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.
There are 5 steps in the ceramic tile manufacturing process: Mining, Blending and
Mixing, Pressing, Glazing, and Firing.
Step 1 is basic and organic.
The process begins with the mining of the raw materials, which is a mixture composed
of mostly clay and minerals.
Step 2 transforms mud into fine sand.
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 the result? A fine clay powder that feels like warm, fine sand.
Step 3 sees a form take shape.
Next, the clay is pressed or formed into a tile shape. These pressed tiles are called
green tiles at this stage.
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 shaped versus pressing the tile.
However, pressing is the more common method used today. And after the green tiles
are formed they are dried to remove some of the moisture.
Step 4 is the glaze phase.
It’s the next step in the manufacturing process for those tiles that will
have a glaze.
If the tile is to remain unglazed it skips this step and goes directly to the firing
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.
Step 5 really heats things up.
The ceramic tiles are now fired in the kiln at temperatures around 2000 degrees
Tiles that are fired once after the glaze is applied are called monocoturra tile
or single fired.
The other type is called biocuttura or double fired tile. Biocuturra
tiles are first fired after the green tile is dried and then fired again after the
glaze is applied.