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Natural Dyes for Wool: Logwood

By Hannah Thiessen on May 18, 2021

how to dye yarn

Logwood is a family of trees also known as “bloodwood” in some parts of the world. Found in Mexico, Belize, Central America and Australia, logwood can be found in extract, powdered, sawdust and wood chip form from many natural dye sources. 


I had avoided logwood for some time because I am just not a huge fan of purple! However, as I worked my way through so many natural, wood-based dyes as part of this series with Knomad, I began to think that maybe I should try my hand at the lavender tones achieved by this natural dye. As I began researching, I read a lot about how logwood was one of the goods traded, stolen, and sold en masse during the Golden Age of Piracy (1650-1726 A.D.)


As we explore these dyes from history, it’s important to note that thousands of years of research have been done already to help determine the best way to extract exactly the color we desire. Through reading books and blogs on the subject of natural dyeing, I think you’ll be able to achieve a variety of effects from logwood, and it’s a material I hope to keep experimenting with in the future! 


how to dye yarn


How to Naturally Dye Wool with Logwood


For this dye experiment, you’ll want the following materials on hand. Remember, anything you use for natural dyeing must not be used again for food or food prep at any time, and you’ll want to store it separately to avoid any cross-contamination. 


  • 1 large stainless steel or aluminum soup pot or stockpot

This should be big enough to hold 1-2, 100 g skeins of yarn, covered in water, and fully submerged with room to move around.


  • Dedicated tools: measuring cup, spoon for stirring, measuring spoons


  • A heat source

This could be your at-home stove with good ventilation, a hot plate, a propane burner, or even a crockpot. If you’d like to use an upcycled crockpot, you will not need the stockpot, but it will need to stay fully dedicated to natural dyeing as dyes are not food safe.


  • A water source

Natural dyes do use a lot of water–for prepping your fibers, creating dye baths, and rinsing finished yarns. You can use rainwater if you like, especially if you find your tap water is influencing your colors negatively. You can test your water’s pH with strips and see how ‘neutral’ it is if you like as a starting point to alter colors to be warmer or cooler. How you alter these will depend on the dye you’re using. 


  • A respirator or face mask

I typically would not use a respirator or face mask when moving around larger dye goods like flowers or leaves, but if you are using anything powdered–the chemicals we use to mordant, or any powdered dyes–I recommend having one on. These ultra-small particles just aren’t good to breathe in! 


  • A scale that can measure grams in small quantities

If you already have a baking scale, you can use it here, just make sure not to let any dyes or materials touch the scale directly. Simply use the tare function to zero out the weight of any vessels you’re using to measure, then clean off your scale thoroughly after use. 


  • Aluminium sulfate or Aluminium Potassium Sulfate*

Mordants are chemicals that bind to both the fiber and color, acting as a bridge to attach color molecules to your wool. This chemical is the safest of a handful of options and is popular with many natural dyers. It will only bind color to protein fibers, not cellulose ones–so color taken by the wool may not be taken up the same way by any blended fibers (like cotton, hemp, linen, or nylon). 


  • Cream of Tartar*

Cream of Tartar adds a little softness back into your bath and prevents your wool from feeling too crunchy at the end of the dyeing process. 


  • Logwood powder

I’ve used a pre-prepared, ultra-fine powder for this experiment. Depending on the year, the age, quantity and source of your powders, some colors may appear differently. 


For this dye experiment, I selected Knomad Spark, a decadent 100% Organic Merino wool yarn with 219 yards per 100g hank. I chose this base for how bouncy it is!


  • Old clothes

Logwood dust has a way of making it onto whatever you’re wearing and making it look dirty. Wear something you don’t love when working with any natural dyes. 


  • Gloves

Rubber gloves or kitchen gloves, which can be reused multiple times, are my preference here. While most natural dyes are perfectly safe to handle with your hands, you’ll be washing, rinsing, and in and out of water a lot, which can damage your nails and cuticles. Keep those knitting hands pretty and get some gloves. 


*These items have been pre-calculated in the amount you need for this project, dyeing 200 g of wool, however, you can also do your own calculations using the mordanting guide below. 


how to dye yarn


Step 1: Prep your fiber. Knomad pre-scours and washes their yarns before shipping them to us, so there should be no need to heavily clean the fibers–simply remove the tags, leaving all the ties, and open the hank into a big loop. Add reinforcement ties if you feel they’re necessary, and soak the fiber in warm water for an hour to get it fully saturated (typically 1 hour). 


Step 2: Measure the alum. Wearing a respirator or face mask, measure out 12% of your weight of fiber (WOF) in alum sulfate. Here’s the math for our experiment: 


200 x 0.12 = 24 g of aluminum sulfate

Hot tip: weigh out how much alum is in a tablespoon (dedicated tablespoon) and then calculate moving forward about how many tablespoons you’ll need to simplify future measuring. 


