Ceramic tile is clay that is formed, glazed and baked. Sounds simple, right?
Very little has changed about this recipe throughout history, except for the methods of production. Ceramic tiles were ones created by hand. The wet clay would be molded into shape and then dried out in the sun or baked in a brick kiln. There are a few ceramic crafters that prefer not to use the help of machines, and choose to make their unique artisan tiles themselves. The results are stunning, though it’s an admittedly slow process. Nowadays, manufacturers use a method known as dry pressing (or dust pressing). It’s a process that requires a lot less manual effort, but can produce constantly elegant and perfect batches.
As for the formula, there is no one magic combination of ingredients for ceramic tiles, but almost all manufacturers use common elements, such as clay, sand, feldspar, quartz, and water. What comes next is the mixing. The ingredients are grounded into what we call a “body slip.” Essentially, a body slip is used to help manufacturers tell the difference between the body of the tile and the glazed surface. The body slip is then placed in a heated dryer to reduce the moisture content significantly, until it is practically a powder.
At this point, manufacturers rely on dry pressing to set the body slip into shape. They’ll use a large press powered by either hydraulics of electricity to force the powder into shape, ranging from the popular rectangular tile, to different geometries, like ovals, diamonds, and hexagons. This new form is called the bisque, and it’s dried again to remove more moisture that might have been left in the tile.
Although the bisque has a set shape, the structure and the finished will not be stable until it’s baked. Manufacturers today have long left the standard kiln behind, and have opted for what’s known as a continuous kiln, which takes the tiles through a continuous roller-hearth that maintains a constant application of heat on the product. Artesans still heat their tiles the traditional way, by leaving them in the kiln for a certain amount of time. The continuous kind, however, is process that gradually increases and decreases the temperature of the tile through its movement in and out of of the kiln. This allows the kiln to maintain a temperature throughout the entire production process, and allows the tiles to be fired a lot more quickly, reducing heating times from about 7 hours to less than an hour.
Depending on the purpose of the tile, the product may have to be fired more than once. Such is the case for tiles that are glazed with a variety of colors or an intricate design, which are baked with the bicottura method. A new glaze is applied with each individual firing, until the pattern is complete. In the case of floor tiles, multiple firings might reduce the strength of the final tile. The monocottura method gives the tile a greater sturdiness, since it is only fired once.
After being fired, the tiles are ready to be sent to suppliers, or to a retail store. And after that, the tile is ready to make your project special and spectacular.