar bedding as a floor finish. The original construction of 25mm (1 inch) tiles laid in soft mortar had a monolithic quality able nevertheless to accommodate movement without cracking.
  • Temporary repairs had been carried out using coloured epoxy resins, introducing both visual disharmony and guaranteed failure.

At an early stage, different strategies for the conservation and repair of the floors were identified and assessed as follows:

  • Do nothing, except repair for safety reasons. This would reduce the risks of accidents while retaining the historic fabric but it would not conserve the original fabric and would not address the significant aesthetic issues of the worn tiles.
  • Leave the tiles as found and cover them with duck-boarding or carpet. This might prevent future wear but would also drastically undermine the architectural integrity of the pavements as originally intended and, at the same time, introduce new and incongruous elements to some of the most important areas in the palace.
  • Completely remove existing tiles and re-lay using new tiles not matching the originals. The gains in safety and durability offered by this line of action would be substantially outweighed by the loss of historic fabric.
  • Completely remove existing tiles and re-lay using new specially made replica encaustic tiles to match originals in colour, shape and pattern. This would both retain the original design of the floors and provide a new and durable level floor free of defects and unevenness. The disadvantage is that it would result in the loss of much historic fabric that might otherwise be retained and repaired.
  • Locally replace tiles and stone flags according to a critical methodology based on the selective assessment of the condition of both the existing tiles and the associated stonework. This option would retain the historical integrity of the building, prolong the life of the original tiles, guarantee the durability of these heavily trafficked pavements and give an appearance of consistency.

The last option was considered the most appropriate.

Heavy footfall in the building made frequent repairs to the tiles necessary. This precluded repairing the tiles in situ using, for example, plastic repair methods. Rather, damaged tiles would be replaced with new ones in close facsimile to the originals in terms of visual appearance and physical qualities. On balance, it was considered that the extensive replacement of tiles that this would entail would be acceptable as an alteration to the historic fabric. This conclusion – that the significance of the design of the pavements is more important than that of their fabric – was reached by reasoning that:

  • The long history of repairs to the encaustic tiled floors makes it impossible to identify with certainty tiles that are original against those that have been replaced.
  • The loss of decorative pattern over large areas of the pavements due to their excessively worn condition detracts from the overall presentation of the highly significant interiors of which the encaustic tiles form a major part.
Two triangular sections of tiling showing the brighter colour and sharper detail of the new tiles With a plywood screen behind him, a craftsman beds a new tile in mortar at the Palace of Westminster
Comparison between new and old tiles, Central Lobby Laying new tiles

Before comprehensive proposals for repairing the encaustic tiled floors could be brought forwards, a combination of site surveys and investigation and a trial repair was necessary. A full photogrammetric survey was made of all floors before work began and a photographic record was made of each stage of the processes which followed.

Opening up was undertaken in discrete areas of the floors in St Stephen’s Hall and the Members’ Entrance in order to clarify these issues. This confirmed that the tiles were originally bedded and pointed in a moderately hard mortar in a single operation. The tiles, which are one inch thick, have slightly canted edges to facilitate laying in this manner. In all cases, a very hard grout appeared to have been applied subsequently. Bases included York stone flags and weak cement screed over rubble infill. Samples were taken of all mortar and screed materials for laboratory analysis and tests confirmed that the original bedding and pointing materials contained an early Portland cement.

Product development to produce a tile of one inch thickness started in 2008 and was undertaken in conjunction with Chris Cox of Craven Dunnill Jackfield at Ironbridge, Shropshire. Practical tests included undertaking development work in order to provide control samples of new tiles that accurately matched the originals in terms of decorative designs and colours. Materials testing to confirm the slip resistance, surface porosity and wearing characteristics of the new tiles was also carried out. It is important that in time, the new tiles should wear in a similar manner to the historic ones.

Modern manufacturing techniques are based on those of Samuel Wright and Herbert Minton but with some obvious differences. Mechanisation of the clay milling process significantly reduces the health risks of manufacture. Modern kilns, fired by gas or electricity rather than coal or wood, make greater control of the firing process possible, allowing very precise matching of original colours, cutting waste and reducing the carbon footprint of manufacture. Better control of distortion allows the tile body to be made of one piece of clay, rather than in the three layers used by Minton. Craven Dunnill Jackfield was able to accurately match the artwork of the original tile designs and to make clays which, on firing, gave a precise match to the colour of the original materials used.

