For long I have put off trying out indigo, as a natural dye for cloth and wool. There are some classic traditions - batik and Shibori come to mind. And of course the legions of denim jeans through the decades.
I have had a sense of a mystique surrounding indigo. This was demystified a few days ago when I joined others in my art quilt community - Contemporary Quilt and Fiber Artists - for an afternoon with indigo dye pots. What fun!
It was a very straightforward process. There are a couple of key things specific to indigo dye, different from either procion or other natural dyes.
The oxidation factor means that it is important NOT to introduce air/oxygen into the vat, as it depletes the dye bath more quickly. So no splashes, bubbles, agitation. Just a slow even dip and recover from the vat of things being dyed.
Another emphasized instruction was to fan folded items, as the indigo rests on the surface of the fiber. Yes it wicks, but not as easily as other dyes. By fanning I mean, gently pull back the folds, to help both the dye enter AND more significantly to let the air reach the dye, as the oxidation is key to the color change and cure process.
The third key learning is that indigo benefits from curing. It is better to hold off a few days to wash or rinse what you have dyed.
I worked with wool that I had spun, as well as fabric samples.
This one is a Romney 2 ply, natural light brown.
A skein dyed yellow with oxalis some time ago, then overdyed
Coopworth fleece, 2 ply spun. Classic gradation.
Same wool, solid.
Silk - randomly crumpled and clipped with clothes pins, binder clips, etc.
Commercial print cotton
Another, but one that was originally printed in the indigo color range