Step 3: Add hot water to your alum in a small mixing container. I like to use empty, recycle-ready plastic containers. Stir the alum and water mixture until the alum is fully dissolved and the water looks cloudy or clear, but has no visible grains in the bottom of the container. Measure out 1 tbsp of Cream of Tartar and dissolve it into the water while it’s still warm. 


Step 4: Transfer your mordanting solution to a larger stockpot, and fill with enough water to cover your skeins of yarn (don’t add them until the pot has all the water in it). Stir and then add your yarn, moving it around to let it fully absorb the mordanting solution. Set on low heat and simmer (do not boil) for 1 hour. Allow to cool overnight with the yarn in the solution. 


Step 5: Prepare your dye solution. 

Measure out 1 tsp of your dye powder per 100 g of fiber and see how you like the results. Often, these powdered dyes are a bit more potent and require less dye to fiber in the ratio. Powders should be prepared with smaller quantities of water and left overnight to more thoroughly mix, or these dyes have a tendency to separate and make one part of your project darker than the other (or have little speckles, which can be cool, if that’s what you wanted). I mix powdered dyes up in a bottle with a well-sealing lid, fill the bottle halfway with water and shake a few times over the course of the day. Leave it overnight in the bottle. Logwood specifically looks very dark and almost reddish-purple when first made, but deepens to a softer, cooler purple. 


Optional modification: If you’d like an even cooler purple, add a bit of Lac. I really loved the color that came out on this handmade mini tester skein. 


how to dye yarn

Step 6: Prepare the yarn. Drain the water from your yarn soak, and push a little of the extra retained water out with your fingers. Not too much–liquid being held by the fiber will help draw the dye into the yarn, so we don’t want to take it all out and risk too much splotchiness in the final fiber.


Step 7: Prepare the dye bath ahead to allow the logwood enough time to dissolve. Logwood extract dissolves beautifully in hot water, but if you’re using chips you’ll want to do an overnight soak. To get lavender tones, I used 2 tbsp for 200g, but you should play with a variety of materials and concentrations to get a purple you love! 


Step 8: Add your yarns gently to the dye bath, making sure that yarn has enough room to move around but is mostly submerged in the pot. If you need more water, it’s okay to add some here.


Place your pot on the heat source of your choice and increase the temperature gradually to a heat just under simmering. If you have a thermometer, you’re going to first lift the temperature to 90 F (32 C), stir, and then lift the temperature again to 180 F (82 C). I don’t have a thermometer, so I just eyeball it, and that’s okay too. You want the water hot enough for steam to be rising off it, but not so hot that it’s bubbling, boiling, or moving your yarn around for you. Keep the dye bath at this temperature for an hour, stirring occasionally to move the fibers around and keep them from collecting dye only on one side. After an hour, turn the heat off and let it cool. 


Step 9: Lift a bit of your yarn from the pot with a spoon and evaluate the color–remember, it will typically be 1-2 shades lighter than what you see on the wet fiber. If you like the color as-is, remove the yarn from the pot and move to the next step. If you would like to see the color deepen or strengthen a bit, leave it in the pot overnight, stirring one more time before you go to bed. I kept one skein in the dye pot and rinsed the other one right away, and the difference is 1-2 shade levels. 


Step 10: Remove your yarns from the dye bath and smoosh out some of the extra dye–set the wool aside. Fill a sink, basin, or bucket with room temperature water and add your yarn, moving it around with your hands to allow dye release. When the water is dark, drain it and do this step again. Rinse until the water is mostly clear to ensure that no dye particles will transfer to hands or clothing while working with the finished yarns. If you want, you can add a little bit of wool wash to one of these rinse baths to improve the softness and scent of your finished yarn. 


Step 8: Hang your hanks of yarn to dry out of the direct sun (I like to use a portable hanging rack). They will drip a little bit, so if you need to dry them indoors, I suggest putting them in a bathtub or in a room with a drain (like a basement). Depending on your humidity and weather, it can take 1-2 days for yarn to fully dry, but maneuvering it so that the same part of the hank is not always hanging down can help move this process along a bit. Logwood drips will stain things purple, so if you have an enamel tub, try to hang them outside!


I’m pretty happy with my logwood purples but I can’t wait to experiment more and play with some layering of this color over my repertoire of pinks and browns to see what range I can get! 

how to dye yarn

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Hannah Thiessen

Hannah Thiessen is a passionate, self-proclaimed “wool obsessive”, who has worked in the yarn manufacturing, design, and production sector for the past decade. Through her books Slow Knitting (Abrams 2017) and Seasonal Slow Knitting (Abrams 2020), Hannah explores the relationship between the crafter and end project and seeks to provide a deeper, more holistic practice for fiber aficionados at all levels. On the Knomad blog, Hannah will be exploring natural dyeing on Knomad’s non-superwash bases, providing insight on the many natural dye products, extracts, and botanicals available to us, and expanding on the potential palette of color that surrounds us daily.

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