Low-angle shot of an expanse of repaired tiling with a small area in the foreground of the original badly worn tiles  
Repaired area, St Stephen’s Hall (note small unrepaired section, bottom right)  

New slate was sourced from the Valentia mine on the Iveragh Peninsula in County Kerry, Ireland, where the material used in the floors was originally extracted. Colour variations were noted between the new slate and the slate in the existing floors. This is possibly due to natural variation, although it is also probable that the colour of the original flags had changed due to the historic use of oil or wax in cleaning.

The Hopton Wood quarry near Wirksworth, Derbyshire ceased production of building stone in 2009 but a small amount of stone was still available from reserves previously extracted and this proved sufficient for our needs.

Mortar analysis formed the basis for the design of an appropriate modern mortar for the repairs. The properties of early cements varied considerably but they were very much weaker than modern Portland cement, being closer to an eminently hydraulic lime in strength. A hydraulic lime binder was therefore used in the repair work.

An area in St Stephen’s Hall of approximately 47 square metres was identified for trial repairs. The repair methodology adopted for this trial was based on the following principles:

  • Tiles and stone that were in good condition, including tiles slightly chipped around the edges or with minor cracks not detracting from their overall appearance, would be retained in situ wherever possible.
  • Tiles that were badly damaged or that had completely or nearly lost their pattern (including tiles previously replaced with inappropriate substitutes or poorly repaired) would be replaced. Some panels of tiles would thus be replaced in their entirety.
  • Tiles that were partially worn with an estimated remaining life span of 15 or 20 years and which still displayed a complete pattern would be removed from areas of the floor which are otherwise badly worn and thus need complete replacement. These salvaged tiles would be used for the individual replacement of tiles of the same pattern in areas of lesser wear.
  • Worn or broken flags of Valentia slate and previous inappropriate replacements of historic Valentia slate would be renewed.
  • New tiles and salvaged tiles being reused would be bedded in a layer of mortar of a mix designed to be sympathetic to the historic fabric. Tiles would be bedded and pointed in a single operation.

Working closely with DBR London to lift old pavements and re-lay them, Strategic Estates has carried out the programme without unnecessary disruption to the working of parliament or the reception of its visitors. A controlled environment working inside tents with vacuum air filters is employed to protect people, the built fabric and works of art within the palace.

The trial was very successful. The methodology of complete lifting in some areas and piecing in repairs to others was clearly demonstrated. More recently, the repair and conservation of several more floors has been initiated, including those of the Members’ Entrance, Lower Waiting Hall, Central Lobby and the Royal Gallery.

In January 1852, Pugin wrote a letter to Herbert Minton in which he said: ‘I declare your St Stephen’s tiles are the finest done in the tile way, vastly superior to any ancient work; in fact, they are the best tiles in the world and I think my patterns and your workmanship go ahead of anything’. The careful and respectful approach to revitalising the Palace of Westminster’s tiled pavements is one that strongly echoes that dedication to design and workmanship.

 

~~~

Further Information

Craven Dunnill Jackfield Limited

L Durbin, Architectural Tiles, Conservation and Restoration, 2nd ed, Routledge, London, 2014

L Durbin, ‘Conservation and Restoration of Pugin Tiles at the House of Commons’, Context, 54, 1997

Gladstone Pottery Museum

The Jackfield Tile Museum

H van Lemmen, Tiles: 1000 years of Architectural Decoration, Abrams, New York, 1993

The Minton Archive www.themintonarchive.org.uk

The Potteries Tile Trail

Tiles and Architectural Ceramics Society

For more information on the encaustic tile floors at the Palace of Westminster, please email architectureandheritage@parliament.uk.

Notes

1 Minton’s first encaustic pavement was laid in 1842 at the Temple Church, City of London. An early use of Minton’s tiles by Pugin was for St Chad’s Roman Catholic Cathedral, Birmingham in the early 1840s.

2 Grog also helps to prevent shrinkage. The tiles are stamped on the back: ‘Minton & Co Patent, Stoke upon Trent’.

3 Hopton Wood is a pale limestone which has been used as an indoor paving stone since the 18th century and polishes naturally to an eggshell finish.

4 Caput mortuum (literally ‘dead head’) is a dark purple-brown.

5 Minton also provided glazed, dust-pressed, block-printed (Collins and Reynolds original patent) tiles as an easily washable surface for the dado of the Strangers’ Smoking Room, now the Terrace Cafeteria servery. These tiles were repaired in 1994-6 by Jackfield Conservation Studio and the Decorative Tile Works.

 

 

The Building Conservation Directory, 2017

Author

ADAM WATROBSKI BA(Hons), DipArch, DipConsAA, RIBA is the principal architect and head of architecture and heritage at the Houses of Parliament.

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