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Tips and techniques for using madder root to naturally color soap shades of pink. Also includes ways to use both powdered and whole madder, where to source it, and how to grow it. Madder root is a natural pink soap colorant that gives a range of shades from pale pastel pink to dusky cranberry.
Looking back, I think that madder root was the first natural soap colorant I ever experimented with. It was many years ago, and, at the time, there wasn’t very much information on how to use it. I played around, though, and tried using it in various ways. The results were terrific! Beautiful soft and natural pinks that were completely plant-based. I’ve now been using madder root since 2010 and have learned several ways to use it to color soap pink. Each method will give you different shades that are helpful when trying to get a range of pink tones that are completely natural.
This piece focuses on ways to use madder root, a natural pink soap colorant, in cold process soap making. Though you can use madder in other types of soap, the colors you’ll achieve and your methods may differ. For an introduction to cold-process soapmaking, start here.
What is Madder Root?
For thousands of years, people have used plants to create natural dye and paint. Madder, in Latin, rubia tinctorum, has been one of the most important plants during that time for achieving brilliant reds. It has been especially important to fiber and wool artisans, but madder has only become an important ingredient for soap makers in the past decade or two.
Though not particularly striking as a plant, its deep red roots hold so much potential! Madder grows as a herbaceous perennial plant with masses of stems adorned with whorled ruffs of star-like leaves. It grows in a thick mass, and the leaves and stems also feel slightly sticky, thanks to the many tiny hooks the plant uses to climb. In summer, madder blooms with small yellow flowers, and in autumn, they transform into dark black inedible berries. Growing instructions for madder are further below.
The ruby-red roots that can be as long as three feet are the prize, though. You can dig them up in winter when the plant is at least three years old. The roots are a bit of a mess, to begin with, due to their spindly growing habit. To preserve them for later use, dry them out for a couple of days so you can more easily shake the soil off them. Then you wash the dirt off the roots, chop them up, and dry them out completely. Once dried, they’ll last indefinitely and are an excellent natural colorant for soapmaking and fiber dyeing. Several natural chemicals in madder roots give red, pink, and saffron-colored dyes.
Is Madder Root Safe in Soap?
The short answer is yes, madder is considered skin-safe. However, nothing from the madder plant – the leaves, berries, flowers, or roots – is edible. Although you’ll find information online for taking madder for various health issues, it’s really unwise. Madder is considered by medical experts to be “probably unsafe“, potentially mutagenic (causes mutations), and carcinogenic (cancer-causing) if eaten. So please don’t try using it to color lip balms or as a self-prescribed medication.
Madder used in soapmaking is permitted since there doesn’t appear to be any evidence that it is not safe when used on the skin. There is some bureaucracy involved when using madder root in soap made to be sold to the public, though. That’s because it is not officially registered as an approved soap colorant with the FDA in the United States or with the UK or EU cosmetic regulatory bodies. Instead, you can add madder to soap for its “herbal properties “or an undefined reason. Essentially, madder is not considered unsafe when used in soap, and you’ll find it in stock with many trusted soapmaking supply companies. I use it and have no qualms recommending it for you to use in soapmaking too.
Growing Madder in the Garden
Madder is one of those plants you must understand will never be a beautiful border plant. It’s clingy, grows like a weed, and needs quite a lot of space. It can also be invasive! The plants also spread through underground runners, so if you can give them a sunny part of the garden to themselves, all the better. They will choke out and take over a bed if you plant them alongside other plants. Though a Mediterranean plant, madder grows happily in most temperate places, from California to England. Technically, it’s zone 6-10 by the USDA system, but I’ve also grown it in a pot before and can see how that could be brought in under cover if you have cold winters.
Start madder seeds indoors in the spring, two to four weeks before your last frost date. Sow each one a half-inch deep in a small pot with ordinary potting mix and keep warm, watered, and in a bright place. The seeds are essentially dried-out berries and look a bit like peppercorns. They can also take several weeks to germinate, so be patient. Once your seedlings have sprouted and grown a couple of inches, you can harden them off and plant them outside in sandy or free-draining soil. Slugs love madder seedlings, though, so take precautions against them.
