Botanical Knits & Crafts, Yarn Dyeing

Natural dye tutorial: blue yarn from black beans!

EDIT: Want to see what I knit with blue yarn? Check out these other posts!

Blue ombre waves cowl   Green and blue striped socks

IMG_0312blue and green striped socks

Welcome to my dye tutorial, the most popular post on my knitting blog! This is a cold water dye using regular black beans, designed to be used on yarn made of wool or other natural fibers (it won’t work on cotton, acrylic, etc.). There’s a lot of soaking time involved, so expect to have a finished product after three or four days. If you have a question, put it in the comments and I’ll respond. Enjoy!

Natural blue dye: background

I have a really awesome fiber dye experiment to share! As you can see from above, we got several lovely shades of blue —a difficult color to achieve —in a process that took about four days start to finish.

Now that I have a spinning wheel(!) and some wool, I’ve been wanting to learn about natural dyeing. Since blue is my favorite color, I gravitated toward information about natural blue dyes. Turns out there aren’t that many. Indigo and woad are the main ones, and they sounded like a lot of work for a first time dying project. Then I came across web posts on black beans as a blue dye. My favorites were blog posts at waysofthewhorl and brambleberriesintherain (now defunct), which then led me to the discovery that there is a ravelry discussion thread (login required) that is many years old and has hundreds of posts! Needless to say, I was overwhelmed with information.

At the same time, no one post seemed to describe exact amounts of beans, water, and yarn used, nor exact times for the different steps involved. So with a little help, we set out to do a test run with all the steps and amounts recorded. As a caveat, not everything went as planned, record keeping wise, but we did out best.

Tutorial: dyeing yarn blue using black beans What you will need (amounts will be determined later):

  • Black beans
  • Water (tap is fine and what we used, but see note at the end of the post)
  • Non-reactive containers for soaking and dyeing (we used glass and stainless steel)
  • Natural fiber yarn, white or off-white (we used Lamb’s pride, 85% wool, 15% mohair, M-10 Creme)
  • Alum mordant (Aluminum Potassium Sulfate—you can find this in the spice aisle of a well-stocked grocery store)
  • Cream of Tartar (also in the spice aisle)
  • Large non-reactive pot for the stove (We used a large enamelware roasting pan. Technically this should not be a container you’re going to use for food after this, and although alum seems to be non-toxic, I played it safe.)
  • Misc. items: additional yarn to tie off your skein in sections, a rack or other place to dry finished yarn, newspaper or something else to protect surfaces from dye
  • Optional: food grade tubing

Dye Prep Instructions

First, figure out how  much water and beans to use, choosing a ratio from below.

Here are rough ratios of Water to Beans in each of our dye lots:

  • dye lot  # 1/2  = 7 to 1  (7 parts water to 1 part beans)
  • dye lot #1 = 3.5 to 1
  • dye lot # 2 = 2 to 1
  • dye lot #4 = 1.25 to 1 [furthest hank on the right]

blue yarn in different shades

Each of the numbered hanks of blue yarn in the photo above is 1/2 oz (14 g) of yarn.

Make sure that you have enough beans and water to create enough dye for your yarn.  I strongly urge to get more than you think you need because beans absorb water at a higher rate than we bargained for. You’ll need enough dye to immerse your yarn.

Ratios work best, because our  actual measurements were rather odd :

  • #1/2 = 1/2 cup beans and 3.37 cups water;
  • #1= 1 c. and 3.4 cups
  • #2= 2 c. and 4.125 cups
  • #4=4 c. and 5 cups

Let each of these bean and water combos soak for 24 hours. This is a cold water dye, so it needs time. I preferred the glass jars for this.

To get the best dye, you’ll need to get as much of the bean water with as few bean particles as possible. From what I read, the pieces of bean tend to make the yarn more  gray than blue.

We strained out the beans, let the dye settle for an hour or two, then siphoned the water off from the top using the food grade tubing so that the bean particle matter did not make it into the final dye. . Other people on the internet suggested spooning the water out and leaving the dregs.

Yarn Prep Instructions

When are 4 hours away from completing your 24 hour bean soak, start preparing the yarn. Alternatively, you can do this part earlier and let the yarn stay soaking in the mordant pot overnight.

