How Ceramic & Porcelain Tiles are Made

The process of making ceramic tiles is ancient, and the resulting benefits are many: beauty, durability, practicality and versatility.

Knowing ceramic construction also helps you better understand and evaluate its performance aspects, and will help you choose the right tile for your application and your budget.

Earth and Fire.
The main ingredients and the general manufacturing process of ceramic tile has barely changed throughout the centuries.

All ceramic tiles are created from natural products extracted from the earth, shaped into tiles, and then fired in kilns at extremely high temperatures.

Classes of Ceramic Tile.
There are 2 main types of tile construction: glazed and unglazed.

Glazed
When you look at a glazed tile from the side you can see 2 layers. The body of the tile, or largest layer, is called the bisque. The top layer is called the glaze.

Glazed tiles have a hard non-porous, impermeable surface after firing. They are more stain resistant than unglazed tile and are easy to clean, Something to consider for those more active areas of your home like the kitchen and baths.

Unglazed.
Unglazed tiles add a whole different beauty to your home. They are solid colored all the way through and do not have a top layer of glaze. This is often referred to as through-body construction.

They have no additional surface applications and are typically more dense and durable than glazed tile. Thus they are more suitable for interior and exterior applications where wearability is a concern.

If your home has areas of heavy activity or kid "zones," unglazed tile may be just the answer.

Making Ceramic Tile.
There are 5 steps in the ceramic tile manufacturing process: Mining, Blending and Mixing, Pressing, Glazing, and Firing.

1) Mining.
The process begins with the mining of the raw materials, which is a mixture composed of mostly clay and minerals.

2) Blending and Mixing.
The clay and mineral mixture is blended and mixed into a semi fine powder. Water is added to form a wet slurry or mud-like consistency. Then the slurry is pumped into a large dryer and comes out feeling like a warm, fine sand.

3) Pressing.
Next, the clay is pressed or formed into a tile shape. These pressed tiles are called green tiles at this stage. After the green tiles are formed they are dried to remove some of the moisture.

(There is also another method called extrusion, which can replace the pressing step. Extruded tiles are formed by forcing the clay material through a mold for the desired shape versus pressing the tile. However, pressing is the more common method used today.)

4) Glazing.
The glaze liquid is prepared from a glass derivative (called frit) and colored dyes. The glaze is applied by either a high-pressure spray or is poured directly onto the tile.

(Obviously, this step is skipped for unglazed tile.)

5) Firing.
The ceramic tiles are now fired in the kiln at temperatures around 2000 degrees Fahrenheit.

Note On Glazed Ceramic: Tiles that are fired once after glazing are called monocoturra tile or single fired. Tiles fired both before and after the glazing process are called biocuttura or double fired tile.

Porcelain Tile
Aside from the glazed and unglazed ceramic tile, there is another, closely related category that continues to gain popularity - beautiful, elegant and strong porcelain tile.

Porcelain tile is made from a blend of fine-grain clays and other minerals to produce a very dense body and is fired at a much higher temperature than regular ceramic tile. These differences make porcelain tile more resistant to moisture, staining, and wear than other tile products.

Their high performance and low water absorption ratings of less than 0.5 percent make these tiles a worthy choice for both the interior and exterior of your home. The low water absorption rate makes porcelain tiles frost resistant.

Glazed Porcelain.
Glazed porcelain has "filled in" microscopic holes that can be present in unglazed tile, are very durable and a little easier to maintain. However, the color in the glaze layer may be different from that of the body.

Unglazed Porcelain
Unglazed porcelain is referred to as "through body" where the color on the top goes all the way through the tile. Due to this characteristic, unglazed porcelain tends not to show wear as much. Finally, unglazed normally has better slip resistance.

Classes of Ceramic and Porcelain Tile
Not all ceramic tile is suitable for each area of your home. There are five classes you should know about.

Class 1: no foot traffic-wall use only.
These tiles are suggested for interior wall applications only and not for the floor.

Class 2: light traffic.
These tiles are suggested for light residential use for bathroom flooring, countertop and walls.

Class 3: Medium commercial & all residential.
These tiles can be used for residential floor and wall applications including bathrooms, kitchens, foyers, dining rooms and family rooms. They're a good all-around performer.

Class 4: moderate to heavy traffic.
These tiles are recommended for residential, medium commercial and light industrial floor and wall applications including shopping malls, offices, restaurant dining rooms, showrooms and hallways.

Class 5: heavy/extra heavy traffic.
These tiles can be installed anywhere. They will hold up in floor and wall applications at airports, supermarkets and subways. Tile doesn't get any tougher.

Other Ratings
You may also see a rating for Slip Resistance, which is measured by its Coefficient of Friction (COF). The higher the COF the more slip resistant the tile. This measure is particularly important when selecting a floor tile for areas that get wet, such as your shower or bathroom floor.

Other ratings listed by the manufacturer might include: scratch resistance, moisture absorption, chemical resistance and breaking strength.