Woad from Scratch
Woad is biennial but fortunately, it's the first leaves that have indogin in them, so you don't have to wait long for harvest.
Woad is an invasive weed, so be careful where you plant it!
See this bathtub full of second year leaves? THAT was a lot of work for NO DYE!! However, those second year plants will give you piles of seed! I haven't had to buy seed for five years. The seeds also seem to be viable a couple years later.
The first year woad plant looks a lot like a dandelion. Its leaves are more rounded, rather than toothed, but it isn't easy, when they're young, to tell them apart.
It takes around a kilogram of woad leaves to get approximately one gram of woad dye. That's a lot of plants!
To extract the dye from the plants, I used the technique described by Teresinha Robert (Woad Extraction).
The leaves were steeped at 80C for 30 minutes. This gave me a brown liquid. They were then cooled by putting the pot in a sink of ice water. Once cool, I strained the leaves out of the liquid with a plastic collander
After adding soda ash to reduce the liquid, it darkened.
I "aerated" the liquid by pouring the liquid back and forth between two pots. It was back-breaking work!
This is done to oxidize the indogin, making it come out of solution. This produced a froth as the soda ash became agitated.
In the bottom of the pot, sediment of the dye stuff eventually started to precipitate!
Once the liquid was aerated, I left it to settle. I then poured the top half off, and let it settle some more.
Once it was settled, I poured it into glass bottles and let it settle some more.
Everyday for a week I used a turkey baster to draw off the top half of the liquid, leaving the sediment in the bottom of the jars, and then refilling them with water. Eventually the water was clear and the sediment was ready to be filtered.
Unfortunately, woad extract is incredibly fine. Even using 8mm habotai silk, some of the dye passed through. Because the silk is so fine, it took forever for the water to pass through once the woad started to get caught.
Also, the woad is fine enough that you lose some in the fibre of the silk. I think, in future, I will draw off enough water than I can let the water evaporated off.
Next step? Woad balls!