First hour:  water soak.

I separated my yarn into four 1/2 oz skeins tied with bits of a thinner yarn to keep them from getting tangled, then unwound the skeins and soaked them in water for 1 hour.yarn soaking in water

Second hour: Mordant on the stovetop

Mordant is what allows the dye to adhere to the yarn and not just wash out or rub off. After water soaking, I moved my yarn to large stovetop pot to mordant it using alum and cream of tartar. I used Sasha Duerr’s Handbook on Natural Plant Dyes to calculate how much need:

  • 8 percent of the fiber’s weight for alum
  • 7 percent of the fiber’s weight for cream of tartar

For mordanting 2 ounces at once this comes to about 3/4 of a teaspoon each of alum and cream of tartar. I will admit that I was probably closer to 1 tsp each, because I couldn’t find my 1/2 tsp measuring spoon. It still worked.


Dissolve the alum and cream of tartar into hot water and add to the stovetop pot along with enough water to cover the fiber. I added the water soaked yarn and brought the pot to a simmer.**Important note: do not change the temperature of the yarn too quickly, it can cause felting** I simmered it for an hour then turned the heat OFF.

Final 2 hours: cooling and rinsing

I waited another 2 hours until it had cooled off, then removed the yarn and rinsed it off with clean water that was the same temperature as the yarn to remove any excess mordant (using a little pH neutral soap is supposed to help).

Dyeing the yarn

Finally, the fun part—adding the yarn to the dyes! blue yarn in yarns As you can see, some of our dye lots barely covered the yarn, so we turned them upside down or right side up periodically to avoid unevenness in the color. We let them stay in the dye for 42 hours. I’m sure an even 48 hours would be great, but sleep comes first.

During this time, I discovered something that no other blog really mentioned: the color you see immediately can be quite different from the final color. Observe what the yarn looked like about 10 minutes after I put it in the dye:blue yarn first looked purple That’s right—it was a light purple color! At first I was disappointed that all our effort to get blue failed, but in an hour or two it started changing into the blue color you saw in the previous picture.

The photo in the blue plastic jar came from round two of dyeing the yarn. After I took out the four small test skeins, I still wanted to dye the remainder of the yarn. So I soaked and mordanted the remaining 2 ounces of yarn, poured all four dye lots into the blue plastic jar, and let it stay there for 48 hours. Not very scientific, although hopefully you can see in the photos that it came out a slightly grayer and more muted shade of blue—one which I still quite enjoy.

Drying the yarn

After removing the yarn from the dye, I rinsed them with lukewarm water and hung them to dry on my laundry rack (I wish I’d taken a picture then!) Here are  they are again, left to right from, darkest (1.25 to 1 ratio) to lightest (7 to 1 ratio), plus the extra hank made from all dye lots combined:

The darkest one is a distinctly deeper shade of blue than the rest. The difference between the two lightest shades is less subtle here, but in person you can definitely tell. And the last one of course has a distinctly grayer tone.

A note on the pH of your water

*The pH of your water can affect the final color of your yarn even if you do exactly what we did. I did some research and found out the tap water we used was rather alkaline, with a pH close to 8. I once saw a blog post that said they got a blue green color from acidic water. If you don’t know what pH your tap water is, you can use the red cabbage test to estimate it.

An updated note on colorfastness

Since creating this tutorial, I have gotten several questions about how much this blue color fades over time. The answer is yes, is does fade over time, but it still looks nice.

I made an ombre cowl from this blue yarn using this Wave pattern. Here it in 2012:

black bean blue dye ombre knit cowl in 2012

And here it is in 2014:

blue ombre waves knit cowl in 2014

So yes, the lighter blue yarns that were grayish faded to a blue gray over time. For more on this project, check out this post.  I still love this cowl!


54 thoughts on “Natural dye tutorial: blue yarn from black beans!”

  1. Thank you so much for this! Your four ounces would make beautiful baby booties. I am taking the masters spinners level 1 class from Olds College. We have to use 10 natural dyes for a portion of the homework. I am definately going to use this recipe. Can’t wait!

