Blues: WoAd and Indigo
Woad and indigo have the same dye chemical in them. The indigo has a higher content and therefore it requires less dye stuff to dye. That being said, I will take woad over indigo any day. Woad is less intense and I find it easier to get the shades I want. I also find it's also easier to rinse out the excess woad. I know dyers will argue with me, but that's my personal experience. But, the best reason? I can grow woad in Canada! I've written up a description of my adventures in growing my own woad, that you can find here -Woad extraction
Dyeing with woad and indigo is a lot different than the yellows. It requires more chemicals and equipment, more time, and a high tolerance for stink. I use the method described by Maiwa.
I find the Maiwa directions very straight forward so I won't repeat them here. The link above takes you to their publication on how to reduce a vat. The methods for indigo and woad are the same, only quantities vary.
I will advise a few things:
Read ALL of the directions before starting. Timing is important... so is having all of the chemicals and tools you need.
You'll need to use lye and thiox, so rubber gloves are essential!
You will need a large "vat." I use a 30L stock pot. Sixty would probably be better but I can barely lift the 30L half full!
Make sure your fibre has been soaking in water and is thoroughly wet before putting it in the vat. It ensures the indogin can penetrate all of the fibre.
Although not strictly-speaking necessary to mordant fibre before dyeing with woad, it is advisable. It is also necessary to mordant if you plan to overdye with another colour.
It will smell like a sewer. Do it somewhere well ventilated... and don't invite your inlaws for supper that day.
To get darker colours, you have to remove the fibre from the vat, let it oxidize, and then put it back into the vat, repeating this process several times. A thorough oxidation between dips is important, and sometimes, depending on the amount of fibre you're using, you'll have to reduce more woad/indigo to replenish the vat.
The difference between the first dip (left) and three dips (right)