This post is more a memory aid for myself, so I don't have to google it yet again. I've previously looked it up & failed to write it anywhere.
I've got some pale pink linen/rayon herringbone fabric that I want to make a summer skirt from. However pale pink doesn't actually suit me. I got it as it's going to be easy to dye a darker plum or wine or berry colour that does suit me. It's going to be more random colour than specific, and I'll use iDye for natural fabrics. Mainly cos it's easy to get, and the other dye I could get from ebay says it needs to be used with soda ash, but (i) they don't sell that also and (ii) I can't seem to find anyone who does, or who says what it's also known as.
So my recipe is 1 violet and 0.5 black.