Also, I’ve spotted some people saying that madder plants need to grow in a hot climate to produce vibrant reds. This isn’t true, and madder has a long history of being grown in Britain, beginning in the medieval period. Thanks to British-grown madder, British soldiers’ uniforms in the past (the “Red Coats”) were so vividly red. To ensure that your plants produce intense reds, you can sweeten the soil each winter by sprinkling garden lime over the ground that they’re growing. The leaves wither back in winter, and you can pull the dead foliage aside to amend the soil.
Caring for Madder Plants
Once your plants get going, they can grow a good couple of feet tall and benefit from something to grow against. A trellis is a good idea since it will give the plants structure and help stop them from flopping over. Madder is a low-maintenance plant once established and won’t need much attention. However, the color you’ll get from madder roots will be more intense if you sprinkle lime on the soil each winter.
Madder is also an investment as a harvestable plant. Though some sources will have you harvest the roots after only a couple of years, it’s better to wait for three to five years before digging. This is the advice Teresinha Roberts gives, the dye-plant gardener that I feature in the natural dyeing section of my book, A Woman’s Garden: Grow Beautiful Plants and Make Useful Things. After five years, the roots will be pencil-thick, easier to clean and use, and have more vibrant dye potential.
How do you use Madder Root to Color Soap?
If you don’t have a garden or want to grow madder, you can still source it from soapmaking and fiber-dyeing supply shops. For personal use in soapmaking, ensure that the madder root is pure, and you can use it for your batches. If you’re making soap for retail, you should use a product with traceability and documentation, so it’s best to get madder from a cosmetic soapmaking supplier. You’ll notice that madder root is supplied as either a powder or as pieces of reddish-brown root. Both work well in making madder root soap.
Madder is both oil-soluble and water-soluble, which means there are a few different ways to infuse it into your soap batches. However, the method you use to introduce madder root will determine the shades you’ll get in soap. I believe it has to do with the color chemicals in madder, alizarin, and purpurin, having different solubility in oil vs. water. The color derived from the outer reddish part of the madder root also yields a different color than the root’s inner part. So, in theory, using whole roots versus powdered madder could also give different hues. I’ve not fully tested this, though.
Another thing that you’ll notice when using madder in soapmaking is that the colors can morph dramatically. The compounds in madder transform into colors through the reaction with alkaline substances, such as lye. As the pH of the soap batter and bars change, so can the color. Often this means that vivid red hues fade into dusky pinks as the pH begins dropping to a skin-safe level.
Lastly, gelling and the quality of madder root will affect the deepness of color you’ll get in your soap. Quality can vary depending on where and how the plants were grown and how the roots were preserved. Gelling is explained further on.
Madder Soap Recipe Using an Oil Infusion
Probably the most beautiful shades of pink you can get from madder in soapmaking begin by infusing the roots in oil. Though you can infuse madder root powder in oil, you’ll get a much better result using dried root pieces. Madder root powder tends to sink to the bottom of the oil and create a sludge that doesn’t seem to want to infuse very well. At least, not without regular and vigorous shaking!
It’s also better to use the whole roots if you want to avoid specks in your bars. Add the madder root to a glass jar, pour over a liquid oil, such as light-colored olive oil, seal the top, and allow to infuse for two to four weeks. Keep the glass out of direct sunlight during this time since UV light can damage the oil, but ensure that the glass is in a warm place. A shake of the jar every now and again is a good idea too, but optional.
After the time has passed, you can strain the oil from the roots using a small sieve and/or cheesecloth. At this point, the oil will not look very pink at all, and you’ll wonder if you did something wrong! Don’t worry, the orange color of the infused oil changes to pink during the soapmaking process. After straining, you can use the oil to replace all or some of the oil in a soap recipe. For example, if you’ve infused madder into olive oil, you can replace all or some of the olive oil in a recipe with madder-infused olive oil.
As for ratios of madder to oil, I recommend using 6 Tablespoons (25 grams) of dried madder pieces for every cup of liquid oil. You can use more or less madder if you wish, though, and half of that amount works for a light pink. I won’t give a weight for the oil since weights are different based on which oil you use. For a larger batch, infuse 3/4 cup (100 g) of madder root pieces in one quart of liquid oil. You can work out the math if you’d like to infuse more.
