Sgraffito is a pottery decorating technique, which is done by scratching or incising through a colored slip or glaze to reveal a different color clay underneath. 1) This usually means a white slip over a red clay. The designs can be done in a linear pattern or the background is cut away to reveal the design. 2) “Sgraffito”, comes from the Italian verb “sgraffiare’, which means to incise. 3)

Sgraffito was first found in China 4) during the Sung Dynasty (AD 960-1223), swiftly moving into Islam and Byzantium. Sgraffito designed pottery was most popular in Byzantium 5) in the 11th to the 14th centuries. The technique is found on dinnerware, such as, plates, bowls and jugs. During the early 11th to 12th centuries one color glaze was used over the sgraffito design, either in yellow-brown or green. 6) Later in the late 13th and 14th centuries two colors of glazes were used. 7) The sgraffito designs represent a variety of motifs. Animals and birds, people doing various activities, spirals and lacing, as well as vegetative type motifs were most common. Some of the designs were meant to mimic metal ware. Common people could afford the clay wares, being less costly to make than the metal dinnerware. Trade routes to Italy and further into England spread the technique of Sgraffito.

The Tring Church tiles 8) are the only known examples of sgraffito tiles from 14th century England. 9) This technique proved to be too time consuming and inlaid tiles 10) were the preferred method of tilers at that time. 11) The designs for the sgraffito tiles were given to the tilers by the illuminators. The illuminators would give the tilers a “cartoon” drawing. The real manuscripts were not allowed near the clay. Only the most skilled craftsmen would make sgraffito tiles. These tiles would be used on walls rather than on floors. The sgraffito tiles were expensive to make, being more labor intensive.12)

The medieval process of making sgraffito tiles begins with rolling out of the tile in red earthenware clay. This was done on a sanded surface. The Tring tiles were 1.4 inches thick. This is about the same thickness of the floor tiles from this period. The tiles were probably cut out by using a form to make the tiles uniform in size. Liquid white clay (slip) is applied to the red clay tile using a brush. The white slip is put on in layers, alternating the layers, over the entire tile and then allowed to dry. The cartoon drawing was then scratched into the tile using a stylus to the red clay body. A gouge was used to remove the white clay to reveal the red clay background. A dry brush or soft cloth can be used to brush away the dry white clay “clippings’ accumulated. The tile was then dried slowly. The medieval tilers had drying sheds that they used to dry their tiles complete with hearths to aid in the drying. The tiles were then glazed with a clear lead glaze, dried and then fired in a kiln using wood as the fuel. Tilers in this time period fired their tiles once. Glazing and bisque firing were done all at once. The clay bodies in England contain iron; as a result the clear lead glaze turned yellow over the white clay and brown over the red body. 13)

The modern processes are the same until it comes to drying and glazing. The drying technique of putting plaster wallboards on the top and bottom of the tile works for me. I came across this in Frank Giorgini’s book, Handmade Tiles. 14) This draws moisture from both sides at once, reducing the chance of the tile warping. A plastic bag is then placed over the wallboard and tile to allow the tile to dry slower. The tile is left in the bag for a week. Then the tile is placed on a metal rack open on the top and bottom to allow for air flow. This time the tile is not covered by the plastic bag. After the tile is bone dry, fire the tile to bisque. Depending on the clay used this can be from cone 06 to about 04. Anything fired above cone 04 is considered to be stoneware. The medieval European potters didn’t have the technology to fire at stoneware temperatures. I bisque fire the tiles before glazing. (The medieval tiler did the bisque and glazing together, resulting in a much higher breakage rate, along with toxic fumes and glaze defects associated with single firings.) I then glaze the tile with a clear lead-free glaze and returned the tile to the kiln for a glaze firing. Potters of other forms besides tiles did seperate bisque and glaze firings according to Piccolpasso in his book from the 1500’s.15)

Suggestions for your own tiles: Use grogged clay or add grog to the clay. The grog will help the tile dry evenly and warp less. Addition of sand can also be helpful. The medieval tiler added sand for this reason to their clay. I also have used a yellow slip instead of the white, ( this will give the effect of the yellow cast due to the lead in the glaze, without using lead based glazes.) Glaze the tile with clear glaze over top of the yellow slip also.

