How Ceramic Wall Tiles are Made
Ceramic wall tiles are a stylish and durable wall covering that are popular throughout the world. Tiles bring colour and glamour to a room whilst being capable of waterproofing your walls, they are easy to keep clean and if fixed well have a long life span. So, how is the humble tile made in high yield factories today?
Most ceramic tiles are manufactured using a mixture of raw materials including ball clay, china clay, sand and limestone. Some manufacturers combine this “recipe” with some crushed waste material called pitcher; this is basically any waste fired tiles crushed down to form a course powder. This addition is added to the other raw materials and is a great way of recycling any product that has been scrapped whilst it also provides more stability to the tile body. These raw materials are mixed with a specific quantity of water before being transferred to a mill which turns the mixture over and over with some heavy ceramic balls. The end result of this process is called “slip” and it is the “slip” that is used to form the biscuit body (the tile itself).
What Happens Next?
The slip is usually dried out using a large drier, this is a machine that blows the particles of the slip around whilst it extracts the moisture and expels it through the factory chimney as steam. It is important that a small percentage of the moisture content is left in the tile body so that it can be easily pressed into shape. After the drying process has taken place, the powder that is created (seems completely dry to the touch but it does still have a percentage of moisture remaining) is compacted with pressurised presses to mould the powder into tile shaped body that at this stage is very fragile.
Now the materials are pressed into shape and are holding together, it is now imperative that the remaining moisture is removed at this stage. This process occurs when the pressed tile body is sent on a conveyer belt through a drier. If the drying did not take place, the water content would mean that the tile body would explode as soon as it reached the high temperatures of the kilns.
Into the Kilns
The large, long kilns have a series of rolling rods that run through them enabling the tiles to be transported through from start to finish. At the beginning of the kiln the tiles will be subjected to temperatures of around 200°c and by the time they reach the peak temperature of around 1000°c they will have been in the kiln for up to half an hour. As they reach the end of the cycle the tiles will need to be cooled gradually as failure to do this can result in cracking (known as thermal shock).
Time to Make them Pretty
Depending on the raw materials that have been used the tile biscuit will often appear nearly white unless sand stone has been added to the body and if this is the case it will appear more red in colour. The biscuit is visible on all glazed tiles simply by turning them over and looking at the back.
At this stage the tile biscuit will need to be glazed. The glaze is the glass type substance applied to ceramic tiles to waterproof the front of them, give them integrity and their attractive finish. Before the glaze can be applied the tiles are first misted with a fine spray of water to help the glaze to adhere properly.
Next, comes the base coat which is referred to as “engobe”, this is a slip type substance that gives the tiles better texture, the “engobe” maybe white or coloured depending on the colour of the tile body. After the engobe has been applied the tile edges are cleaned before a layer of glaze is added.
At this stage different manufacturers adopt a different process for applying the decoration to the product. One popular method is to roll over the tiles using a roller to build up the pattern, the colours used on the roller look quite dull until the tiles are fired when the full depth and vibrancy of the pattern is revealed.
After the glaze and decoration are applied to the tiles they go back to the kilns where they are fired for a second time. They emerge from the second firing process a strong and resilient end product. They will be left for a short time so that they are completely cooled before going through the quality checking process where they will be sorted, boxed and wrapped ready for going on sale.
The manufacturing processes that different tile companies use vary from organisation to organisation but this article sets out to give you an overview of the processes involved in creating some of the most stunning home-ware products that customers will cherish for years to come. So next time you are sloshing around in your bathtub spare a thought for your tiles and just what they went through in the manufacturing process.