Recipe and instructions for how to make natural lavender soap. Includes tips on using lavender flowers, natural purple colorants, & light exfoliants
Over the years I’ve created and shared recipes for various types of lavender soap. Some of them include a blend of essential oils, others have added exfoliants, flowers, or natural colors. The lavender soap recipe I share in this piece is pure and simple but can be customized if you’d like to add more flair.
That’s the beauty of making your own natural soap. Once you have the basic principles and technique down, you can make as simple and as complex soap as you’d wish. Keep this in mind when you’re making this soap recipe. Stick to the basic ingredients or feel free to use the tips below to add additional natural ingredients.
Natural Soap Making for Beginners
2. Equipment & Safety
3. Basic Recipes and Formulating Your Own
4. The Soap Making Process: Make, Mould, and Cure
If you’re new to making handmade soap, you should check out my four-part series on natural soap making. It gives a good introduction to what to expect from ingredients, equipment, recipes, and how to combine everything together to make soap. It’s especially important to be careful when handling lye and part 2 below will tell you what to expect. Lye isn’t something to be scared about using but you should know how to handle it safely.
History of Lavender Soap
There’s no clear reference to say how and when soap was invented. As far as historians can tell, there were various methods of making crude soap-like substances from both the middle east and china. The earliest account is of a recipe written on a clay tablet from Babylon in 2800BC. It used “water, alkali, and cassia oil”. These first soaps were probably unscented since we first hear of fragranced toilet soap in the 9th century.
The production of fragranced soap was first recorded in the 9th century by Muhammad ibn Zakariya al-Razi of Persia. A celebrated alchemist, philosopher, and considered the greatest physician of the Muslim world, al-Razi left in his legacy the first soap making recipes. Though I can’t find a reference, I strongly suspect that lavender had a part to play in scenting these very first bars.
Soap making in the middle east continues with soap factories in Syria around the same time. This Aleppo soap was imported into Europe and was then adapted there to make Castile soap — soap made with olive oil. Though Aleppo soap is traditionally unscented, it’s probable that scented soap was introduced to Europe at the same time.
Types of Lavender essential oil
Lavender soap is generally understood to be soap that smells like lavender. The real deal is always made with lavender essential oil, the distilled oil from lavender flowers. It’s deeply fragrant and has more beneficial properties to mind and body than I can list here. If you’d like to learn more about the benefits and history of lavender oil, how it’s extracted, and how to grow lavender, I have an in-depth piece that you can read here.
When sourcing your own lavender oil for recipes be aware that there are two main types of essential oil. Lavender flower oil, labeled Lavandula angustifolia (Lavender) flower oil, is the more common and it has a density of 0.885 g/ml. The second type is distilled from a similar plant called Lavandula latifolia and has a density of 0.905g/ml. It’s more commonly known as Lavender Spike oil. The measurements come into play when you’re working out how much to use in your recipes.
How much lavender essential oil to use
In wash-off skin products like soap, you should use a maximum of 3% lavender essential oil by weight. This guideline was set down by the European Union and is there to protect us against skin reactions. Lavender essential oil, like all essential oils, is not ‘pure lavender’. It’s a complex mixture of natural phytochemicals including linalool and linalyl acetate. Some people can have severe reactions to these components which is why you shouldn’t exceed this a 3% usage.
For a 1 lb (454g) batch, like the one I share below, you should use no more than 13.62g of lavender essential oil. Lavender flower oil has a density of 0.885g/ml so that works out to 15.39 ml of essential oil for a one-pound batch, or about 3 teaspoons (3.12 tsp to be exact).
Lavender spike oil on the other hand has a different density of 0.905g/ml. That means that for a 1 lb recipe you’d need 15.05ml or 3.05 tsp. It’s not a huge difference for small batches which is why I feel comfortable recommending using teaspoons or either type of lavender oil for this recipe.
If you make a whopping big batch of this though, say a 7200g (15.87lb) batch then the difference between the two is clearer. You’d use 48 tsp of lavender flower oil or 49.5 tsp of lavender spike oil. More information on calculating essential oil amounts for soap recipes.
Naturally coloring soap purple
The natural color of soap is first dependent on the main soaping oils. Extra virgin olive oil will give you a greenish tinted soap which is why a lot of soap makers will use lighter-colored Pomace olive oil. That way they can have more control over tinting soap to the desired color. Just remember that the color of your main soaping oils will affect the final color of your soap. This is regardless of whether you use additional colorants or now.
For a traditional lavender soap recipe you wouldn’t tint the soap at all. The natural color of olive oil soap is understated and beautiful in its simplicity. If you’d like to match the lavender scent of your soap to a color there are various ingredients you can use.
Alkanet, Ultramarine violet, and Gromwell root all come to mind. Alkanet and gromwell are plant roots that you can use to either infuse some or all of your soaping oils with. You can also add the powder directly to soap but it may give your soap a gritty feeling.