Making Madder-Infused Oil in a Crock Pot
A quicker way to make madder-infused oil is with a direct heat source. You can use the oven, a stovetop, or, more commonly, a crock-pot (slow cooker), depending on what you have. The idea is to warm the oils and madder at a relatively low temperature to help the madder infuse into the oil quicker. Because you’re heating the mix, you also melt the oils, so you can infuse madder into solid oils such as coconut oil, cocoa butter, or shea butter. For really deep pinks, you could infuse madder into all of the oils in the soap recipe! The downside of this method is that it uses electricity, which is why the cold-infusion method (and patience) actually pays.
To use this method, use the same or similar ratios of madder to oils as given above. For the stove-top or oven methods, place the oil and madder in a heat-proof container with a lid. An old and clean jam jar is perfect! For the stovetop, you’ll need to use a double-boiler method to avoid direct heat on the bottom of the jar. Fill a saucepan with water and place a rag at the bottom. Put the jar on top of the rag and then put the pan on the hob and bring to a simmer. Keep it just below simmering for three hours, making sure the water doesn’t fully evaporate out of the pan. For the oven method, simply place the sealed jar inside the oven at 190F (88C) for three hours.
For the crock-pot, just place everything into the main dish and turn the unit on to low. Allow to warm and infuse for three hours. No matter which heating method you use, you should strain the madder from the oils shortly after the infusion time IF you added solid oils to the mix. They’ll begin to solidify a bit as the temperature cools. If it was just liquid oil, you could leave the infused oil to cool to room temperature before straining. Use a fine mesh sieve and/or cheesecloth to separate the madder from the oil.
Add Madder Root to Lye Solution
When you add madder root to the lye solution, the color can be astonishingly vibrant at first. Think ruby-red and burgundy! Unfortunately, madder soap recipes made using this method often lose much of their color during the curing phase. The color range you’ll get is more of a warm pink color than a true pink, as well, but still very beautiful.
To use this method, add madder root directly to the freshly mixed and very hot lye solution. When you’re ready to use the lye solution, strain it through a fine mesh sieve and into the soaping oils. Make the soap as usual from this point.
The amount of madder you use in this technique will affect the final color of the soap. For the darkest layer in the soap photo above, I used 2 Tablespoons (8.3 g) of dried madder pieces for a 1-lb (454 g) batch of soap. The middle layer was one teaspoon (1.3 g) dried madder pieces for the same size soap batch. I created the lightest color by using only ¼ tsp (0.35 g) madder.
Caveats for Adding Madder to the Lye Solution
When adding madder to the lye solution, it can be better to use dried madder pieces rather than the powder. Again, it helps you avoid specks in your bars. However, too many madder pieces can cause a big problem. I’ve found that madder pieces will soften and expand in the lye solution and absorb some of the liquid. That’s fine for relatively small amounts of madder, but keep this in mind if you’re planning on using lots!
I once tried making a batch this way, only to have the soap not set and turn into an oily mess. It was likely because there wasn’t enough lye in my recipe after the madder had finished absorbing the lye solution. In that case, I used 30 g (6 TBSP) of madder to 160g of distilled water. The madder pieces were pretty bloated when I disposed of them, and I only really clocked the issue after the fact.
Stirring Madder Root Powder into Soap
The easiest way to make madder soap is to blend powdered madder into the soap while you’re making it. The pink colors you’ll get from this technique are soft and warm, with specks of darker pink or magenta throughout. Again, the amount of madder you add will affect the intensity of the color, but the more you add, the more chance you’ll feel the madder pieces in the soap. Too much, and the texture may feel scratchy.
I find that if you use moderate amounts of powdered madder, you won’t feel much of anything, though, and that’s how I make my rose geranium and lavender soap. It’s when you start heaping madder powder in that the soap turns into sandpaper! I’ve seen some people do this to try to get dark colors, but it seems that the effect is at the expense of usability.
Typically, you can successfully use ½ to 1 tsp of madder root powder per one pound of soap (454 g) of soaping oils. The photo above is of soap made with ½ tsp madder root. When using this method, I sprinkle the madder root powder over the solid oils in the pan before they begin melting. That way, the madder powder warm-infuses into the oils before adding the lye solution. It can add a bit more color!
