O.K. I tried overdyeing my yarn with red food dye, it came out a dark burgundy red. Not ugly or anything, just not what I was looking for... I then tried the blue food dye... Oh, that produced very interesting results! That's what I chose!!!
Here are a few examples of my experimentations, starting from the left:
The original color, first red bath, second red bath, red over dyed yarn dunked in a blue bath, first blue bath, second blue bath.
The February Lady Sweater is now soaking in a blue bath corresponding to my favorite result, the first blue bath... Here's how I did it:
After soaking the sweater in warm water, I poured two 28ml bottles of blue food dye in a big pot, also full of warm water. I stirred the dye in the water, then I lowered my sweater in the mix. I heated the water to the almost boiling point (to where a bit of steam was coming out of the pot), after 10 minutes, I added a splash of white vinegar to the mix (it helps the wool absorb the color) , then I let everything steep until the water turned clear. The wool had absorbed it all!
The pot went on the counter to cool naturally. When the water was almost cool, I rinsed the sweater thoroughly.
Here it is drying slowly:
Remember what it used to look like? Blah...
Isn't this much better?