So I finally dyed some yarn with my sorta new black dye, following the instructions. The first two skeins will come out okay, I think, though I'm not entirely sure about the green.
I had some dye left over, so I dyed up a skein of superwash merino that I hadn't used before. This one was a bit of a disaster--the dye did not penetrate evenly, so I had to basically paint individual strands, but I didn't have enough room because of the other two skeins that were still curing in my work space, so the dye job probably wasn't very tidy. And the black dye, which was basically a slurry, got smeared in places where it wasn't supposed to be. Guess this one will be a tester skein for me.