Then I stumbled upon a site that outlined how to use vinegar and food dye to color your yarn, with the same result, without the harmful drawbacks - and it's a frugal alternative to buying single acid dyes that cost 5 dollars or more a piece. I had me a spare skein of bare yarn lying around, and I decided it was time to try this out.
1. A skein of bare yarn, be it alpaca, merino, or wool. (I used 100% wool, from Knit Picks)
2. A clean sink (Time to get those dishes done!)
3. At least 2 cups of vinegar.
4. A set of food coloring. (Mine were McCormick)
5. A working crockpot. Because it's food coloring, you will not ruin it!
The Night Before:
Note: The crockpot isn't on during this step, I just didn't want to dirty two dishes unnecessarily, and when we do "cook" the yarn, it'll be in this dish anyway.
For starters, I grabbed my crockpot, poured 3/4ths cup of vinegar in, and then added some water. After getting my yarn settled in this bath, I added enough water to just cover my yarn, popped the top on, and walked away. You'll want to let this sit overnight, if you really want your yarn to absorb your colors. If you don't want your yarn so bright, you don't need to do this soak. I did end up checking on it later on, and added more water as the yarn had absorbed some.
The science here is, really simply, the vinegar is an acid that works to open up all the crazy little fibers in our sheep hair, so that when the color and heat are introduced, all the color can be soaked up. Without the acid, your yarn won't absorb the color, and you'll be the new owner of a skein of off white, or oddly brown yarn.
The Next Day:
In a nice clean sink, drain the water off and gently rinse out the yarn. Don't go too crazy here, just give it a quick run under the tap, I did this when it was still in the crockpot bowl. Refill the water so that it's just covering the yarn, you can add more, so that your dyes float around more and mix more, but that's up to you. Then add 1/2 cup of vinegar.
Pop it back into crockpot heating mechanism, put it on high, and wait until the water is hot enough to steam. Roughly 2 hours, depending on your crockpot. Do your nails, take the trash out, or whatever it is that makes you happy. (Knit, perhaps?)
Near the tail end of the heating process, it's time to make your dyes! If you are using gel, or any food coloring that isn't liquid then you absolutely have to dissolve it in boiling water. I used liquid food coloring, so I didn't have to worry about that.
I used a 1/2 cup of water to dilute each color in. I made them pretty dark, but once added to the pot
and the water therein, they lightened up. I'm sure there's an art to this sort of thing - but don't look at me for the secrets, I haven't figured it out yet. Then I did what other dyers would probably say is a bad thing, a very bad thing indeed, but I skip to the beat of my own drum, dammit - I grabbed my spoon, lightly held sections of my yarn down, and added a few drops of color here and there. Right from the bottle. I swished the spoon around some, and then finally walked away when I was happy with the witches' brew before me.
Now your yarn sits. It's out of your hands. My yarn sat for about an hour to an hour and a half before it had soaked up all the color. My water was 100% clear, seriously, your water should look like this. (Which is actually what my water looked like after the yarn was removed for rinsing.) If it doesn't, the yarn has not absorbed all the color it can.
I was pretty satisfied with my first yarn dyeing, so I turned off the crockpot, and let the yarn alone until the water was room temperature again. I really don't recommend getting hasty and skipping this step, you're using an animal fiber here, and the chances of felting all this beautiful newly crafted yarn is just too high. Now, if the coloring wasn't exactly what you were expecting, it's fine to add more coloring and then let it sit until the water is clear again.
Once the water your yarn is setting in is room temperature, it's time to give it a rinse. I dabbed some baby shampoo in my hand, got it nice and bubbly and very lightly washed the yarn out in cold water. Rinse it out real nice like.
I then threw it in a lingerie bag, and put it through the spin cycle in my washer (which is a top loader). This step isn't necessary, I just wanted to get as much water as possible out. If you don't have a lingerie bag, and don't want a tangled mess of yarn, just wring it out as best and lightly as possible.
Then it's time to hang it up as best possible, as I did, to dry. I tried to have it drape across two hangers, for even drying. My final color was a little more pastel-y than I had anticipated, so next time I will definitely be going heavier with the food coloring added, but I'm still pretty pleased with what I got. I even have the perfect project.