    1. Thank you! I haven’t really tested the light fastness of the yarn, and I’ve really only worn my cowl from it in winter. I have read that it’s the mordant that really affects light fastness, and alum isn’t as light fast as other mordants. However, it was the easiest and safest one to use, and it will be more light fast than no mordant at all.

  2. Mine turned out green! And not even a pretty green, a dull gray green. Soaking in vinegar now, just to see what happens. May end up over dyeing it. 😦

    1. Heather,
      Hmm, my two best suggestions are to make sure that none of the bean particles are making their way into the dye water, and to try using a different water source—my water is very alkaline, and I’ve heard acidic water tends to create green hues (see
      Personally I’ve been trying to figure out how to get a natural green dye of any shade! Green seems to be almost as tricky as blue to get right.

      1. I just came acrossed this, as I too would very much like to get a good blue natural dye. I am very excited about trying this one!! Thanks for the info on the ph levels also. We have very high ph water, so this could be making a difference for me. Nettles make a really soft green color. Just did a batch of alpaca/wool blend and it is quite pretty-muted.

  3. Hi!
    I did a cold water soak with bean juice for 48 hours, in a sealed glass container. Last night the juice started bubbling out? It’s not very warm here in Oregon, so I’m confused as to why it’s fermenting. And my yarn turned that purple color in your photo–although a bit deeper. Wondering if exposing it to air changes the color? So curious!
    Anyways, thank you for your post!

    1. That is curious! How long did you soak the beans in the water to make the dye, and were those containers sealed too? I noticed that the longer the beans soaked the more the more they smelled, so it might be a contributing factor, along with any bean particles that made it into the dye. Good luck with your yarn!

  4. Thank you for being so thorough! I had some of the some questions about ratios and timing. I did want to add, though, that alum IS toxic in higher levels and can be irritating to the skin but is considered safe in small amounts. It’s what canners use to keep pickles crispy.

  5. Hi! I am from Panamá and i was just looking for something local to dye naturally blue and you are the shine! I am just wandering, i just want to dye cotton.. yarn is to hot for this climates. Do i need to use creme of tartar? and do all this procedure.
    Normally I used turmeric and achiote and i use alum and the natural dye all pack together for my dying no separated steps.

    will aprecciate your insights

    hasta luego guapa!

    1. Hi debora,

      As I understand it, the creme of tartar helps the alum to not feel as “sticky” on the yarn and the dye to absorb more evenly. It’s not required but it has benefits.

      I’d love to see how your cotton yarn turns out with black bean dye! I’ve heard cotton absorbs natural dye differently. (This webpage has a good comparison of wool versus cotton in natural dyeing: You might end up with a different shade of blue or a even different color!

  6. I love your post 🙂 It’s a bit funny because I did the experiments one black bean with Cecile from Ways of the Whorl (the post you refer to) gosh back in 2011. I love how this is so circular. Now I am reading your fab post to help me recreate the experiment. BTW I love your picture of the cowl two years later. I have recently had several people tell me that this and that is not colourfast, but the truth I think is that no dye (even synthetics) are colourfast if you leave them in the wrong conditions. I thing that this is the charm of natural dyeing. If the colour starts to fade or change, maybe you will love the new colour even more or perhaps you can overdye and get a third colour. It’s all just a fun experiment, and I love it.

    Eddie from Eddie’s Room (

  7. I am in th middle of dying some wool and can’t wait till tomorrow till I can take it out. Wondering though why it doesn’t get heat set like so many other dyes? Would simmering it for an hour have the same effect as the 48 hour soak? And maybe make it more colorfast? I just started another batch of beans soaking and thought that maybe I would try that method?

    As a science teacher I really like your scientific method… Thanks

    1. I would not use heat with this dye, as it is extremely sensitive to temperature and pH changes. If you look through the ravelry discussion thread, you’ll notice that dyers who used heat tended to describe their results as being grayer and paler and not very blue.

