Hot Box Natural Woad Dyeing

So, woad, what a fantastic quirky gift from Mother Nature...A leaf that yeilds a beautiful blue, but only if you hit upon the right alchemy...

This is my most recent method, involving that most maligned (because of the stink) of all waste products, WEE.
So first of all, fill a vessel with wee, let it sit, somewhere where it won't be disturbed or fiddled with for a least two weeks, until it stinks. You want the smell to make you gag when it gets you in the back of the throat. Then (if you're using powdered woad) add 2 teaspoons to approx 5 litres of gone off urine. With leaves, you just want to fill up your heatable vat (I use a big stainless steel pan) with as many leaves as you can and then pour the urine over them.
Then the method is the same: heat your vat with woad in to just slightly steaming point then PUT IT INTO YOUR PREPARED HOT BOX! This is the marvelous part of it for me, as I had to think it up myself!

I couldn't work out how I could keep my woad vat at a steady temperature, perhaps for several weeks, as I had no greenhouse, and our stove is never on constantly, as our house is too cosy, and doesn't need constant heating, even in the depths of winter. Then I remembered the hot box principle: Basically, heat whatever you need to keep at a constant temperature up to the temp you want it to be at, take it off the heat source, and then insulate it so that the heat stays in it. In my case, the most easily available insulation source was fleece (My house is literally full of the stuff). So I put a layer of it ( 2-3 inches)on the bottoms and sides of an old cardboard box, then placed the heated pots (in my case) with the woad urine vats in the hot box (see photo above) added a cosy wool covering to the pots, and shut the box up. I discovered that this will stay warm for approx 24 hrs, and then you just heat it up again to slightly steaming point, and put it back in the hot box again. Probably after 3-4 days the woad will have dispersed enough and the vats' oxygen reduced enough for you to begin dyeing. You should be able to tell because the vat will look greenish. If there is a blue scum floating on the surface you may need to add more gone off urine. I keep my wool fibre in for 24 hours to absorb the vat fully, and then I air it by pulling it carefully out of the vat on a stick and watching it magically turn blue in the Air! If it's too pale, I repeat the process and usually after 3 or 4 days it's a lovely mid blue. See above photo.
The important thing is too keep your vat at a steady temperature, although too cold is more easy to rescue than too hot, which can give you greys and maroons rather than the magical blue you are after.
I rinse my woad dyed wool in luke warm vinegar water to help it bond to the fibre. Then air it until I wash the smell fully out! The smell will always lingre a little, but generally only when the fibre is wet....
 You can top up your vat every few days with urine until the woad is worn out. If you have more woad, you can keep it going for weeks, but your family may not be impressed with the smell of you heating up the vat everyday on the stove.....