Mordanting 101

Through a turn of events I had today off from my usual work, so I decided to go ahead and pre-mordant the merino yarn in preparation for Saturday’s cochineal adventure. This is harder than it sounds because during my research into the field of natural dyeing I discovered that there were hundreds of “perfect, never-fail” recipes—all of them slightly different and some even contradicting each other.

My conclusion is this: get over it and jump in. If there are so many ways to do it, and it works for all of those ways, there must be a pretty significant margin of error. I may not get the exact color I want, but I’ll most-likely wind up with something usable.

Now that that’s out of the way, let me explain what a mordant is. When you dye with natural dyes (bugs, plant juices, that sort of thing) you will need something to make the color permanent. Some dyes have this built in, but most plant juices need a little extra help. This is where (usually) natural dyeing becomes less natural and we bring on the chemicals. I’m using the “least toxic” mordants I can find. Alum Potassium (which comes in a white, powdery form and is sometimes used in chemical fertilizers) and its extra-special helper, Cream of Tartar. I don’t use the usual baking cream of tarter; I order it online in bulk. Well, “bulk” meaning a four-ounce jar. You can also use Tin, Chrome (very toxic!), and Copper . . . and there are a couple more that I can’t remember at the moment.

Anyhow, when you use a mordant, you somehow modify or change or re-group the molecular structure of something and it makes the color stick to the fiber and become “permanent.” You can either put the mordant and the dye in the same pot, then stick in the fiber, or you can cook the wool twice. Once in a pot with the mordant, and again in the pot of dye. I chose the latter method because it looked a little more controlled. I read about someone who tried to put the mordant in a cochineal bath, and the mordant stuck to the pigment but never grabbed the fiber. She wound up with nicely red water and a pale pink yarn. This is not really what I want to have happen. So, here I am mordanting.

If you can chill out about using potentially dangerous chemicals, it’s rather easy and enjoyable. First step, soak the yarn for at least a couple hours. Look at that! I broke the first rule and the day’s still young. I only soaked mine for one hour.

Then, using a rough recipe that I complied from two varying opinions, I used three and a half tablespoons of alum, and three-fourths of a tablespoon of cream of tartar (which I have seen referred to as “c.o.t.” or “cot,” so if you see that you’ll know what it means).

I filled my biggest pot with room-temp water and pulled out a mason jar for dissolving the chemicals. It works best if you dissolve them in boiling water, then add them to the room-temp. This keeps them from clumping together and sticking to the yarn, and if you bring the whole pot up to boiling so you can add the chemicals you run the risk of shocking the poor little skien into a felted state. Not good.

So, now I’m waiting for the yarn to come to a simmer so I can simmer it for an hour. At that point, theoretically, the alum will have left the water and bonded with the fiber, so I can drain and rinse the yarn and hang it up somewhere to wait until Saturday’s dye party!