  8. HI I just wanted to thank you for your post. This project made for a great homeschool experiment. We have been trying our hands at natural dying for the last few weeks. We loved your blues and the second blogs beautiful green. We were actually hoping to achieve both colors. so we did the cabbage test ( great fun with the kiddos) and decided to run a batch with our well water ph of 9, sea salt ph of about 8 and white vinegar to get an acidic dye. we were initially disappointed when we got a blue and a purple so we decided to mix up a batch with soda ash we had from tye dying and it immediately turned green. So we have concluded that it is actually alkaline that causes the green.(we believe that when she added the baking soda to her soaking beans that created an alkaline environment) Now we are just hoping wool holds up to soda ash. We only put 1 tsp in 2 1/2 cups dye. Thanks for posting such a scientific tutorial which really got our brains rolling 🙂

  9. Reblogged this on Urban Meliad and commented:
    Reblogging this so that I can find it later.
    Garden plans currently include the possibility of growing “Zorro” black dry beans specifically for dying purposes, though they won’t be a priority for me. 😉

  10. About the green color: that author said get well water was acidic, and so she compensated by adding baking soda to the mix.

    Next time you feel like playing around, get a bit of bean dye in a bowl and add a splash of vinegar to it. You don’t get green. You get red! After that, add a splash of ammonia and watch it turn green. It wasn’t her well water. It was the baking soda.

    Meanwhile my first test didn’t appear to have any sediment so I skipped the “settle and siphon” step. Guess who has gray dye now? Sigh. 🙂

  11. I am trying this dye also and have read various accounts. Appreciated your attempt to keep good records and report your measurements. I read about a cool test, that I did, where you put a bit of the dye into 3 glasses. The center one you leave alone. The one on the right you add a bit of vinegar (to lower the pH), while the one on the left you add a bit of baking soda (to raise the pH). This way you can see if whatever dye you are trying is sensitive to pH. Well– yes! The acidic turned pink while the higher pH turned blue green. I’ll see what the middle dye actually does to my wool. Have 2 days to wait. I’m hoping for blue. –Lisa

  12. What an awesome idea! I’ll have to try this out. Maybe I’ll experiment with the pH and try out the green and pink versions. Think of the possibilities~!

  13. Be aware that not all black beans will give you blue. Some of them will give you browns and greys. The soak water won’t have any tint to it. My first time I got beautiful blues. The second time I got beans from a different store and they did not give any blue.

  14. I did a test skein in about February that was blue-ish (I didn’t use enough mordant, I think), and just yesterday I pulled it out and it was already smoke gray. It hasn’t been exposed to sun or wear and tear. Any idea what may have happened?

    1. I recently read Chris McLaughlin’s book “A garden to dye for: how to use plants from the garden to create natural colors for fabrics and fibers,” which calls black bean dye a fugitive dye—that is, it fades over time, even without sun or water exposure. In my experience, the stronger the color is at the beginning, the less it fades to gray. I made a comparison photo of my black bean cowl in 2014 and in 2012. The lightest blue faded almost to gray there, but the deepest blue stayed more blue:

  15. Wow thanks so much! I know that this is quite an old posting but I am so glad I found it! I have been working on getting my blue, bluer! I have been using black beans for quite a while now, but have never been super excited about how it has turned out. But I AM NOW! This batch turned out amazing! I used organic Black beans (my first time using organic ones) and soaked them for 48 hrs. I also used Alum for the first time (I skipped the cream of tartar though because I didn’t have any). Also I soaked the fabric in the dye for 48 hrs. I just took everything out and boy am I pleased! I’ll be updating the new and improved color on my website soon! Thanks again!!!!

  16. Your information has given me some greater insight into what I am doing. Today I dyed a skein of wool and one of cotton with black turtle beans. I used a vinegar and copper mordant that had been prepared previously. My tap water is soft and turns cabbage stock pink. The colour I obtained is a strong reddish brown! I was trying for blue but thought it would be a different colour. My lavender and lemon juice came out yellow brown, not pink. I can make some beautiful oranges with gum leaves or lichen and no mordant, and I made a good black with acorns, rust and vinegar. I generally get browns, which are good for socks.