If you’re making a soap recipe that doesn’t require melting oils, such as a castile soap recipe, mix the madder root powder into a wet paste with a bit of the oil before adding it at trace. That helps it disperse evenly and stops the madder from forming clumps in the bars.
Creating Madder Root Pencil Lines
Another fun way to use madder in soap is to sprinkle it as a powder between layers of soap when using a loaf or slab mold. It creates a fine line that runs across your soap called a pencil line. You can use various powders to make them, but madder has the added effect of bleeding slightly into the soap above and below, creating even more visual interest.
To create a pencil line in soap with madder root powder, you first pour soap batter into a mold and settle it. Cover this soap with a fine sprinkling of madder powder using a fine mesh sieve. It’s pretty much like dusting a cake with icing sugar (powdered sugar). If you try to do this without the sieve, you will likely get large chunks of madder and an uneven distribution of the powder. I don’t recommend trying it. Madder powder will also get on the mold during this step too. Carefully wipe it off before proceeding, or it will color the outside edges of the soap.
Once you dust the powder on, pour more soap on top – do this carefully, though. The best way is to hold a spoon or spatula just above the soap in the mold and pour the batter onto the spoon. This step lessens the force of the soap batter and helps stop it from disturbing the pencil line layer. After the soap mold is full, allow the soap to harden and cool before cutting.
To avoid dragging the madder through the bars, turn the finished soap loaf on its side and cut it that way. You may also see some madder powder on the outside of the bars from where the dusting of madder powder stuck to the mold. It doesn’t wipe off very well, but you can trim the edges of the bars with a potato peeler to remove it.
Gelling Madder Soap Recipes
For vibrantly colored madder soap, ensure that the soap enters gel phase after you pour it into the mold. Gelling is a heat-induced development in soap that happens during the initial stages of saponification. After you pour the soap batter into a mold(s), the lye solution and oils interact to form soap. This interaction is called saponification, and it produces extra heat. If this heat is sustained in some way, then the appearance of the soap will become glossier, and the color will deepen. It’s a purely aesthetic effect and optional in soap making.
Without gelling, madder soap recipes will often finish as a matte pale to dusky pink. Some even begin as a pale lavender color but will eventually turn muted shades of pink. It’s a lovely shade of pink, in my opinion, but a lot less vibrant. If you gel madder soap, the pinks will intensify! You’ll get everything from true pink to deep salmon.
To gel soap, you can insulate it or oven process it. Insulating means wrapping the soap with something that will keep it warm such as a thick, fluffy towel. Just make sure it doesn’t touch the soap. You can then either leave it on the counter or put it in a warm place. If you use this method and make smallish batches, you should consider slightly warmer soaping temperatures (110-120F / 43-49C) or work in a warm room. Doing this will help the soap to gel fully, rather than just in the middle.
Oven processing can be easier and more effective, though. While making the soap, turn the oven to 170F (77C). Once you pour the soap into the mold, put the mold inside the oven and turn off the heat. Leave the soap inside, without opening the door, until it’s cooled down. Twelve hours to a full day should do. Soaping temperatures for this method are flexible, and I often make soap at 100F (38C), and oven processing fully gels it. One thing I do for oven processing small batches is to place the soap in a paper shoe box when it goes into the oven. It helps to keep smaller batches warmer for longer. Just please make sure that the oven is off at all times if you do this.
Natural Pink and Red Soap Colorants
Madder root is an exciting natural soap colorant to use if you’re aiming for a wide range of pinks! Using each of the techniques explained can give you different shades and effects and make the most from a sachet of madder root. Other natural soap colorants can give you pinks, though, and some are just as beautiful.
There are also some other wonderful natural colorants that you’ll enjoy using too. Annatto seeds for orange, indigo for blue, alkanet root for purple, and so much more. As a taste, here are some ingredients and techniques that you might want to explore:
- French Pink Clay Soap Recipe (rose clay)
- Magenta-red Rhubarb Soap Recipe
- Pink Cochineal Soap Recipe
- Full Natural Soap Colorants Chart