This is powdered extract of fresh leaves of Isatis tinctoria, also called woad (/ˈwoʊd/), dyer's woad, or Jerusalem Asp. In France it is called pastel and in German Waid. In Dutch we call it wede.
Woad is a flowering plant in the family Brassicaceae, a biennal herb up to 1.60 meter tall. Woad is also the name of a blue dye produced from the leaves of the plant.
Woad contains the indican, Isatan A and Isatan B, all precursors of indigotin. It also contains some Indirubin. You have to make a woad vat in order to use this powder, and you can combine woad with indigo. In the past, woad was formed into woad balls that would cause fermentation to take place, thus forming the indigotin needed to dye blue. Nowadays woad extract is produced by alkaline hydrolisation just like regular indigo powder.
For the samples I created a simple hydros vat using the instructions of this blog with 10 grams of woad powder per liter water, you can use 5 grams per liter for a medium shade of blue. From experience, woad extract needs less hydrosulfite than a regular indigo vat.
I have written an extensive blog about indigotin extraction that you can read here.
The Sussex Soap Company made a beautiful soap using our Woad powder, you can watch the instructional video here.
Reviews
I used this woad in my soap recipes after I had to reformulate all my recipes containing indigo after that got banned for use in soap in the UK. It works beautifully and is also appropriate as woad was used a lot in Celtic Britain.
I love this Paler Shade Of Blue. I dyed cotton, linen, silk and wool. I used Suzanne’s recipe for a strong vat, 25 grams. It went a long way. In the end I threw in a white Terry hand towel to exhaust the dye vat. Eventually, when I have enough yarn dyed I will weave a silk shawl and a
wool scarf.