Prussian blue

The significance of Prussian blue lies in the fact that it was one of the first modern pigments to be synthesised. This took place in Berlin in or around 1704¹ and was a matter of pure alchemy — and serendipity.

Johann J. Diesbach (1670-1748), a dyer and colour maker, wanted to prepare Florentine lake, a cochineal-based red pigment, for which he needed a fixed alkali with which to mix iron vitriol, among other ingredients.

He asked the well-known alchemist Johann Konrad Dippel (1673-1734) to provide him with some of the waste material from his work — a quantity of potash, which in Dippel’s laboratory it so happened to be a waste from the production of his oil (Dippel’s oil, an oil derived from bones and animal matter).

Diesbach prepared everything as usual, but the following morning, instead of the expected red pigment, he found a beautiful blue one.

He mentioned this to Dippel, who realised that the unexpected colour was due to the reaction between the particular potash and the iron vitriol. The oil on which he had been working had been prepared using animal blood, and the reaction of its waste products with the iron vitriol had produced this new colour².

The pigment was being produced industrially within a few years³.

Since its synthesis had been achieved in Berlin, in the Kingdom of Prussia, it subsequently became known as Berlin Blue or, more commonly, Prussian Blue⁴.