Most of what I dye/sell is hand painted with natural dyes. I know when I was learning, most of the info available was only in books, not websites, so I thought I'd write up an article on how I do it. Part one is all about mordants. Mordant comes from "mordere", which means "to bite". A mordant is necessary with most dyes to allow them to chemically bond to the fiber. Otherwise, the dye molecules just lie on top of the fiber molecules, and will rinse off. The mordant chemically prepares and opens up the fiber to bond with the dye. It's like the peanut butter between two pieces of bread.
1- Vinegar is a mordant. Vinegar is a pH modifier, NOT a mordant. Some dyes require certain pH to strike, such as acid dyes, and even some natural dyes do best in an acid environment. Plus, weak acetic acid like vinegar will help keep your wool from degrading. The acid helps "open up" some fibers, making them more receptive to mordanting and dyeing. It will, however, completely kill off, or "make fugitive" a lot of natural dyes if overused. You can also use vinegar and ammonia to change the colors you get from some pH reactive dyes. Do please be aware that just because the dye itself changed color, that doesn't mean that it will look any different once set on the fiber. Acid makes pinker, Alkali makes bluer.
2- Mordants for natural dyeing are very toxic. Maybe not so much a myth as an exaggeration. Yes, the metal salts used as mordants are toxic in their concentrated, powdered form. No, you do NOT want to breathe in the dust, or allow your children or pets near them. Common sense, people, wear gloves and a mask!! That said, the concentrations in which they are used are not nearly so bad. For a pound of fiber, you're going to want to dilute around only 1/2 an OUNCE of mordant (with the exception of alum, which you're going to need around 1-2 ounces. But Alum isn't toxic to begin with, so there!!) Once the mordant bath is expended, it is pretty harmless.
3- More is better. More mordant does NOT mean better color, it means destroyed fiber. Using too much mordant weakens and makes brittle your fibers. In some cases, it even makes them slimy. EWWWWWWW. Not so good.
4- Mordants are hard to use/too much trouble. Mordants take only a little bit of time to use, and without them, your natural dyeing is doomed to failure. You can even mordant by dissolving your mordant in water and leaving the fiber and mordant in the sun for a day or so while you let your dyestuff soak. Playing around with mordants opens up your range of available colors and techniques dramatically
There are a few commonly used mordants, and some less commonly used ones. The most common are:
Alum (Aluminum Potassium Sulfate): Pretty much, alum is the easiest to find and use, it is less toxic, and it gives what we will call the "base" color. It doesn't change the base color of your fiber. You can find alum, made by McCormick, in the canning or spice section at most grocery stores. You don't need a lot of it, and you can easily solar mordant with it. You want to dissolve your alum in lots of hot water, put it in your chosen vessel (pot, crockpot, solar dyeing oven, whatever, we'll discuss it later), put in your fiber, and that is it.
Copper (Copper Sulfate): Copper will turn your fiber a light aqua-to-greenish color. It is neat even by itself as a color. It can be used with yellows to get soft greens, to make blues and greens more turquoise, and to make "sadder" warm tones. Sometimes referred to in medieval recipes as "flowers of copper".
Iron (Ferrous Sulfate): Ehhhhh, some people class this as a "color modifier" not a true mordant. Makes stuff greyer/darker. Used with indigo or logwood, or even sometimes walnut, to get black. Known in medieval dyeing recipes as "copperas", SO DON'T ASSUME COPPERAS MEANS COPPER. You can pre-mordant with this like you normally would, but a lot of folks just use it after dyeing to grey it up. Used alone, iron will darken your fiber. I don't ever use it by itself as a pre-mordant. I only use it with something else, or afterwards to modify.
And some less common, but still widely used ones are:
Chrome (Potassium Dichromate): *TOXIC* This mordant is one of my faves. I ONLY solar mordant with this one, and never let it in the house. Chrome by itself turns the fiber yellow. It will make your colors richer in tone, and gives them a kind of antique-y look. I.E.-the pinks and lilacs from cochineal and logwood on tin become purple and dark blue. Here's some sock yarn dyed with those, done with the oven method.
Tin (Stannous Chloride): Brightens colors. Tin does not change the base color of your fiber. Tin will give you the brightest, clearest reds/yellows/oranges, and can be used with cochineal to give hot pink. It's my most favoritest mordant ever because I like the bright shinies, and it turns the mordant bath opalescent. Oooooohhhhh, pretty. Here's the same kind of yarn, dyed with the oven method in the same pan, at the same time, but mordanted with tin
What is pink here was the purple on the other, and what is purple here was the blue on the other.
