What you need:
-Yarn. All wool to mostly wool. Rather, mostly an animal fiber (wool, silk, hair...). Now your yarn can be a blend like 80% wool, 20% nylon. It just won't dye as vibrant. But the more wool/animal fiber content it has, the better. Cotton and acrylics will not dye! Don't even try it.
-Kool Aid or food coloring. Generally, you want one packet of Kool Aid per ounce of fiber. You can do more for a super bright, intense color or less for a softer, pastel shade. You want straight Kool Aid, not a mix with added sugar or sweetener (yuck! Sticky yarn!) VERY IMPORTANT: YOU DO NOT ADD SUGAR TO THIS. YOU JUST USE THE KOOL AID POWDER STRAIGHT FROM THE PACKET. With food coloring, I have no advice. You just play around until you find the right amount of dye for the shade you're looking for. You can use liquid food coloring or gel. Both work great! Make sure you're buying coloring and not colored flavored icing (with sugar).
-White vinegar if dyeing with food coloring.
-Gloves. Pretty much the most important thing here. Cheap rubber or latex gloves to prevent your fingers and hands being stained by Kool Aid.
-Tiny amount of acrylic yarn for tying off skein.
-A large bowl or sink. To soak yarn, to rinse yarn.
-A large stock pot to heat dye and yarn.
-A large plastic spoon to stir.
-Stove top burner.
A side note: Since Kool Aid and food coloring are non-toxic you can use your everyday kitchen supplies to do this. No need to buy "dye only" spoons, bowls and pots. Just wash them when you're done and they'll be fine.
So where do you get this dyeable yarn from anyway? I usually buy it online from Knit Picks. You can also find natural (undyed yarn) in craft stores and local yarn shops. Cascade 220 and Patons Classic Wool are great. You don't need white/natural yarn. If you dye over a tan, grey or any light color your dye result will look more jeweled tone instead of primary bright, bright, BRIGHT! Check this out to see what I mean.
Knit Picks Bare Peruvian Highland Wool in Worsted Weight. It's 200 yards/100 grams. 100 grams is about 3.5 ounces. So I'd need 3-4 packets of Kool Aid for a true color. I'm going with 3 for this dye job.
The yarn comes in a skein with two ends tied up. We want to add more two more ties on the other end. This will prevent tangling and make it much easier for us to handle after we've dyed it. I've used a small amount of red acrylic yarn and tied a loose figure 8 in the skein. You don't want it too tight or dye won't get under the ties. It doesn't matter what color, but acrylic yarn is great because the color doesn't bleed off (meaning, there won't be any red dye in my yarn.)
Fill your sink or large bowl with lukewarm water. Gently place yarn into the water and carefully press down and squeeze it. Try to get as much water into the yarn so it stops floating to the top. You're soaking the yarn so that when you dye it, the color absorbs more evenly.
Now if you're dyeing with food coloring, add a glug of white vinegar to this water soak before you add the yarn. Kool Aid has citric acid in it, which helps bond the dye to the yarn. Food coloring doesn't have it so adding a bit of vinegar will do the trick. Let the yarn sit in the water for 15-30 minutes. While this is happening, move to the next step.
Step Three (the fun part):
Get your gloves, Kool Aid and large plastic spoon ready. For today's dye job I'm using three packets of Lemon Lime Kool Aid.
Fill your large pot with water and heat it up on your stove. Dyeing with food coloring? Add another glug of white vinegar this pot of water. You want the water to be hot and steamy but without any boiling or simmering nonsense. I usually bring it up to temperature on medium heat and then take it down to low when it's nice and hot.
Put on your gloves (except I forgot. HA!) and pour your Kool Aid packets into the pot of hot water. Stir it with your plastic spoon until it's all dissolved. Food coloring dyers, you can squirt, drop and scoop your dye right into the the hot water and stir until dissolved. Not sure how much to add? Start light and you can always add more color later.
Now drain the water out of your yarn bath and gently squeeze the excess water out of your yarn. It doesn't have to be mostly dry, just get enough water out that it's not slopping around. Gently place the yarn into your pot of dye water. Use the plastic spoon to push the yarn down getting it completely submerged. Swirl it around, turn it over, loosen it up. Just be gentle so you don't accidently felt it. Add more hot water if you need. There should be plenty of room for the yarn to move around and be in water entirely. When dyeing, it's not the amount of water that is a concern, but rather the amount of dye.
How do you know when it's done dyeing? When it's the color you want or when it does this really cool, magical thing. All the dye that is in the water, goes into the yarn. So you'll know when it's done because the water is clear! Some Kool Aid flavors like lemonade will turn the water chalky white and not clear when it's done. But you're looking for the lack of color in the water to clue you in. Super cool right? This is why it's important to calculate the yarn to dye ratio rather than the yarn to water ratio.
Here's a photo of the yarn right when I put it in the bath. Notice the water? Super green!
And this is the pot of water after I've taken my dyed yarn out. No dye!
So when you're dyeing your yarn, stir it every couple of minutes to make sure it doesn't settle to the bottom (to prevent scorching) and to make sure all the fibers are getting dyed. When it's to the color that you want, or all the dye has been absorbed into the yarn (it took less than 10 minutes for this to happen), bring your large bowl over and use the spoon to carefully pull yarn out of pot and into the bowl. Let the yarn hang out in the bowl until it's room temperature. You may have gently flip or spread out the yarn occasionally to help the cooling process. Don't rush it! Be patient. We don't want to felt our yarn!
A side note: If it's not a deep enough color for you but the dye water is clear, pull the yarn out and put it in the bowl. Add more Kool Aid or food coloring and stir to dissolve. Add the yarn and repeat until color is achieved.
Woohoo! Dyed yarn! Once it's nice and cooled down, pull it out of your bowl or sink and put it somewhere for a second (dish rack? towel? plate?). Also, you'll notice how helpful adding extra ties to your yarn was. See how easy it was to untangle? Fill the bowl or sink with lukewarm water and put the yarn back in it. Swish it around. You're cleaning/rinsing the yarn. If any color comes off into this new water then STOP! Grab the yarn and put it back into the hot water in the pot and cook for a few minutes more- add another glug of white vinegar if using food coloring. If your water is clear, drain and squeeze the water out of yarn as best you can and hang to dry (nevermind my hula hoops). Here's my dyed yarn in it's rinsing bath. Water is clear! No run-off dye.
When it's completely dry, wind it into a ball and start knitting! Viola!! You did it! Now wasn't that easy?? Have you sniffed your yarn yet? Smells like candy!
Experiment with mixing colors. Dye one half of the skein one color, then dye the other half a second color. Look around. Be inspired by colors in your life! Dye and knit ALL THE THINGS! The Kool Aid dye is permanent. It won't wash off. Treat it like you would any other wool. Let me know if you have any questions in the comments below.