The mill

The raw clay is crushed in a mill and reduced to fine dust.

The screen and the iron removal

It then passes through a screen to remove any large particles before magnets are passed through to remove all traces of iron.

Manganese

Manganese is added at this point if grey clay is required. Manganese is a powerful natural dye that changes the structure of the material.

Wetting

Depending on the chosen technique for making pots a predetermined amount of water to make it more or less malleable. For example, the clay for the pressing require 10% of its volume in water, while the clay for the manual or centrifugal molding require in 20 to 30%. At this point, the clay is perfectly malleable but in an unusable state.

Grog or chamotte

Pure clay provides excellent plastic qualities but has structural weaknesses. This is why we add an additional mineral component called the grog. This is a volcanic rock gravel whose grains are 2 to 5 mm in diameter. This very hard and dense rock (0% porosity), also known as Ophite, is extracted and prepared in a different quarry.

 Thanks to its physical properties, the chamotte will serve as internal structure to clay in the same manner a spine does to a body. Unlike pure clay that retracts when drying and expands in the kiln, the chamotte is highly stable and significantly reduces the phenomenon of this expansion and retraction of the clay. The other main advantage of grog is that it greatly increases the robustness of the end product and its resistance to frost.

There is 20 to 30% grog in the final blend, depending on which type of piece the clay is destined to make.

Extrusion

This is the last stage of  preparing the clay before shaping, during which air is extracted leaving compact and dense bars of clay to be used by the potters.