Woad Soap Recipe: Naturally Coloring Soap Blue
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.
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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.
Woad Isatis 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)
Woad Soap Recipe
- Stainless steel pan for melting the solid oils
- A large bowl for measuring the liquid oils into
- 64 g Sodium hydroxide 2.26 oz
- 120 g Distilled water 4.23 oz
- 4 g Woad 1 tsp
- 145 g Coconut oil (refined) 5.11 oz
- 55 g Shea butter 1.94 oz
- 225 g Olive oil 7.94 oz | use light-colored or pomace olive oil
- 30 g Castor oil 1.06 oz
Add after Trace
- 1 tsp Lavender essential oil Optional
- 2 tsp Cedarwood essential oil Optional
- Soap making is fun and creative but it's also chemistry. Make sure your workspace is set up with your pre-measured ingredients and that you're wearing appropriate clothing, footwear, and safety gear. Always wear goggles and rubber gloves when handling lye or the soap batter.
- Dissolve the lye (Sodium hydroxide) crystals in the water. In an airy place pour the lye crystals into the water and stir well. I prefer doing this step outdoors when possible because of the steam that will come off it initially. It's not pleasant if you accidentally breathe it in so avoid this by holding the jug well away from you.
- When fully mixed, add the woad powder to the lye solution and stir well. Leave the lye-solution to cool in a safe place. I usually set the jug in cool water that I've run in the sink. Ensure that children and animals cannot get into it and be careful around it yourself. Never handle it without your gloves and goggles one.
- Melt the solid oils in a stainless steel pan on very low heat. When melted, remove from the heat and set on a potholder. Pour in the liquid oils and stir.
- Measure the temperatures of the lye-water and the oils. You should aim to cool them both to be about 100°F / 38°C. You don't need to be on the dot but aim to have them at that temperature or slightly cooler. The oils and the lye solution should be within ten degrees of one of another.
- While you're balancing the temperatures of the oil and lye solution, pre-heat the oven to 100°F / 38°C. I find that if I put it on at the lowest setting, this takes only a minute or two. Turn the oven off after and keep the door closed.
- When your ingredients are the right temperature, put your gloves and goggles back on if you've taken them off. Pour the lye solution into the pan of oils.
- Dip your immersion blender into the pan and with it turned off, stir the mixture. Next, bring it to the center of the pan and with both your hands, press it to the bottom of the pan and blitz it for just a couple seconds. Turn it off and stir the soap batter, using the blender as a spoon. Repeat until the mixture thickens up to 'Trace'. This is when the batter leaves distinguishable trails on the surface. The consistency will be like thin custard at first but it will thicken quickly so make sure to work quickly after this point.
- Next, add the essential oil and gently stir it in. It's for fragrance and completely optional. You could use other scents as well but make sure to follow the rules outlined in this piece.
- Lay your soap mold(s) out on a baking tray lined with baking paper. Next, pour the soap into the molds. Give them a tap or jiggle to settle the surface. Pop the molds with the tray in the oven and leave them there for a full day. Don't be tempted to open the oven during that time since heat will be lost. That initial warmth that gradually fades away is important to achieve a deep color.
- The next day, pop your bars from the mold(s), cut them into bars if required, and cure them for four weeks. Curing means leaving the bars spaced out on a protected surface out of direct sunlight and in an airy place. This allows the extra water content to fully evaporate out. It also allows the bars to harden up.
- Once made, your soap will have a shelf-life of up to two years. Check the oil bottles that you're using though — the closest best-by date is the best-by date of your soap.
Thank you so much Tanya for sharing! I love all of your videos and tutorials. I’m just curious as to why I could not put the woad in the oils and not the lye? Wouldn’t it maintain it’s color better not being compromised by the lye in it’s most active state? Would love to hear your insights! With gratitude. :-)
Hi Lydia, the lye doesn’t compromise the woad and is an easy way to add powdered ingredients that might form into lumps. It’s also a preferred way to add clay too and helps keep a nice consistent color through your bars.
Planning to start slowly change on homemade cosmetics, this soap and recipe look convincing. Just I hope I can find this plant :)
Thank you for sharing
A word of caution. Woad is considered an invasive, noxious weed in some parts of the world. Definitely is the case in the US western states. Please check before deliberately planting woad in your area! By all means, though, pick and utilize for home crafting.
