POTASH alum – Kal(SO4)2.12H2O

History of Potash Alum

The civilizations of the Middle East Mesopotamia, Egypt and later Greece were the first to use Alum, which, coming precisely from those lands was immediately available in quantity and with ease.

The first uses of alum date back to ancient Egypt where it was used for the clarification of drinking water as well as  an additive in embalming processes

As for the use in our country we see that the word “Alumen” is already used by Pliny in the years around 77DC in his main work: the “Historia Naturalis”.

Pliny tells how the alum is found in nature and its use in dyeing fabrics, in the tanning of skins and for hemostatic and antiseptic uses.

The confirmation of what he described is also found in the discovery of “stocks” of Alum found in Pompeii in what was to be a “tannery”.

Only in 1460 in the mountains near Tolfa (north of Rome) was discovered the Alunite, from which, through a process of fusion, was obtained alum.

This was a decisive discovery as it sanctioned the interruption of the expensive supply of this product from the Middle East, which, until then, was the only place of extraction of this mineral.

This “national” source allowed that there were no shortages of this very important product even when, because of the conflicts between Venice and the Ottoman Empire the Mediterranean routes became impassable because dangerous.

Allume was for centuries a product of strategic importance and all major European countries needed it.

In England where the wool industry was of primary importance and therefore the colouring of the wool was a very demanding process, the great availability of this product was a real driving force to the industrial revolution. It was because of political differences with the Papal States (which in 1550 also owned the mines of Tolfa) that Great Britain took steps to find elsewhere this important product… Luckily, it was in Yorkshire that a concentration of rocks with a high alumina content (Shale Rocks) was found.

In order to exploit this reservoir, the “Alum works” of Ravenscar was formed. An industrial site on the Yorkshire Coast that remained operational until 1860 and that today is an interesting and visited site of “industrial archaeology”. It is certain that, with the support of the alum produced at Ravenscar, the development of the English textile industry assumed such a momentum that it became the catalyst of the industrial revolution.

… In the meantime, the fate of the Alunite mine in Tolfa was to pass to the Montecatini group at the end of the 1930s, before being definitively closed in 1941.

Today the production of alum in Italy is from chemical synthesis, and the product obtained, completely identical to the so-called “natural” enjoys the increased advantage of being cleaner and qualitatively homogeneous.