A&S 50 - 3: Learn to dye with Indigo, modern method

 Indigo is unique in the universe of dyes in that it requires no mordant to produce a clear, lightfast blue on any natural fiber. True indigo was known in the Roman world, but remained rare in Europe during the middle ages until the 15th century. A chemically identical dye can be extracted at much lower concentrations from woad, which is much harder for the modern reenactor to obtain but was easily obtainable in medieval Europe and a major source of dyestuffs throughout the period.

Indigo vat prior to complete reduction

Regardless of which plant provides the material, the dyestuff is reduced through either a fermentation process or the use of chemicals to make it soluble. The dye solution then changes from deep blue to a milky yellow color. This “white indigo” can then be used in an alkaline dye bath to dye fibers. Once the fibers have been removed from the bath, they change from yellowish-green to deep blue as they react with the oxygen in the air.

Linen just after removal from the vat.  Note the color

In period, the indigo would have been reduced using either urine or fermented bran-water. Both of these processes can take up to a week and produce very offensive smells, so in the in interest of time and my marriage I elected to use modern methods for my first attempts. I began by using a yeast vat to reduce the indigo. In theory, this works the same way as a fermented bran-water vat; the gases produced by the bacteria reduce the yeast and drive suspended oxygen bubbles out of the dye liquid. However, I was unable to keep the vat at a constant temperature to complete the process long enough to reduce the indigo using this method and, after more than 24 hours, opted to use color run remover to reduce the indigo.

Once the vat was reduced, the actual dying process was relatively straightforward and quite satisfying. One must take care not to introduce air into the vat, so the fibers cannot be stirred or agitated much once they have been placed into the dye. This can lead to somewhat uneven absorption of the dye, but washing the fibers thoroughly prior to dying and adding them to the dye pot wet seemed to help mitigate this. A second dip in the dye pot resolved most of the splotchyness which occurred only on the linen skeins. The wool dyed evenly without any stirring at all.

Complete wool and linen skein drying

Sources:

Dean, Jenny. Wild Color. Watson-Guptill Publications, 1999.

Bingham, Gayle. Woad Dying. Medieval Textiles issue 29. Sept. 2001. (http://www.elizabethancostume.net/dyes/medtex.pdf) Last visited Nov. 18, 2010

Kolander, Cheryl. Dying with Indigo – Natural Fermentation Vat. (http://www.aurorasilk.com/info/indigo_tutorial.shtml) Last visited Nov. 18, 2010.

Priest-Dorman, Carolyn. Colors, Dyestuffs, and Mordants of the Viking Age: An Introduction (http://www.cs.vassar.edu/~capriest/vikdyes.html) Last visited Nov. 18, 2010.