On Friday 30th August I ripped the leaves up and covered with 3 litres of boiling water and left to stand
Two hours later I squeezed out the leaves and the liquid was a very dark tea colour and at pH 5.89.
I added 1 tablespoon of washing soda, the pH went to 9.18 and the liquid to a dirty slimy green.
After beating for 3-4minutes there was a faint blue scum on the surface
I added 1/2 tablespoon of washing soda and brought it up to 9.59. ( This was to replicate the vat I did with the students which was a rather high pH but worked)
The foam went a slight turquoise blue in a few places . But dear oh dear where was the deep blue foam I had expected. :(
I beat for another 2/3 minutes but there was no change to the foam
I added 1 teaspoon of Thiourea dioxide and put the plastic bowl inside another bowl to which I added hot water. The vat was a nice hand hot 50 degrees C.
I expected to find that this amount of fresh Isatis Indigotica would have dyed 100 g of wool much deeper blue. Leena had the most fantastic result with her persicaria (polygonum) Tinctoria the Japanese Dyer knotweed and I was hoping for something similar!
The dogs and I went off for a walk to think about this. Provided the dogs are well behaved this I find is a good thinking time. Then I had a light bulb moment when I remembered that Enys and her DH only manure and dig over the bits where the vegetable are grown and don't feed the areas where the dye plants and the the herbs grow. I know they have not been watered with a nitrogen feed which mine have and I felt that one of the reason for the weak vat was the fact that the plants had not been fed., woad ( isatis Tinctoria)was/is notorious for needing rich well manured soil and I assume the chinese variety would be the same. I also think that the pH was too high for wool. I find that wood dyes best at pH 8.5-9 and at a hand hot temperature.
Here is another experiment . Remember? Back in the days , at the beginning of July ,when we thought we might have a sunny summer I put this out in my sunny spot.
The tannin bearing plants which with iron quite quickly went black. The fibres on the top of the jar went black ( well until I washed them but the bottom ones stayed white). Here is the result.
Might have been better with the sun on the jar!