Tanya, naturally coloring soaps is a brilliant idea! I’m going to read over all your posts in this series because I have some goat milk in the freezer waiting to become soap. Thank you for the idea!
Have you ever tried mixing woad and madder to form purple?
I haven’t but I’m not convinced enough that it would be a nice colour to try. If you do try and have success please share though!
Hi Leigh – Thanks so much :) There are a few people out there who colour their soaps with natural dyes, though extracts of alkanet and madder seem to be a bit more popular (and easier) than using woad. If you ever try your hand at soap-making again let me know how you get on! In chatting with the folks at Woad-inc.co.uk it seems that the (woad and madder) dyes they sell for fibre colouring aren't safe to use in cosmetics. So maybe have a look around for pure plant extracts if you decide on some experiments.
This is absolutely brilliant. Being a handspinner, I've dyed with these and other natural dyes numerous times, but always on fiber. I used to make soap (eons ago) and never dreamed of coloring them with natural dyes! As I said, absolutely brilliant.
Mr H. – I had to look that one up but know exactly which plant you mean – It's mainly referred to here as Mahonia and is used in herbal medicine. It's effective in the treatment of skin conditions such as acne and even psoriasis…very cool that it also can be used as a dye!
I know the method of making lye from wood ash but it results in a slightly different lye called Potassium Hydroxide opposed to Sodium Hydroxide which I use. I like to make solid soap bars and the lye you get from wood ash is only good for making liquid or slushy textured soaps. Would be an interesting exercise to try though!
Jo – Thank you :) I chose the mould since the triple-spiral is the ancient symbol of the island I live on. It's kind of evolved into a medieval three legged thing now but originally was a type of trinity meaning sea, sky and earth.
I'm glad you brought these to my attention, both plants are hardy enough to grow in my climate. The extracted colors are fascinating.
We have a plant that grows around here called Oregon Grape whose stems and roots yield a yellow dye, we once used it to dye curtains, not sure if it would work in a soap mixture.
Lovely soaps in the above picture. Have you ever made your own lye using wood ash?
It's amazing how plants give a different dye colour to what you would think. Your soaps are so pretty, I love the moulds you've used.
Sue – Thank you :)
Christine – Woad is a wild plant in most of Britain so definitely harvest it if you can find it! It doesn't seem to grow on the IoM though so I sadly would have to grow it like a garden plant. Lucky you!
Thank you for this post Tanya it was very interesting. Looking at the photo of Woad, I'm almost certain there is lots of that growing wild a hundred yards from my gate. I shall have to investigate.
Elaine – LOL!! Wouldn't that be handy after Christmas? Alas, my soaps are all vegetarian ;)
I really admire the fact that you go to all this trouble making soap. Have you ever seen the film 'Fight Club' he makes his own soap using the fat taken out from liposuction operations. Not something you indulge in I hope.
Caro – Thanks for the tips and am really interested in how you make homemade play-doh! That sounds fun :) I know about most of your natural colours already but most of them are unfortunately unsuitable for soap making. Due to the high heat and the chemical process between oils and lye, most natural colours morph. For example, beetroot and blueberry juice turn a horrible brown. Tumeric can be used but if you use too much of it your soap (any your skin) smells like it as well! lol I've never tried red cabbage but have heard it can also give a nice blue colour to soap. Thanks for the reminder of that!
Pat – You think you know what's in a product by the label and in so many cases the true processes and ingredients aren't listed! Take fragrance oils for instance – their ingredients are actually patented and secret so can't actually be displayed. Or processed chicken that's washed in ammonia to kill off bacteria – I'll bet no one's ever seen that on a label before either. The world of processed goods is a scary one!
Melissa – Thanks so much :)
Dani – So many fun things to make, so little time! My pinterest is going mad with all the project ideas I'm picking up myself ;)
What a fascinating post Tanya. I have never tried anything like this but I find it interesting that even soaps labelled as ;pure' may have chemicals in them. The farmer has quite a sensitive skin so he has to be careful what he uses for showering.
LOL – now I have to find out if woad and madder seeds are available here… :)
Love the colours of your soap!
Those are amazing!! :)
A very creative friend grows woad on her allotment and gave me some seeds. I've yet to grow them as I'm not sure what I would do with the plants! Other natural dyes that work on playdough (so I'm not sure if they'd be strong enough for soap) are red cabbage (turns blue, turn it back to fuschia pink with lemon juice), beetroot, blueberries, turmeric, etc.