Tile
A tile is an artificial stone piece with varying lengths and widths, usually with a thickness of a few millimeters. One side of it has a glazed surface that is entirely smooth and polished. Tiles are ceramic products that have a significant role in building structures such as bathrooms, toilets, kitchens, and public washrooms.
Tiles are used for interior and exterior decoration and also for hygiene and moisture insulation.
The term “tile” is derived from the name of the city of Kashan, which was famous for its pottery industry in early Islamic times.
Tile Production Process
The first stage is the selection and preparation of materials.
The materials used in tile production are clay-based, with 20-25% of it consisting of silica.
Initially, any excess materials, debris, and stones are removed from the clay.
After washing and separating the excess particles and homogenizing the clay, it is exposed to air. Then it is ground until it becomes a uniform powder. The higher the quality of the clay, the more attention is paid to its preparation.
The prepared clay is immediately transferred to other halls for further processing using conveyor belts.
Clay Preparation
Clay preparation involves mixing the prepared materials with water, which gives the mixture plasticity and allows it to be shaped.
When mixing water with clay, care is taken to ensure that all clay particles come into contact with the water.
To prevent the piece from shrinking and warping during firing, a small amount of ground flint is added. To prevent dark brown discoloration caused by the presence of iron oxides in the clay after firing, about 0.5% chromium oxide is added.
Molding
Once the clay is approved by the lab for material composition and distribution, it is molded.
High-quality tiles are molded in a vacuum, which increases density and strength.
Shaping is mostly done by pressure and pressing. The press plates have features that prevent the clay from sticking to them. The water content of the clay should be enough to give it the plasticity needed for easy molding, while also ensuring that the piece retains its shape after pressing.
Drying
If the piece is not dried properly or dries too quickly, it will crack or warp. After pressing, if the piece is exposed to dry heat, the outer surface will dry too quickly.
For high-quality drying, a warm air tunnel is used.
To prevent cracking, wrinkling, and surface warping, the air at the beginning of the tunnel is maintained like the outside air.
In the middle of the tunnel, the temperature reaches the necessary maximum, and at this stage, all the physical water evaporates, and the piece dries completely.
Throughout the tunnel, both humidity and temperature are monitored.
Firing
Ceramics are fired in two stages. First, the dried ceramic piece is sent to the kiln for its initial firing, typically in tunnel kilns. The temperature is gradually raised to 100°C to evaporate physical water, and then the kiln temperature is increased until all moisture is evaporated at 250°C. At 450 to 600°C, the chemical water evaporates, and at 800°C, all organic materials in the clay are burned away, and the piece enters the vitrification stage.
Glazing
After the first firing and before the piece is fully vitrified, it is removed from the kiln and glazed. If the tile has a design, the specific designs, made of glaze, are applied before glazing. Then the glaze is sprayed onto the piece, and the glazed pieces are placed on special carts and returned to the kiln for the second firing. The glaze melts under heat and penetrates the pores of the ceramic, fusing with it.
Once glazed, tiles are graded and then packaged for the market.
Components
A tile consists of two parts:
- The ceramic body, which forms the structural part of the tile.
- The glaze on top, which is a glassy material covering the surface.
One of the most critical factors in tile production is ensuring that the coefficients of expansion for both materials are the same.
Types of Tiles and Ceramics
Wall Ceramic: These tiles are designed for wall installation with a glossy finish and less durability compared to floor tiles. They come in various sizes and designs.
Floor Ceramic: Commonly referred to as “ceramic” in everyday language in Iran, these tiles are more durable in both body and glaze compared to wall tiles.
3D Ceramic: A new generation of tiles, using advanced printing technology and optical illusions, has added beauty and a unique touch to the tile and ceramic industry.
Porcelain Tile: Known as the third generation of ceramics, porcelain tiles offer superior density, strength, and resistance due to high-temperature firing.
Applications
Tiles are used for interior and exterior decoration (especially in religious places) and for hygiene and moisture insulation. Tile sizes vary from 2×2 cm to 50×50 cm, 40×80 cm, and 30×90 cm. These tiles can depict a painting when installed. Tiles must endure sudden temperature changes from 100°C to 20°C without showing any cracks on the surface or glaze.
Wall tiles are commonly used in kitchens, bathrooms, and hygienic environments to maintain cleanliness and moisture control. Floor tiles, due to their wear resistance and high thermal and electrical insulation, are used in kitchens, bathrooms, laboratories, laundry rooms, and chemical factories.
Tiles must also have smooth edges and sharp corners.
Types of Tiles by Structure
Porcelain Tile: Fired at very high temperatures, porcelain tiles are denser, stronger, and more durable than other tiles.
Cement-Based Tile: These tiles are formed by pouring the mixture into molds and are either kiln-fired or air-dried. Sealing them after installation increases resistance to stains.
Mosaic Tile: Available in porcelain or ceramic and typically made in 2.5 cm squares, mosaic tiles can be installed individually or pre-installed on plastic or paper sheets. They come in glazed and unglazed varieties.
Paver Tile: Similar in appearance to brick but thinner, these tiles are used for floors, patios, and sometimes in bathrooms. They require sealing after installation.
Brick Tile: Used for specific decorative purposes, these tiles resemble bricks and can be arranged in unique patterns.
Glazed Tile: Made by applying a glass-like surface after firing, these tiles are easy to clean and ideal for bathrooms, kitchens, and other spaces.
Unglazed Tile: Used mainly in commercial areas due to their durability and affordability.
Mexican Tile: Also known as Saltillo, this tile is naturally air-dried and not kiln-fired. It has a distinctive appearance and must be sealed after installation.
Ceramic Tile: Made from clay or similar minerals, ceramic tiles undergo both forming and glazing at high temperatures.
Source: Best Tile and Ceramic – Types of Tiles and Ceramics