What sort of clay is used within porcelain tiles?
Porcelain tiles have been in use for a few centuries now, as wall cladding, flooring, work surfaces, patio ground, house decor, and many more functions. This is because porcelain has developed very much with technology, so that now it holds many characteristics and functionalities that make it suitable for such uses. They are very similar to ceramic tiles, however there are a few differences in their manufacturing processes, which give them each certain distinctive specifications. For most people, porcelain tiles are the better option for fulfilling their needs and requirements.
Raw Materials
White clay is the main raw material that makes up porcelain, which is more commonly known as ball clay or China clay (or Petuntse as some may know it as). This type of clay consists mainly of hydrous Aluminium Silicate and Kaolin molecules (compound that is similar to Aluminium Silicate but with a hydroxide molecule within its chain instead of water that makes the Aluminium Silicate a hydrous molecule once mixed in with it and bound to it). Feldspar is also used within the porcelain mixture, and it is a substance formed of flint with Aluminium Silicate. Flint is a type of hard Quartz, and so this allows feldspar to function as a flux within the porcelain mixture, meaning that it reduces the temperature at which liquid gas is formed. Additional Silica may also be added into the porcelain mixture, to be used a filler within the compound, in order to conduct heat effectively across the mix.
Clay – Ball Clay
Ball Clay’s exact colour is determined by the minerals, ions and other oxides found within the material. It is called ball clay as it used to be extracted in small cube shapes, but would turn into a round shape after transporting and handling. Clay tends to be extracted using a few different types of mechanical equipment these days, and with regards to ball clay, it is mainly gathered using hydraulic (back-hoe) excavators. Clay is usually found in locations where rivers or streams once flowed, whereby as ingredients of soil (such as minerals, dead plants, dead animals, etc.) experience the pressure of water flowing on top of them, they start breaking up into very fine pieces, which forms silt, that is then carried by the flowing water across a certain distance. The distance travelled determines the purity of the silt (how many minerals were picked up and mixed with it on the way), which in turn determines the category within which the clay sits. Clay forms naturally as part of geographical processes, in places where rocks are in regular contact with water, steam or even air, such as rocks near a volcano, where the magma heats up water that flows over the rocks, deeply buried sediments containing pore water, sediments on sea, weathering boulders on hillsides, and there are many more different ways, of which these examples are only the few most common ones.
Primary clay is that which is mainly found in areas with small streams, where the water does not have enough power to push the silt for a very long distance, and so it deposits and forms clay without merging with any impurities, meaning that it tends to be white coloured, and this forms clay such as ball clay, called primary clay – and this is the main type of clay used in porcelain. The differences between porcelain and ceramics start during the process of collecting raw materials, because for ceramics, it is mainly the secondary clay that is used rather than the primary. This kind of clay is found in places that have large rivers or small channels, as these waters are powerful enough to drag the silt for a relatively long distance, mixing it with a wide variety of minerals and other materials, before depositing it to allow the formation of clay, and so this secondary type of clay would be coloured rather than white, and would contain a lot of different materials, which clearly explains why it is also called sedimentary clay.
Refined Clay
Clay used in porcelain is also refined after it is gathered. The term used to describe the process is kibbling, whereby the clay is shredded into much smaller pieces to be used in the mould to form various shapes, sizes, and thicknesses. These refined clays have many benefits of improving quality of the stone, bettering the performance of the production line and reducing the overall cost of the process, and so therefore reducing the end price of the tiles as well. Refined clay may come in two different forms, one is noodled, which is when the clay is rolled into strips and tied around only to be dried, whereas slurried is when the clay is mixed up and kept moist to keep it in liquidy format, and keep it fresh for instant use in the manufacturing process.
Clay Capabilities
Ball clay is used in high percentages within porcelain compared to other materials, and this gives the porcelain its rigidity, because once the porcelain mix has been fired up at very high temperatures at around 1200 degrees Celsius, the ball clay becomes very strong at bonding, and sticks together with the other materials within the mixture very tightly, in order to close up any gaps and seal any pores that may form on the stone due to the heating. This in turn not only allows the porcelain tile to be very strong, but also to be highly stain-resistant, as the porcelain tile becomes very non-porous and so therefore liquids cannot pass through the surface easily at all, so they will not be able to leave a stain within the stone.
We can see then that clay is a vital player in determining the functionality of the porcelain, and because of the clay that is specifically used in porcelain, those kind of tiles are very suitable for use in terms of flooring, wall cladding and even as work surfaces. This is why we see the numbers of porcelain sales rising dramatically over the years!
