Black beans... black beans took multiple trials and a whole lot of errors. I'm still not thrilled with the results.
Recipes and ramblings under break
After seeing beautiful pictures online of the sky blues and rich cobalts people were getting from their black bean dye batches I decided to try my hand at it. It is theoretically a very simple process - you soak some dried black beans overnight, separate out the inky blue liquid, and then soak your wool in that for a day or so. You can even eat the black beans after (assuming you didn't add anything else to the dye batch). It didn't work the first time. Or second. And it only sort of worked by maybe the fifth trial. And I never got a true blue from it.
So... rather than list out all the trials let's skip to lessons learned. What a fussy dye.
TLDR: Mordant everything, add some baking soda, keep the lid closed, put your fiber in tights, and don't heat it up.
Most important is to soak the beans in water with a basic pH or else it will never develop blue tones. My water is slightly acidic so after a couple failed attempts I started dissolving a little baking soda in it to counteract the acidity. I would suggest doing it preemptively to anyone planning on attempting it themselves, unless you do happen to know the alkalinity of your water. Slightly acidic water results in a brownish purple liquid that not pretty or colorfast.
Due to this, it seemed like a good idea to add some ammonia (which is a base) and try the "leave it in a jar and see what happens" technique. The liquid turned red, like it does with an acid, and wasn't colorfast either. My assumption now is that this dye only works for a small range of pH values close to 7 (neutral), and anything too far from that yields reddish brownish liquid that won't dye anything.
When soaking the beans to prepare the dye liquid, it is apparently important to do it in a container with an airtight lid. Conversely, you need to open the lid a few times during the soaking process because the beans expand and release gas and the whole thing becomes pressurized. After doing it a couple times in a jar, I left it uncovered overnight. The night before I had a nice inky blue mixture in slightly alkaline water. In the morning; greenish brownish non-colorfast sludge. Reacting to the oxygen maybe? I don't make the rules, just cover your stuff.
The other important thing, which I read about luckily and did not have to experience myself, is to make sure that when you add the wool to the dye the wool never comes in direct contact with the beans only the bean liquid. It discolors the wool and prevents the blue color from developing. This can be done by straining out the beans, pouring off the top liquid after the beans have had a chance to settle, or putting the wool in a pair of tights which allows the liquid through but no bean particles. Having done all three, the last is my favorite because it requires the least amount of effort and you can sort of weigh the wool down with the beans to keep it totally submerged.
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| Closed lid, alkaline water, wool in a pair of nylon tights, not being heated |
Well here are some results, such as they are. The closest I got to blue was a light cornflower once, but this did pretty consistently make a pastel turquoise.
1) Mordanted wool soaked once overnight (in airtight container, in alkaline water, in a pair of nylon tights) - it's not quite as dark as the picture
2) Mordanted wool allowed to fully dry and re-submerged in dye again overnight - only a bit darker than the original
3) Dye exhaust - the third time this dye was used there didn't seem to be much pigment in it, but it was enough to tint the wool a little turquoise
4) Heated dye in the microwave slowly over the course of half an hour and allowed to cool - turned a dull grey brown color, lost most of its blue tone and is ultimately lighter than cold soaking the wool. I wouldn't recommend heating this dye.
5) Dye soaked once and treated to an iron sulfate after bath - the mixture turned green and curdled looking, but washed out to reveal a darker and slightly more purple color
6) Copper sulfate after bath - I don't think the color has anything to do with the bean dye, I think it's just the color of the copper sulfate
I'm not sure I'll be doing any further experiments with this. It has proven to be a very fussy dye, and while I don't think that everyone else posting about this was lying, I do think you need to hit some magical chemical equilibrium for this to work well. Maybe just the right water and the right brand of black beans.
Honestly, when I need turquoise in the future I'll just microwave some Kool Aid.
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