For many years kaolin processing was carried out as a craft, this meant excavating the galleries(1) during the winter, accumulating the material on suitable threshing grounds so that it would crumble due to the action of the weather, and then washing it in the washing shops during the other months. This is where the kaolin clay was exclusively washed by hand, as described in specialised publications: from 25 to 70 wooden tubs(2) were placed on the threshing floor of the shop in groups of 5 around a central one called a ’lavadora’, which was filled with kaolin clay(3) to about one fifth and then almost completely filled with water. The kaolin was mixed into the water with an appropriate shovel creating the ‘kaolin milk’ which was then transferred to the tubs at the side by means of copper beakers. This operation was repeated several times so that the kaolin pulp would thicken due to the effect of evaporation and filtering. At this point it was cut into slices which, having been left to dry in the sun under characteristic driers called ‘casoni’, produced the ‘ingots’ ready to be sold.

The industrialisation of this sector began in the early part of the twentieth century with the setting up of the Caolino Panciera(4) e C. company by Domenico Panciera in 1908, and the involvement of a vast area having an abundant supply of water between the districts of Timonchio di Santorso and Pozzani del Tretto.
In 1909 machinery for washing and pressing kaolin was installed at Timonchio. This consisted of an iron deslimer, that is a wheel having transverse rods rotating within a large tank full of water and kaolin clay to be pulped. The kaolin water poured out of the deslimer and followed a labyrinth of 4 routes along which it deposited sand, it then passed through a series of vats gradually eliminating all the sand to finally deposit the kaolin pulp. This was reduced to kaolin discs by means of a filter-press and then dried in the ’casoni’ by the heat of the sun.

New machinery was also employed in the Pozzani district with the installation of two electric motor-driven deslimers and sanding vats. The wooden tubs were substituted by porous terracotta vats.

In 1925 the installation in Santorso was supplied with a rotary filter to work both the ‘fat’ and ‘thin’ kaolin and the filter presses already there were moved to Pozzani.

Between 1926 and 1927 the plant was further enlarged with the addition of some vats(5), another two filter presses and also the construction of a Pfeiffer and Muller type oven for rapid drying of the pressed kaolin.

During the same period (1926) a chile mill having a Dorst wind separator was installed in Santorso, this could produce from 100 to 200 quintals of extremely fine kaolin powder a day.

A complete section was also installed for the dry processing of the raw material, which consisted of two Gallardi mills with breakers, elevators, air separators and storage rooms, capable of providing 3 tons of the finished product in 24 hours.

The Caolino Panciera e C. company closed down in 1983, and during the last few years at least the mining of the mineral has been resumed thanks to the Emilceramica company in Sassuolo (Modena).

In the district of Timonchio di Santorso there still remains obvious evidence of this vast complex, such as structures and some machinery(6) (for example: grindstones, chile mill and Dorst wind separator) for the washing plant and kaolin grinding, as well as the store(7) for the finished product; while at Pozzani one can still see: the areas used as offices and workshops, the kaolin washing vats(8), the drying oven, the rotary mill(9) for grinding the mineral and the Vittoria plant(10). However, the ancient symbols of kaolin processing, which distinguish the hilly countryside of Tretto, are doubtless the characteristic wooden shelving of the driers(11) with their sloping roofs supported by stone and terracotta or cement pillars as well as all that is left of the kaolin duct.