Raw Zellige Preparation: From Clay to the Final Piece
Raw Zellige consists of uncut square pieces measuring 12×12 cm, prepared for the cutting process. In this article, we will explore in detail the steps involved in Moroccan Zellige production, a traditional mosaic art form that is characterized by precise stages throughout its creation.
Choosing the Clay and Preparing It for Zellige Making
The process of making raw Zellige starts with selecting the best types of clay, which are gathered from carefully chosen locations and mixed with water in a large trough until it becomes a semi-liquid consistency. This process helps to remove impurities and stones, which settle at the bottom of the trough due to gravity. The impurities are separated because materials like calcareous stones can crack during firing, damaging the pieces or creating imperfections that affect their quality. The clay slurry is then passed through a fine sieve into an adjacent trough to ensure it is free of floating debris.
Initial Drying of the Raw Zellige
After several hours of settling, the clean clay sinks to the bottom while water floats above it. A hole is made in the side of the trough where the water meets the clay, allowing the water to flow out and leaving the clay behind, which remains pure. This method is effective in preventing the mixing of water with clay during the filtration process. The clay is manually placed and pressed into a mold with specific dimensions (25 cm in length, 13 cm in width, and 2 cm in thickness) to ensure uniformity in the size of the pieces. This process is carried out in a large open area under the sun, ensuring that the ground is sprinkled with moist Fine wood sawdust.to preventing the pieces from sticking to the ground.
Cutting and Shaping the Zellige
At this stage, artisans bring these pieces for the final shaping process. Using traditional tools, the pieces are struck on a flat surface to smooth surface with a mallet to ensure good cohesion and increased hardness. The striking process helps to level the surface of the clay pieces and fix the remaining sawdust stuck to the back. A 12×12 cm square mold is placed over the piece, and excess edges are trimmed with a special tool to ensure the piece is perfectly sized. Each piece from the first mold produces two pieces from the second mold.
Final Drying of the Zellige and Arrangement in the Kiln
After cutting, the pieces are dried again under the sun until they reach the final drying stage. They are then collected and arranged inside traditional kilns vertically, where three edges of each piece meet to form triangles. This arrangement helps prevent the pieces from sticking to each other during firing and ensures heat circulates evenly among the pieces. Traditional kilns typically hold between 10,000 and 15,000 pieces, and the firing duration depends on several factors such as weather, kiln size, and piece quantity.
Glazing and Second Firing of the Zellige
After the first firing is complete, the pieces are removed and left to cool. The Zellige glazing method in Fez involves immersing each piece by hand in containers filled with metallic pigments. In Marrakech, modern tools are used to spray the glaze onto several pieces at once. The back side of each piece is left unglazed to maintain its rough texture, This rough texture helps the pieces adhere better to the materials used during installationذ.
The pieces are then returned to the kiln for a second firing to set the glaze and ensure uniform color across all pieces. The second firing lasts approximately the same amount of time as the first. Afterward, the pieces are carefully sorted, and any cracked or damaged pieces are separated. The good pieces are packed in bags or boxes to be transported to engraving and cutting factories.
Firing Temperature and Its Impact on Zellige Quality
The firing temperature plays a critical role in the quality of Zellige, as it affects the density of the pieces and the uniformity of the colors. It is important to adjust the concentration of metals in the pigments according to the firing temperature to achieve the desired color.
Ceramic Pigment Table and Their Components
| Pigment Type | Main Components | Firing Temperature (°C) | Notes |
|---|---|---|---|
| Blue | Copper oxide, Cobalt oxide | 900-1050°C | Produces a dark to sky blue color depending on concentration |
| Green | Copper oxide (CuO) | 850-1050°C | Green color may be affected by other chemicals |
| Yellow | Chromium oxide (Cr2O3) or Iron oxide (Fe2O3) | 800-1000°C | Yields a light yellow or golden color |
| Red | Iron oxide (Fe2O3) or Copper oxide (CuO) | 950-1100°C | Produces a bright red or reddish color depending on concentration |
| Orange | A mixture of Iron oxide and Chromium oxide or Copper oxide | 900-1050°C | A blend of colors producing an orange hue |
| White | Tin oxide (SnO2) or Zinc oxide (ZnO) | 850-1000°C | Used to enhance gloss or achieve pure white color |
| Black | Manganese oxide (MnO2) or Iron oxide (Fe2O3) | 950-1100°C | Produces a deep black or gray color |
| Brown | Iron oxide or Copper oxide | 850-1000°C | Ranges from light brown to dark brown |
Firing Temperatures for Different Types of Clay
| Clay Type | Firing Temperature (°C) | Notes |
|---|---|---|
| Red Clay | 800-1000°C | Achieves a smooth, sturdy texture at this temperature |
| White Clay | 1000-1200°C | Requires higher heat to increase durability |
| Stoneware Clay | 1200-1300°C | Produces a hard, stone-like clay |
| Porcelain Clay | 1200-1300°C | Used for producing white or glazed ceramics |
Conclusion
By following these steps, durable Zellige pieces with perfect colors are produced, ready for the next stage, which is cutting and engraving. These stages demonstrate the complexity and craftsmanship of Moroccan Zellige production, which requires collaboration between skilled artisans at each stage to ensure the quality of the final product.