Clay as a raw material and mineral can be found almost everywhere in the world.
In industry and pottery, clay can be used as natural, pure and unadulterated, or seriously processed, with a host of additives that add completely new properties and qualities to the quality of the resulting products. It can be porcelain products, earthenware, some kind of construction mixtures, mixtures for finishing and so on.
We will not consider clayey raw materials, which are not used due to rejection of water, but only those, which in contact with water form necessary in our case sour creamy mass or dough. These are actually clays and kaolins.
And then these formations can be divided by the following properties - first of all by the proportion of alumina (from 10-15% to more than 40%), from acid and semi-acidic to basic and high-basic in the fired state. Then the raw materials are classified by the degree of refractoriness: starting from the lowest temperature level and going from 350 to high-temperature resistant (over one thousand degrees) and refractory, which can withstand temperatures up to 1580 degrees.
Another very important property of raw materials is their plasticity and the ability not to lose their cohesiveness when adding fillers, usually quartz sand. The most plastic natural material allows for adding up to half of the sand, without losing its properties. The second category is clay, which can quite tolerate the addition of twenty to fifty percent of sand, and the weakest, the so-called "lean" - a material that can take without loss of plasticity only 10-15 percent of the sand.
Of course, few potters will look at the percentage of additives. As a rule, masters proceed from what they want to produce, from the quality of the resulting products. Industry offers a wide range of ceramic clay on the market, it is only important to know what type it can be attributed to. Porcelain clay, earthenware clay, unfired clay and red-burning clay are the ingredients that can be used for handmade ceramics and for making pottery and spinning shapes on potter's wheels. In industrial production and in the construction of buildings, their cladding, laying underground utilities, special pipe, clinker, capsule and terracotta clays can be used.
The most massively known example in history of the use of natural clay on an industrial scale is the continuous production of clinker bricks and tiles by the German company Feldhaus for more than one hundred and fifty years. The refractory clay from a unique deposit, which naturally contains feldspar, enables the production of bricks with a minimum residue of bound water. The result is breathable, durable bricks and tiles of special strength.
In Europe, clay has been used everywhere for a long time. It is a source of national pride for many countries and peoples, and in each of them, if we wish, we can find ancient artefacts which have made life more convenient, comfortable and safe for ordinary people for hundreds or even thousands of years.