I have oodles of wool yarn that I love felting with, but it is light in color, sort of winter white or very light cream. I dye with RIT, Tintex, couple of Sabraset colours, Kool-Aid, coffee, and have experimented with other staining mediums. I want to share this successful experiment with you:
Rit and Tintex darker colours results lousy. Black turns out more of a sickly purplish-blue, or light grey if you are lucky and don't have a heavy hand when adding the dye. Someone wanted a dark pair of felted slippers, which got my thinking gears working. I bought a bottle of India ink. I liberally sprinkled the RIT to the water, then added a couple of droppers-full of ink, and added a splash of vinegar to the mix. (Apple cider vinegar actually, as that was all I had on hand.) The result was a dark charcoal grey, which held up fairly well during felting in the washing machine. There was a bit of bleeding, but the end result was basically the same colour as when I removed the slippers from the dye bath. The India ink definitely added darkness to the colour that I would have otherwise achieved with only the dye. Now I am wondering if I could achieve a jet black by using more India ink, or by eliminating the Rit altogether and liberally adding the India ink??? That will have to be an experiment for another day.