Amy and I will be blogging about our experiences with the Kool-Aid dye next week. I'm just a beginner, this was my first time dyeing. Nina has done a lot of food color and Kool-Aid dyeing, she might have some ideas for you.
I tried dipping different sections of the blank in different pots of boiling Kool-Aid. I also thought about dripping it on the blank with squirt bottles or painting it on with a brush, but I didn't try it, so I'm not sure how it would work out. I've just seen people in the office use those techniques with the acid dyes.
There are a lot of fun ways to get color variation on a sock blank! You can "paint" right on it: soak the blank in a solution of water and white vinegar or citric acid, wring it out and lay it flat. Then paint it with your premixed dyes (any dye in liquid form will work, so kool aid, jaquard dyes, food color drops in water, etc), either from squeeze bottles (like the ones used to dye hair!) or with those foam brushes from the hardware store. Once the blank is painted, roll it up in plastic wrap and pop it in the microwave for a couple of minutes, or put it in a steamer on the stove to set the dye. let it cool, and then rinse, and you're ready to go!
If you want a long color transition from one end of the blank to the other, then you'll want to immerse the whole blank into a dye pot and then pull it out an inch at a time in 5-minute intervals, adding more dye to the pot as you do. This way, one end of the blank will be light and the other will be dark.
There are a lot of cool methods for dyeing in this knitty article:
I've used my own handspun yarns--mostly fine cross-bred from Australia. I pick whatever dyestuff that looks good in the garden, soak it. I mordant the skeins of yarn in one of the 5 mordants, let soak and dry. Then add to the dyepot in which I've boiled the dyestuff at least an hour. They simmer an hour or two, let cool in the pot, hang dry, then wash to remove the leaves, twigs and excess dye (usually none left in the fibers). I then shock the yarn before knitting or weaving with it so that it will never shrink--dry and have fun!! My dyed fabrics and sweaters have been in use for 38 years and have not faded, are soft and smell good!! The "natural" dyes are naturally grayed down, therefore shades of the various hues and combine with each other extremely well. I've done limited chemical dyeing with wool using acid dyes--experimented getting an entire 32 color wheel mixed and dyed from the 3 primaries--one learns a lot about color when hand dyeing. I taught some dye methods including indigo from "scratch"--great fun watching it bloom!!