Medieval Mastery

Looking back at past issues of both Tile UK and Tile & Stone Journal to prepare this blog has been a joyous trip down memory lane. Over the years I have met some truly inspirational tile makers and designers; individuals with a real love of the material and its limitless potential. Few have had such an intimate relationship with clay as Diana Hall, whom I interviewed in her Dorset home in 2001. Her total immersion in her work has resulted in many painstaking restoration projects and some wonderfully tactile inlaid tiles that have a quality one can only describe as spiritual.

Diana Hall
Diana Hall at work in her studio in 2001

Diana Hall first started working with clay in 1979, when she established a hand-printed ceramic tile business in Sussex with Peggy Angus using designs from medieval tapestries. She was taught the fundamentals by Peggy Angus and a local potter, Chris Stevens, at the weekends; the weeks being taken up by her four children.

A series of small local commissions encouraged her to expand and hone her skills, and, by 1985, she had successfully diversified into making replica Medieval and Victorian inlaid tiles using traditional techniques.

Another early source of inspiration for Diana Hall was Prof. Bobby Baker who had made replica tiles for Winchester Cathedral and Wells Cathedral in the 1970s. Indeed, Peggy Angus herself studied under Prof. Barker at the Royal College of Art. Although Diana Hall has learnt a lot from her mentors, and read widely in an effort to perfect her techniques, the development of faithful reproductions of medieval tiles remains largely a process of trial and error, with the end results hugely influenced by the choice of clay, and the reaction of particular glazes to that clay. Some clays, for instance, fire much darker or make gloss glazes fire matt. Diana Hall has built up a library of success, and failures, in her workshop which now acts as a useful reference source.

Her commissions are principally ecclesiastical or from private individuals. They have included the manufacture of replica medieval inlaid tiles for the Retrochoir Pavement at Winchester Cathedral; Prior Crauden’s Chapel at Ely Cathedral; the Court House at Martock; conservation and replacement of tiles at St Nicholas church, Arundel; restoration of medieval inlaid figurative panels at Chertsey Abbey; and a new floor for the Herbalist Room at Wenlock Priory.

Replica Victorian encaustic tiles have been produced for the Law Courts at the Aldwych and, more recently, Diana Hall has re-made some 19th century architectural terracotta pieces for the roof of St Stephens and All Martyrs at Leverbridge, Bolton.

While restoration projects provide the bulk of her work, Diana Hall has also won some interesting new commissions, from a hall for a vintner, to a walled garden in Hampshire; the latter designed using sacred geometry and incorporating the signs of the Zodiac.

One project of which Diana Hall is particularly proud is a replica fourteenth century Penn tile, commissioned by Susan Andrews, Yelverton, Devon, depicting the three hares design from Long Crendon Church, Buckinghamshire.

Having evaluated other working methods, Diana Hall has now perfected the manufacture of inlaid tiles. Inlaid tiles are similar to encaustic tiles; with slip inlaid into a hand-pressed clay body. The clay tiles generally feature a simple pattern, such as an heraldic motif, picked out in a clay inlay of a contrasting colour; usually in white on a red ground. The tiles are then glazed and fired; originally in wood-burning kilns. During the firing process some vitrification occurs in the glaze, resulting in a hard finish that gives the tiles some wear resistance.

The first step in any restoration project is research. If the original floor is badly worn, this can help reveal the original patterns and designs. Research can often shed light on the clays used in the original tiles, which is a vital piece of information when it comes to producing accurate reproductions. Examination under a microscope will often reveal more about the body fabric, colour and texture. Experiments are then conducted to get the right body and a compatible slip inlay. Glaze trials are then undertaken. Glaze preparation is a real black art. At Winchester, for instance, Diana Hall found that galena (a mineral form of lead sulphite) suspended in beer lees produced the required chestnut glow.

As with any hand-making process, producing inlaid tiles is very time consuming. Diana Hall produces, on average, just 20 tiles per day. They are formed in a mould, usually hardwood. The choice of wood is important. Some, like beech and oak, are very hard, but prone to cracking. Others are easy to carve, but cannot maintain detail over a long production run. For really detailed work, Diana Hall prefers holly, but even that can split, which is not surprising when you see the forces required to drive the clay into the mould and eliminate any air pockets. Some synthetic materials give excellent results, but the degree of detailing is too sharp for restoration projects. Lead moulds have also proved effective for certain tile designs.

Diana Hall’s work proves how the choice of clay influences the finished tile. As a purist she prefers to work with hand-dug clay, but this is time consuming. Once the required body clay has been found it has to be purged of stones and larger organic matter. It must then be soaked and pugged; the end result being solid blocks of clay that can be cut, weighed and then forced into the slightly over-sized moulds to make the body. If there is no reason to use hand-dug clay, Diana Hall will use bought clay but the end-results, such as the reactivity of the glaze, can be vastly different.

Once the body clay is pressed into the mould, the tiles are then stamped to produce the required pattern in relief, leaving a clear impression on the surface of the clay body. Keyholes are cut in the back of the tile to aid the drying process, and help the finished tile to key into the mortar when laid. The impressed pattern is then filled with a slip, usually white, and left to dry. When the tile is leather hard, the excess slip is cut away to reveal the definition of the pattern. The tile is the shaped and trimmed, before the glaze is brushed on. As wood-fired kilns are no longer economic or practical, the tiles are now fired in a gas-fired kiln at around 1,080oC. Fortunately gas-fired kilns provide sufficient variation in the degree of oxidation and reduction to produce the desired range of colour tone in the glaze. Firing is a two day process: 24 hours to fire and 24 hours to cool. Shrinkage is a considerable challenge to overcome, with around 8% normal. This means that the clay body and the slip have to be highly compatible if losses are not to occur in the kiln.

With her depth of practical experience, plus the theoretical and analytical skills picked up as a mature student on the new heritage conservation course at Bournemouth University, Diana Hall is now in demand as a consultant, preparing condition reports and advising the church and heritage bodies on conservation strategies for old floors, including Medieval tiled pavements.

However, tile manufacture remains Diana Hall’s first love. When visiting her cottage in Dorset, which has several rooms and garden buildings dedicated to tile production, one is immediately struck by her organic relationship to her work. Only through such a close personal relationship with the historic methods and materials has she been able to create such accurate Medieval reproductions. It is as though she has been able to transport herself back in time and view the production process through the eyes and minds of our forefathers all those centuries ago.

You can watch Diana Hall describe and demonstrate her working methods at https://www.youtube.com/watch?v=p2hyplcYfBI

 This article first appeared in Tile UK, January 2001

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