  17. I have tried again for blue with beans. I used black beans, (not black turtle beans), and did not use heat, just water the beans had soaked in as a cold dye. My wool turned blue and then a bit grey blue, Next time I will take it out sooner, say after 24 hours rather than a few days. The cotton was blue at first but only on the outside of the skein, like a coating. I pulled the strands apart to let the dye over the hidden parts. Now the colour has changed to a reddish grey. I will continue using the black beans and intent to use seawater next time with the no heating method. I think a higher pH than my tap water could take the slight green away and perhaps produce a clearer blue.

  18. I am still going with the bean dye and my last batch was black turtle beans, cold soaking of the beans and then using the water to dye wool and cotton yarn by cold soaking. Air temperature is sometimes close to freezing at night but the days are cool or warmish. Although the beans were soaked in tap water, some seawater was added after the beans were removed. The wool came out a beautiful violet after after 5 hours soaking and then the second batch in the used dye, silver grey-violet. The cotton was in the dye for days and came out inky blue with pink high lights. (I have no problem with the dye becoming stinky as it does not decay noticeably.) The cotton is drying out but continuously changing colour. It went from blue-purple to purple. When I checked it just now, it was purple on the outside with green it the hidden parts in the middle but where it touched the wood of the hanger it was folded over, it was purple. It was in gentle sunshine at the time. The colour changes with the time of day. The effect is less dramatic with the wool, it is greyest in the morning and turns more purple in the sun. My original wool from another batch is not dull blue anymore but a greenish grey blue. The change has been slow and continuing after it was dry.

      1. I love the colours I have been getting especially the purple and mauve, but I felt it as a challenge to get blue. Yesterday and today I made a very strong beautiful blue on wool. This was done by soaking black turtle beans in seawater. I boiled the seawater first as I wanted to eat the beans without risking a stomach upset. I cooled the water before putting it over the beans. I soaked them for a few days as the weather is cool enough for them not to go stinky. The first length of wool, which was a sample to test out what would happen turned a lovely blue. I find that the colour does not get stronger if left in for more than two hours on wool, so I take it out. Next I divided the dye into two bowls and put in rusty water or water that was green with copper oxide. (I have jars of water with bits of old iron bed springs or copper off-cuts to make these.) The addition of rust produced a deeper blue and the copper a very slightly different shade of blue. Using both iron and copper containing water produced a colour like using just copper.
        Today I took another lot of water from my beans which had soaked in tap water over night, (I wanted the seawater out of them so they were not so salty). Again I tried short lengths of wool and produced beautiful blues under all conditions, so I did a whole skein with the iron and copper and achieved a really strong beautiful blue within a short soaking time. At no stage did I heat the dye and I suppose the air temperature is about 12 degrees C during the day.

    1. I make black bean soup!

      The most recent time I made black bean dye, I started soaking the beans on Friday evening. On Saturday morning, I put the pre-mordanted yarn in the dye, and the black beans in my slow cooker. Both were ready by dinner time.

    2. If you intend to eat them it is important that they are kept fresh. I have found soaking them in the fridge is fine and soaking for 24 hours or even just over night works. Sniff them and if they are unpleasant, they are off.
      How many beans can you eat? My family haven’t complained yet but it is good to try many different recipes. Fritters, soup, salad, in sauces, with cooked green vegetables and fried onions, minced and mixed with eggs and wholemeal flour, then baked: -the cookery is part of the fun.

  19. I love the clarity you are providing, but for 1lbs of fabric (a cotton shirt) how many cups of dye to get color #4? What kind of a mordant would you recommend for cotton? Thanks!

  20. I have taken a beautiful purple bean dyed cotton thread out of the dye and as I have a lot of that colour, I was willing to experiment and risk creating a less desirable colour. I then washed it with soap and as I did so it turned the same blue you have. It is drying blue.

  21. Pingback: Fredagsfund: Natures farver – det gode nok liv og andre tankefuldheder
  22. Great tut thank you. Do you know what could stop the color running when you soak a knitted item for blocking?

  23. Are the beans from a can, or dry? If dry, rehydrated? So, if I want to do the dye lot #4, do I measure dry, or rehydrated/canned beans?

    1. If I want the deepest color, at a 1.25/1 water to bean ratio, the water will soak into the beans (and not fully rehydrate them, at that, if that were my plan) and I would just have beans, no water. Do I keep adding water?

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