Ultramarine violet is a nature-identical mineral powder that’s probably the easiest of the three to use. There is discussion over whether it can be considered ‘Natural’ since it’s recreated in a controlled environment. I have a hard time working out why folks are so up at arms over it. After all, the lye that is used in all-natural soap recipes is made in a controlled environment too. See even more ingredients that can be used to naturally color soap.
Using lavender flowers in soap
There’s one major issue in using lavender flowers and buds in soap — they have a tendency to turn brown. Mix them into your soap before it’s hardened and saponified and they will definitely turn brown. Sprinkle them on top and they’ll probably brown. There are two tricks to stopping this from happening though.
First of all, lightly press lavender stems into your soap about five minutes after you pour it. Make sure that only the bottom edge is actually touching the soap as shown in the photo above. Make sure that you don’t insulate the bars either since heat will brown them.
The other method to stop lavender from turning brown on soap is even more clever. Allow your bars to fully saponify for 48 hours. Then spray the tops with alcohol, sprinkle lavender buds on top and spray them again. The alcohol will make the lavender stick.
Over time lavender will naturally brown but it will take weeks or even months. Using these tips will ensure that it’s not instant or overnight browning though.
Natural exfoliants for lavender soap
Another way that you can customize lavender soap is by adding natural exfoliants. Oatmeal, poppy seeds, and fine pumice are all great choices and add visual interest too. Each of these would generally be added at ‘Trace’. The amounts that you can use vary but this is what I’d recommend:
- Oatmeal: use up to 1 Tablespoon (5.5g) per pound of soaping oils
- Poppy seeds: use up to 1/2 tsp (1.5g) per pound of soaping oils
- Fine Pumice: use up to 1/2 tsp (3g) per pound of soaping oils. I recommend that you pre-mix it with a little oil before adding it to avoid clumping
Natural Lavender Soap Recipe
- 64 g Sodium hydroxide 2.25 oz
- 115 g Water (preferably distilled) 4.05 oz
Ingredients to add after Trace
- I always advise to get everything prepared and measured before starting to make soap. Get your equipment set out, measure out all the ingredients -- this includes the water into the heat-proof jug, lye into a jar, and solid oils into the pan.Your liquid oils should be in a kitchen bowl or jug. Once they're measured, pour about a Tablespoon out and into a small jar. Into this small amount of oil mix the Ultramarine violet if you're choosing to use it. One of those mini milk frothers is very helpful but you can use a tiny wisk or fork as well. It's optional but will give you a lovely lavender shade. Without the mineral your bars will be a creamy and natural colour.You should also be wearing closed toe shoes, a long sleeve shirt, hair pulled back, and wearing eye protection and rubber/latex/vinyl gloves.
Mix the Lye Water
- Soap making is chemistry so this step needs particular care. Double checking that you're wearing eye protection and rubber gloves, pour the lye crystals into the water in a well ventilated place. Outdoors is best as there will be steam and heat when you mix them together.Stir immediately and thoroughly with a silicone spatula until you're sure all the lye crystals are completely dissolved. Allow to cool outside or place the jug in a basin of water to help it cool down. If I'm cooling lye-water indoors then I fill the sink with an inch of water and put the jug in to cool.
Melt the Solid oils
- Just after you mix the lye water, place the pan of oils on low heat. Stir while it's melting to speed things up. When there are just a few small pieces that are unmelted, take the pan off the heat and continue stirring on the side.When fully melted, pour the liquid oils into the pan -- meaning the sunflower oil and olive oil. Save the essential oil for later.Also add the coloured oil. Pour it through the sieve and into the pan. Ultramarine violet has a tendency to clump in my opinion so that sieve will catch any lumps. If they make it into your soap you'll have lumps of colour in your bars.
Melt the shea butter
- Before you head to the next step you need to melt the shea butter. It's added at 'Trace' so that it stays in your soap as rich butter rather than being transformed into soap. You can melt it either in a microwave on short bursts or using a double-boiler.
Taking the temperature
- When making this recipe, you want to aim for getting your pan of oil and lye water to around 120°F / 49°C. They don't need to be bang on but should be around that mark and both the oils and the lye water should be within ten degrees of one another.
- When the temperatures are just right, pour the lye water into the pan of oils through a sieve. It will catch any bits of undissolved lye. Now stick blend. I’ve included a video in this piece for another soap recipe (my lemongrass soap) and it shows my technique for stick blending. Have a watch to see what to look for and what 'Trace' means. It's basically when the mixture begins to thicken up and has the consistency of custard.
Essential oils & molding
- When you’ve hit the right consistency, add the melted shea butter and essential oil. Stir quickly but thoroughly since it may firm up fast. Next pour the batter into the molds, using that spatula to get every last drizzle of soap.
- Leave it in the mould for 48 hours. After that point saponification is mostly complete and you can pop them out. Let the soap dry out for four weeks before using. This process is called ‘Curing’ and I have a great piece on what to do over here.