Ceramic production

All ceramic production has burnt clay (Greek: keramos) as its most important raw material. By adding various substances to the clay, it is possible to make blends that result in various kinds of ceramics. Ceramic products can be divided into a range of different categories. The following main categories can be useful: brick, faience, creamware, stoneware, bone china, and porcelain.

Besides faience, the factory in Egersund produced stoneware, creamware, and a special type of porcelain with added corundum. With small variations, the production process for these three types of ceramics is the same.

All ceramic production can be separated into two distinct phases. During the first phase, the objects are given shape from a plastic clay mass. They are then fired at approximately 1000 to 1200 degrees Celsius. During firing, a range of physical and chemical changes occur. Water is driven out of the clay, leading the objects to shrink. At the same time, the material is transformed, from a fragile and loose compilation of minerals, to a hard and firm material. At temperatures above 1000 degrees Celsius, the various raw materials melt together to form a hard mass. This gives the objects completely different properties than the raw materials. Firing is irreversible. It is not possible to convert the fired product to raw materials again, as in the metal- or glass industries.

As mentioned, clay serves as the basis of production. The factory got its clay from England, transported by boat. The clay was brought ashore in wheelbarrows and stored in large cisterns.

Svingbru for jernbanen og kullager ved Egersunds Fayancefabriks Co. på 1920-tallet.

The railroad swing bridge, the coal storage, and the factory in the 1920s.

Coal was used when firing products and for heating the factory. It was transported by boat in bulk from England. The coal was unloaded on the upper side of the swing bridge above Lundeelva (the Lund river). The swing bridge put a size limit on boats coming in to deliver goods. The unloading was done by hired workers. The clay used at the factory was mixed with Danish flint and Norwegian quartz.

The clay was transported from the storage silos to be mixed with several additives. The two types of clay – ball clay and china clay – were mixed with quartz, flint, and broken pieces of unglazed ceramics. The flint had to be fired prior to use. The stones were stacked in layers, along with wood, in a flint oven. The flint cracked into pieces when heated. Crumbled flint was then mixed with pulverized unglazed ceramics and stored in silos. From there, the mixture was transported to ball mills, where it was ground into a fine blend, ready to be mixed with clay.

After being processed in the ball mills, the flint and quartz mixture had a milky consistency. It was mixed with clay in large mixing vessels, driven by rotating propellers.

From the mixing vessel, the clay went through a pipe and into the filter press. Here, water was pressed out of the clay through pieces of canvas. The press was operated by muscle power, which made the pressing process hard work. A lot of water needed to pressed from the clay to gain the desired level of moisture. After being pressed, the clay went through its final preparations to ready it for use in the workshops.

Two kinds of clay were used. One was a thick and viscous mass, pressed into oblong pieces. The other was a thin, watery paste called «slikk», used for clay casting. Working with the mixing vessels was considered the hardest and dirtiest kind of work in the entire factory.