My signature for many of my weavings is hand-dyed yarn. Playing with colors is my favourite thing about making cloth and it is so deceptively simple to create a kaleidoscope, creating movement and interest in the weaving warp yarns.
I order all my dyes from ProChemical in the States. I have only ever had a couple problems with the dyes, some colors, such as brown, will not take no matter what I do. Most of the other colors are great. I am still on the valiant search for the perfect red dye that will not wash out as fuschia or blank pink.
After winding a light coloured warp, I tie a bunch of loose choke ties to keep the warp from tangling in the pot. The warp then gets soaked in a pre-mixed soda ash solution. I have been dyeing cotton for long enough that I don't measure soda ash anymore, just close my eyes and pour till it feels about right. The soda ash FIXES the dye to the cotton, there will be no bright colours without it. After donning latex gloves, I squish and press the warp into the soda ash water until it is totally soaked and saturated. Some mercerized cotton yarns are infuriatingly water resistant so this step can take awhile, but it is very important for thorough dyeing. I have heard of pre-washing yarns in a detergent but I like to skip that step.
After the yarn is nicely squished and soaking in the pot, I dump out the excess soda water so the warp is still soaking wet but not floating in water. Then the fun part begins. I sprinkle dyes on the warp somewhat haphazardly. The power just goes right into the pot. I usually flip the whole mess over a couple times and use my highly sophisticated plastic utensils to sprinkle the dye powders and work them into the yarn. Once there is enough dye has been worked into the warp, I force myself to forget about it completely for 8-12 hours. I've made the mistake a few times of prematurely washing out the dyes or messing around with it out of curiosity, but I find the best results are had with patience.
After dyeing, the warp gets rinsed. There is a fine line between needlessly tangling the warp by over rinsing, and not rinsing enough. I tend to err on the side of not rinsing enough and walk around with coloured hands for a few days after dressing the loom.
I wanted this particular warp to have subtle colours to match the accent beige yarns I had planned for the warp. That's fairly easy to obtain by reducing the amount of soda ash used before dyeing. For really brilliant colours, I use a shorter warp with lots of fixer. Trying to get brighter colors by adding more dye powder tends to create muddiness and for some reason, all the colours blend together to become purple! One of my least favourite colours next to pink. :)
I used to try recording how I placed the warp in the pot and how I distributed the dyes over it, as if I could ever duplicate it again. I have tried and tried and tried to duplicate a particular warp that I dyed about 5 years ago and it has proven to be impossible. Rather than bash heads against the wall, I'm now content to accept all my weavings as unduplicat-able and I have found that omnipotent imagination never runs out of ideas.