There are different types of yarn dyeing, and about four years ago I chose to start with the "natural" method. I fell in love with it so much, that I never tried anything else.
Here are the basics of Natural Dyeing
1. Fiber Selection
We choose to dye only protein fibers, mainly wool. Protein fibers take up dye much easier than plant fibers (such as cotton) and we find them more enjoyable to work with. Superwashed fibers and wool blends can be dyed, as long as about 75% of the fiber is protein.
All fibers that are going to be dyed need a mordant (French "mordre", which means to bite) in order for the color to fix to the fiber. We use only Alum, a metallic salt traditionally mined as a ground mineral. This is usually done by heating up a large vat of the fiber and mordant to 180 degrees and maintaining this temperature for at least 45 minutes. To save on resources and energy, we "cold mordant" our fibers for 5-7 days. After the fiber is mordanted, it can be dried and saved until use or immediately dyed.
3. Natural Dyes
Natural Dyeing means using plants and insects to obtain color. The ingredients are much more expensive than synthetic dyes, but natural things usually are. Many dyes come in concentrated extracts or even liquids, although we also use whole dyestuff (cut flowers, plant roots, etc.) and plants that we are able to find locally. Some of our favorites are Saxon Blue, Madder, Cochineal, Rabbitbrush, Weld, and Quebracho Rojo.
4. Dyeing Process
After the fibers are mordanted, they must be presoaked before dyeing for even coloring. The fiber is then submerged in a "dyebath" of the dye mixed in water. Some dyes "strike" the fiber fast, and not much heat if any is needed. Other colors need to get to a certain temperature before a particular color is achieved. Combining colors can produce even more color ranges, and everything is done at a percentage of the weight of the fiber.
5. Finishing and Drying
Our fibers are all washed, rinsed, and finished with a leave-in conditioner formulated especially for fiber dyeing. We do not rinse our fibers until the water runs clear necessarily, because we see that practice as wasteful when the ingredients of natural dyeing are natural, and color bleeding is sometimes almost impossible to avoid without ruining the fibers through exhaustive rinsing. Some colors inherently run more than others, and we do our best to minimize this with the most efficient yet environmentally conscious practices.
6. Variations in Color
Hand-dyeing in general produces variations in results, but natural dyeing is even more varied with the color results, even if a recipe is replicated exactly. The pH of tap water, temperature of the water to the degree, time in the dyebath, and movement of the fiber in the dyebath all impact the color results. But natural dyeing goes even further than these variables, to even the season that the dye was harvested. This means that two hanks dyed exactly the same way might yield somewhat different results. Natural dyeing is just ultimately not predictable like synthetic, but that is the reason we love it and continue to use this method. To enjoy naturally dyed fibers, the accepted color range must be more broad even for a carefully notated recipe.
Natural dyeing is a beautiful, inspiring and an incredible way to achieve color. It behaves with a personality, changing with certain variables and still surprises us after four years. Just like no two strawberries are the same, nor will two skeins.