Glossary of Terms

Bisque firing: Also referred to as “biscuit”. This is the first firing of clay without a glaze coating. The clay will still be porous after bisque, but will not be able to revert back to liquid state.

Bone dry: State of dryness of clay. It is when the clay has changed color and it is no longer wet to touch. The clay will be warm to touch. Before that state, the clay is cold to touch as the water is still evaporating. (What is referred to as “leather hard”.)

Byzantium: Encompasses the modern day countries surrounding the Mediterranean Sea (Northern tip of Africa, Egypt, Israel, Lebanon, Syria, Turkey, Greece, Cyprus, Albania, Bulgaria,Yugoslavia and Italy.)

Cone: “Pyrometric cone”, small triangular, elongated pyramids made from a mixture of ceramic materials. They are placed in a kiln before firing takes place. The cones are designed to bend when a certain temperature is achieved. (Cone 06 bends at 1830 degrees Fahrenheit, cone 04 will bend at 1940 degrees.)

Earthenware Clay: Low fire earthenware clay was most common clay used in the medieval period. Generally red in color, but white, green, gray, yellow and brown were also found.

Firing: (Fire) Heating pottery in a kiln or open fire pit, to bring the clay to maturity. (Maturity refers to the temperature and time in firing at which a clay or glaze reaches the desired hardness and density or glaze has melted onto surface.)

Glaze firing: Usually done after a bisque firing. The glaze is applied to the bisque ware and returned to kiln. Glaze is a vitreous (Glassy) coating that has been melted onto the surface of a clay body in a kiln. The glaze surface of the clay is now no longer porous.

Gouge: Wire loop tool used for sgraffito decorating. (The gouge used on the Tring tiles were 4mm (1/4 inch) wide.)

Grog: Crushed or ground particles of fired clay added to the clay to help in dryness, adds texture, durability and reduces shrinkage.

Inlaid tiles: A depression is made in the red clay tile and the depression is filled with a white clay slip.

Islamic Pottery: Encompasses the Arab world; Turkey, Iran and Central Asia.

Slip: Clay that has been mixed with water to a smooth creamy liquid consistency.

Stylus: Simply any pointed object, like a pencil, or a sharpened piece of wood like a toothpick.

Bibliography

Cosentino, Peter, The Encyclopedia of Pottery Techniques. Quatro publishing. 1990.

Dark, Ken, Byzantine Pottery. Tempus Publishing, 2001.

Evans, Helen and Wixom, William D. edited by, The Glory of Byzantium. the Metropolitan Museum of Art, New York, 1997.

Eames, Elizabeth S., English Tilers, University of Toronto Press, Toronto, Buffalo, 1992.

Fournier, Robert, Illustrated Dictionary of Practical Pottery, A & C Black Publishers, 1992.

Giorgini, Frank, Handmade Tiles, Lark Books, 1994.

Papanikola, Demetra, Fofo Mavikiou and Ch. Bakirtzis, Byzantine Glazed Pottery in the Benaki Museum, Benaki Museum, Athens, 1999.

Papanikola-Bakirtzis, Demetra, Eunice Dauterman Maguire, and Henry Maguire, Ceramic Art from Byzantine Serres, Board of Trustees of the University of Illinois, 1992.

Papanikola-Bakirtzis, Demetra, edited by, Everyday Life in Byzantium, Hellenic Ministry of Culture, 2002.

Piccolpasso, Cipriano, I Tre Libri Dell’ Arte Del Vasaio, 1524-1579, (The Three Books of the Potter’s Art), 2 volumes, A Facsimile of the Manuscript in the Victoria and Albert Museum, London, Translated and Introduced by Ronald Lightbown and Alan Caiger-Smith, Scholar Press, 1980.

Van Lemmen, Hans, Decorative Tiles Throughout the Ages, Moyer Bell, 1997.

Watson, Oliver, Ceramics from Islamic Lands, Sheikh Nasser Sabah al-Ahmad al-Sabah, 2004. (Thames and Hudson in association with the al-Sabah collection Dar al-Athar al-Islamiyyah, Kuwait National Museum.)

Wilkinson, Charles K. Nishapur Pottery of the Early Islamic Period, The Metropolitan Museum of Art, New York, (ISBN # 0-87099-076-4).