I thought I'd check in and give you an update on my search for a dye recipe for gray. I've approached it on 2 fronts.
First I'm using Dharma's other blacks and trying to mix other colors with them to make them closer to real black and gray. For all of my samples I am mixing a color at 50% strength so I can see the gray. Black is reasonably easy to do. It's the shades of gray where the real color comes out. You can see that the sample on the left is getting closer but it's still way too green.
These samples are all created straight from my own recipes. I started (on the right) with my recipes that were closest to black but they were still pretty brown. The one with the arrow is the one that I'm going to be working off of next.
I do 3 - 6 samples each week and I know I have weeks and weeks of work still ahead of me.
I've also been making red. I think I've made about 25 new red recipes in the past month. I'm on a search for a red that's in my mind......the perfect red for my next palette.