I participated in a local CSA program (community supported agriculture) which gives members a bag of fresh vegetables every week. One week the bag included fresh Turmeric grown in the hoop house. The turmeric root is bright yellow and usually used in curry and other similar dishes. I already had a container of good ground turmeric in my spice rack, so I decided to use the fresh stuff to dye yarn.
I started by cleaning the roots and chopping them into small pieces. The more surface area that is exposed, the easier it is to extract all the color available into the dye bath. I added the chopped pieces to a pot of water and simmered for an hour or so to extract the dye. (Note: I have a special pot set aside for dyeing, that is not used for food.) I noticed that the dye wasn't very strong, so I supplemented the chopped roots with a teaspoon of ground turmeric from the pantry.
Luckily turmeric does not require a separate mordant to dye effectively. Mordants prepare the fiber for dyeing so it can accept color from the dye bath. Certain natural dye stuffs have a natural mordanting agent, so the fiber does not need any pre-treatment. I took my ball of Paton's Classic Wool and wound it into a large loop so it could move freely in the dye bath. After securing the loop, I soaked it in cool water in the sink to remove any bubbles or air pockets from the fiber (this helps the yarn dye more evenly.)
I turned the stove down and added my fiber to the dye pot so it could simmer for an hour or more. I also added some wool roving to the dye pot, so I could use it for spinning later. As an experiment I dipped one section of roving into an acidic solution (vinegar) after the dyeing process, and one section in an alkaline solution (baking soda and water.) Treating dyes fibers in different pH solutions will change the color. One section of roving turned brighter yellow and the other turned a little redder, and shifted towards orange.
Apparently I fail at documenting my process in photos... Because this is all I've got. Don't worry, I've done a lot more dyeing since then and I (sort of) got better about taking photos. Stay tuned for more posts about natural dyeing!