Manufacture of Inlaid Medieval Tiles The production of medieval floor tiles extended from the mid 13th to the mid 16th century. Owing to the expense involved, the earliest commissions would have been schemes for the paving of royal palaces, the houses of rich laymen, and ecclesiastical and conventual buildings. Medieval tiles have been found at Bridgwater Friary, a Franciscan monastery built around 1245 AD, the remains of which were abandoned in 1538 during Henry VIIIs dissolution of the monasteries. A single tile has been found at the site of St John's Hospital and one at Woolavington. Suitable clays for tile and brick making are found in different parts of the country. Mercia mudstone is a limey kind of clay, generally red or greenish in colour, found from Keynsham to Yatton and also near Wellington. Alluvial clay, formed by deposits washed up or down a river by the tide, were found at Bridgwater, Clevedon, Burnham on Sea and Minehead. Oxford clay occurs in a band from Frome down to Wincanton. Small pockets of white firing (china) clay occur in various areas, and early tilers were able to transport it from not too far away. The secondary clay was probably dug in the late summer or autumn and left to weather during the winter so that the rain and frost could leach out impurities. It was then transferred to a sanded table where it was pounded and levigated and the air was driven out. Unless this was well done there would be cracks and holes in the fired clay. The clay was then forced well down into a sanded form and a taut bow-type wire was drawn across the top to remove surplus clay. The tile was the turned out and left to dry to a firm but pliable consistency. For some tiles tapering and bevelling was used to facilitate the bedding of the tiles in the pavement because of difficulties caused by the variation in the sizes of fired tiles. One such method was to the cut the sides of the tiles at at angle top to bottom. Another method used is shown on the back of Tile 7 and 8. Both show the keying of the tile bases, another aid to bedding and levelling. Usually, as shown by Tile 7, four shell shaped or conical holes were cut out, but occasionally there were five or six smaller ones, or even a single central one. These holes were probably made by inserting and twisting a pointed knife or perhaps a forked stick into the clay base before it had dried completely. The majority of tiles are of the square or rectangular, plain or early (inlaid) two colour types, although decorated mosaic, combed and brushed, and relief and possibly stenciled tiles are present in Somerset. Examples of the combed or brushed method are found on the tile fragments from Bridgwater Friary. The surface of the tile was coated with white slip and the decoration was produced by swirling a brush or comb across it. For the early two-colour (inlaid) tiles, the mirror image of the design was carved in relief and, judging from the variations in depth of the impression the stamp was probably applied manually. For some of the good earlier designs, metal dyes may have been used. The impression left by the stamp was filled with semi-liquid, white-firing primary clay, with the surplus neatly scraped or wiped off so the tiles could be put aside again to dry. Tile 5 in particular shows the use of glaze. Early plain tiles relied on the colour of the glaze to produce a pleasing design. The glaze was applied before any firing took place. Four basic glazes were used: lead, lead with a small amount of copper, lead with more than 5% copper and lead with iron. When lead was applied over a white slip it produced a bright yellow colour. Lead with a small amount of copper produced bright green. When applied over an oxidised clay body lead gave a brown colour. Lead with a small amount of copper gave a deep green colour. Lead with more than 5% copper and lead with iron together gave black.

Tile images can be found here