Susan Mousley Lecture: “Extracting and Dyeing with Indigo” with Dr Ian Bowers

Dr Ian Bowers. “Extracting and Dyeing with Indigo, the myths and pitfalls” Managing Director of George Weil & Sons

This talk is supported by a bequest from Susan Mousley, a former member of the Guild

Indigo as a colourant has a very long history.  There are a number of sources of the dyestuff in nature found across the world.  Extracting indigo pigment from plants requires a complex set of conditions to draw out the sap and then to turn it into an insoluble powder which can be stored and transported.  In many communities with absolutely no knowledge of chemistry, complex rituals generally, but not always, work.  In others the procedures have now become miniature industries requiring many stages and many people to create the product.

Indigo powder is unlike all other colourants.  It is completely insoluble in water and requires two distinct processes to make it available to act as a dye.  The first stage involves creating a dye vat which takes away one part of the indigo structure and with this gone, what is left will react with another chemical in the dye vat to become soluble.  Fortunately, the new form of the indigo is desperate to return to the insoluble form and bind tightly to the surface of anything dipped into the vat when exposed to air.  Simple it may sound, but many things can go wrong and an understanding of the ‘magic’ can bring regular success.