French “barbotine”, it is a type of engobe, porridge or mixture of clay and water with a muddy or almost liquid consistency, used in pottery to join parts of a previously elaborated ceramic piece, whether produced around the lathe or by hand, and to create drawings on the surface of the pieces with an embossed decoration. It has also been used, since the nineteenth century , to decorate porcelain , using the method known as “decoration to the slip”.
The mixture of water and clay that forms at the bottom of the vessel, 2 and in which the potter dips his hands again and again to reduce friction in the turning process, is also called a slip. That bar has received various names depending on the geography: limarcha in Navarra , lime in the Spanish Levante, slime mud in Malaga , lemoxa in Almeria , llamosa in Valencia , “llamuga” in Ibiza , “llemuja” in Quart and palpasa in Andujar
Some sources date to their oldest use around the third century BC , in Rhenish pottery, replacing molded decoration and using a type of sleeve «to decorate the edges of flat containers with small flowers and other designs»
Throughout history, man has been responsible for developing different techniques conducive to the development of domestic appliances. These creations, popular thousands of years ago, remain to this day, but as an interesting decorative element. One of these activities is pottery, the art of designing and creating vessels from clay or clay; it is born in the Upper Palaeolithic, in small representations of maternal divinities, such as the Venus of Dolní Věstonice. Similarly, the oldest vessel known, comes from the Jōmon period – one of Japan’s prehistoric times – of at least 10,000 years. It should be noted that, for some ceramologists such as Emili Francés Sempere, it is necessary to distinguish ceramics, which combines both sculpture and painting, from pottery,
Even so, the materials used in both practices are characterized by being quite similar. In pottery, for example, a mixture of water and clay is used, which has an almost liquid consistency, to join previously made pieces by hand or for decorative purposes, which is called a slip. With the evolution of the techniques used in pottery, for the preparation of this mixture, a chemical process called levigation was implemented, which basically consists of separating mixtures, that is, indicating a dispersion of particles; This is done in order to make the preparation much more resistant and durable. To achieve this, other components are added, such as tannic acid, sodium carbonate or soluble sodium silicate.
In the ceramics industry it is considered of great importance that the slip does not contain lumps, in addition to its density must be adequate to the creation; For this reason, a series of processes are put into practice in which it is sought to measure it accurately. In some areas, in the same way, it is quite common that all the residues that are at the bottom of the vessel and in which the potter introduces his hands be called a slip, to reduce friction when shaping the sculptures.