After watching some YouTube videos, I was finally ready to dye yarn with a longer colour way, than you can get by dyeing it in one skein. I first split it into about a dozen connected mini-skeins, then soaked my 100% fingering wool overnight in water, with a splash of vinegar.
In the morning, I selected several colours and mixed acid dye powders into hot water with a dropper of vinegar.
The colours ranged from a grey blue to red with yellow, green and brown in the middle. I generously applied the concentrated dye liquid to the yarn, that I had laid on plastic wrap on my table. I carefully wrapped the skeins, avoiding contact, laid them on my glass dish and microwaved them for several minutes, a minute at a time.
The resulting yarn was bright! After crocheting a one-skein shawlette with my bright rainbow yarn, I over-dyed it in a blue dye bath. Now it is a little dull for my taste, but dyeing the yarn in small skeins was a fun experience.