My other half having used this in a soap recipe and commenting on the yellow it turned, I had to try it on wool. I have a fair stock as this is one of my favourite drinks, when I remember that maybe I shouldn’t drink so much coffee.
Unfortunately I have been unable to get a photo of the true shades. I’m not very savvy with image manipulation, granted.
I’ve tried to zap up the greens a bit, as in the original photo they appeared very yellow, but have gone a little overboard. Maybe an indication of what they become? Or refraction at its most mirage-inducing?
Second down on the right – mordanted + bicarb modifier: this actually came out a lighter moss-green (i.e. not so limey) with brownish tones. It’s counterpart on the left, unmodified, is a pale grey-green. Bottom-left, unmordanted and unmodified is just grey, although a grey that you don’t find naturally in fibre, and on the right, a more greenish grey. Worth repeating? Definitely, for the greens and greys if required in a project.