Woad Soap Recipe: Naturally Coloring Soap Blue (2024)

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Use this woad soap recipe to make natural blue soap with specks of darker blue throughout. Woad is a traditional dye plant used to create stunning blue fabric, wool, and wood. You can grow it yourself or buy the powder to make blue soap.

There’s nothing quite like growing a plant, nurturing it through its life, then finally using it in the kitchen or creative pursuit. A full circle of growing, harvesting, making, and finally using that has as much to do with the plate as with the soap draining dish. As you can guess, my main interest, aside from kitchen gardening, is making natural handmade soap. Blending raw ingredients like oils, dried herbs, and plant-essences to make beautiful bars using deliberate, skin-safe ingredients.

Beautiful is a keyword here. There are soap makers out there who stick with basic soap recipes that are more function than form. Useful laundry soap, soap for washing dishes, simple body soap, and the like. There’s nothing wrong with that at all. For most of my soap, I like to add a little more creativity though, and that involves naturally coloring it.

Naturally coloring soap blue

It’s possible to get a relatively complete range of colors in handmade soap by using plants and clays. That includes spices, seeds, bark, roots, and leaves. You use various techniques to extract or use the color – some easier than others. One easy way is by adding Cambrian blue clay to your soap base. It’s a pretty shade that’s predictable and goes well with herbal essential oils. Probably the most stunning natural blue soap colorant is indigo and I’ve shared how to use it in soap over here.

WoadIsatis tinctoria, on the other hand, can be a little more involved. The pigment is in the long deep green leaves of the plant but needs extracting before you can use it in soap. I go over how it’s done in another piece. To skip this step, you can purchase woad powder from a reputable source. One such source in the UK is Teresinha Roberts, who grows and processes it herself. Woad for soap making is a deep blue and very fine powder.

Woad, a natural dye plant

When the Romans arrived in Britain in 55BC, they found the residents painted and decorated with woad. Caesar wrote that Britons “dye their bodies with woad, which produces a blue color,” and Pliny recorded that many of the women “stain all the body” blue with woad (an intriguing thought!). Another source, Claudian, a Roman poet, later described Britannia as being decorated with tattoos and dressed in an azure cloak. These are our first known references to woad as a dye plant.

Eventually, woad became commonplace as natural wool and fiber dye across Europe. It was only in the last five hundred years that it was replaced as a dye by indigo. Indigo itself was then replaced in modern times by synthetic blue dyes. Still, woad persists as an artisanal dye with those who work with natural fibers and cloth. More recently, soap makers have experimented with it as well. While it’s difficult to achieve the vivid blues and blue-greens of fiber dyeing, woad will naturally tint soap a pale blue-green, to pale blue, to deep denim. It’s a natural and soft blue in all its hues.

How to naturally color soap with woad

There are three ways to use woad to naturally color soap blue. No matter which method you try, begin with a soap recipe that doesn’t include a lot of yellow or golden oils. The reason being is golden oils naturally create cream to pale yellow colored bars. This warm color will interact with woad, giving you green bars in the end — it’s like mixing blue paint with yellow. So avoid extra virgin olive oil and other dark oils and butters and use recipes that include coconut oil, shea butter, and light-colored liquid oils such as olive oil pomace.

You can introduce woad to the mix by adding the powder directly to the lye-solution, infusing the liquid oils with it, or adding the powder directly to the soap batter. You can get a much darker color if you add the powder to the lye-solution and the warm liquid helps the color to become a kind of blue tea. That can help more of the color to be expressed in the final soap.

Soap Recipes with Natural Colorants

• Butterfly Pea Flower Soap Recipe (baby blue)
• Indigo Soap Recipe (blue shades)
• Himalayan Rhubarb Soap Recipe (magenta-pink)