Tannins: There are various sources of tannins, the most widely used one being Tara Powder. Tanins are usually used with cellulose fiber, not protein. Since cellulose fibers are harder to dye, in addition to the mordant, tannins help the dye bond to the fiber. They can be added in to your regular mordant bath when dyeing plant fibers, or done as a separate step if you're going to have wool in the mordant bath. Tannins can darken your fiber. Alum-Tannin-Alum is the best way to mordant on linens. Yes, it's three separate steps, but linen is a pain to dye otherwise.
I buy most of my mordants from chemical supply places on eBay. Do a search (description included), for the chemical name of the one you want....
HOW TO MORDANT
Allow me to suggest that you have dedicated mordanting vessels, and that you work outside. Most of the natural dyes, I'm not terribly concerned about letting in the kitchen, especially since a great many of them are herbs and spices that are already in my kitchen. I won't mordant in the kitchen, though.
The basic method is this:
Dissolve your mordant in a pot of warm water, LOTS of water (you need to let your fiber have plenty of space to move around, or the mordant can't attach everywhere), set it on the burner, and add fiber. Let it mordant for around 1/2 an hour on medium heat, then remove the fiber and RINSE RINSE RINSE. Remember, the mordant makes a chemical change, so rinsing won't hurt it, but too much mordant will. Having excess mordant in your dye bath can also give you less than stellar results, especially if you're trying to use different mordants at the same time. Excess molecules of mordant will float around and reattach in odd places, and in general play heck with your attempts to get even coloration, so RINSE.
You can also do solar mordanting. You want a vessel that is fairly flat, reflective inside dark outside helps too. Mix up your mordant solution, put your fiber in the vessel, and cover with mordant solution. Cover the whole shebang with plastic wrap and leave it alone for a few hours to a few days, depending on how hot and sunny it is. There are some great existing tutorials on solar dyeing on the web that discuss how long to leave fiber. After it's "done", rinse out your fiber. This is the method I use for BIG batches and anything chrome.
I have mordanting crockpots. I plug them in in the shed, leave them alone for half an hour, and then I'm good to start. You have to let the water get good and hot BEFORE you add fiber, and then leave it on the high setting for 1/2 an hour, just like on the stove. I have one crockpot for each mordant, picked up for $3 each at the thrift store. Remember to rinse, and rinse out your crockpots well so you don't end up with deposits of metal salts. This can make the crockpot explode. I had a crockpot that got metal salt deposits, and the next time I used it, it got a crack along the deposit line, and the metallic liquid got into the base and then the whole ceramic part shattered. Kind of neat to explode a crockpot, but nonetheless, a bad idea.
TRIPLE THREAT MORDANTING
This is one of my absolute favorites. Basically, you take your fiber or hank of yarn, and have it dunked into three separate mordants at once. I use the smaller size Ball jars and my dyeing microwave. I put the ball jars with mordant bath in the microwave on the turntable. Then I take slightly damp fiber in a skein (with roving I wind it into a skein around my elbow and use as is, with yarn I usually double the skein first), and stick one end of the skein in one jar, then the next section into the next jar, then the rest of the skein into the third jar. Stick it in the microwave for about three minutes, let it rest, another three minutes in the microwave, rest, and another three. The neat thing is, capillary action makes the mordants creep up the yarn, so they'll mix in the places that aren't actually submerged in any jar. The reason to do this is that then you can vat dye and get a subtly hand-painted, shaded look. In some cases, the difference is drastic, in some, not so much.
You can see the pinkish violet, the dull purple, and the blueviolet sections on this one, even after it was re-skeined.
Concurrent mordanting will give you somewhat unpredictable results, so even if you're really pressed for time I wouldn't recommend it. In concurrent mordanting, you add the mordant to the dye bath, toss in the fiber, and hope for the best. There are a few problems here:
1- That can SERIOUSLY change the color of your dye bath and fiber.
2- This is the big one. You have dye molecules and mordant molecules all fighting for the same sites on the fiber to attach to. If the dye gets there first, the mordant can't attach, and then the dye will just rinse right off. Your results will be splotchy at best.
If you're going to take the time to natural dye, you have to know that it is NOT a fast process. Trying to rush it by skipping mordanting (or doing a poor job of it) will make your results not nearly so nice, and it is one of the things that turns a lot of people off of natural dyeing. Once you have your mordanting skills down, your results will be much more predictable and professional.
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