Learn to make herbal soap with essential oils, mineral color, and dried herbs and flowers. Part of the Simple Soap Recipe series.
Herbal essential oils are varied and relatively inexpensive which makes them great for soap making. In this piece you’ll learn how to make herbal soap using rosemary and peppermint essential oils along with citrusy lemongrass. That combination of scent is visually illustrated with the scattering of calendula petals on an otherwise green soap. It’s a great combination that you’ll have fun both making and using.
Naturally scented soap is almost always made with essential oils. Concentrations of a plant’s volatile oils that are not only therapeutic but smell nice too. They’re the bottled life force of the plant and each has its own special properties. Rosemary oil is stimulating and aromatic and peppermint invigorates the mind and your skin. Lemongrass is a pleasing green yet citrus scent that gives this soap an uplifting note.
What’s in this recipe
Aside from the essential oils already mentioned, the other main ingredients are base oils, sodium hydroxide, and water. Making soap is creative but it’s also chemistry. Sodium hydroxide, called lye, breaks apart the oils used and then reforms it into a new compound that we know as soap. All soap is made this way, even melt-and-pour soap has been through this process before you begin working with it.
Each oil used will give your bars a different quality be it hardness, conditioning properties, or lather. I’ve also formulated the recipe to be palm-oil free, and to use a nature-identical mineral to tint the bars a pretty shade of green.
Make herbal soap with dried herbs
Although optional, I think that decorating soap with dried herbs and flowers makes it more attractive. It may not necessarily add therapeutic properties, at least not in the same way that essential oils, but it does add interest and sometimes exfoliation.
In this recipe I’ve added dried peppermint for visual effect and to match the essential oil used. One really fun thing about dried peppermint is that it will bleed into the soap over time. If you look around the peppermint in the image below you’ll see warm colored halos around the pieces. It’s a warm tone that matches the calendula flowers but you’ll only begin to see it during the curing process. If you wanted to, you could even add a pinch of dried peppermint to the entire soap batch. They’ll create a speckled effect similar to my peppermint soap.
How to make soap
Almost all of the recipes you’ll find on Lovely Greens are geared for the beginner to intermediate soap maker. That means that if you’re new to soap making you should be able to make herbal soap fairly easily. However, you’ll have a better understanding of what’s involved if you have a read through the Natural Soap Making for Beginners Series:
Soap Making Equipment
Much of the soap making equipment you need could already be in your kitchen. Rubber washing-up gloves, bowls, and even silicone molds. If you don’t have everything, you can purchase it online relatively inexpensively. Also make sure to check out second-hand shops for pots and other items.
To protect yourself from the lye-solution you should always wear eye protection (goggles) and rubber gloves. Here’s more of what you’ll need:
- Digital Thermometer gun
- Digital Kitchen Scale
- Stick (Immersion) Blender
- Stainless steel pan for melting the solid oils
- Heat-proof jug for the lye-solution
- A large bowl for measuring the liquid oils into
- Rubber spatula for stirring and scraping
- A small dish for mixing the color in
- Small sieve (strainer)
- Mixing color is a whizz with a milk frother
- A standard take-out container as a soap mold. Line it in baking/grease-proof paper
Now on to the recipe…
Herbal Soap Recipe with Rosemary & Peppermint
- 64 g Sodium hydroxide 2.27 oz
- 115 g Distilled water 4.06 oz
Add after Trace
- Dried peppermint leaves
- Dried calendula petals
- Pre-mix the Chromium green oxide in about a Tablespoon of the olive oil. Prepare your soap mold(s) now too. The one I'm using is a clean take-out container lined with two strips of baking paper. One laid lengthwise, and the other one across. Leaving overlapping paper will help you get the soap out when it's ready.
- Next, dissolve the lye (Sodium hydroxide) crystals in water. Gear up with eye protection, gloves, and wear a long sleeved top. In an airy place, outdoors is best, pour the lye crystals into the water and stir well. There will be a lot of heat and steam so be careful. Try not to breath it in. Leave outside in a safe place, or in a shallow basin of water to cool.
- Melt the solid oils in a stainless steel pan on very low heat. When melted, remove from the heat and set on a pot holder. Pour in the liquid oils including the colored oil.
- Measure the temperatures of the lye-water and the oils. You should aim to cool them both to be about 120°F / 49°C.
- Pour the lye-solution into the pan of oils. I tend to always pour the liquid through a sieve to catch any potential undissolved lye or bits.
- 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, hold it on 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 a distinguishable trail on the surface. The consistency will be like thin custard.
- With your spatula, stir in the essential oils. If you'd like a few calendula petals on the inside of the soap, stir in the optional 1/2 tsp of them now. Working quickly, pour the soap into the mold(s). Sprinkle the top with dried peppermint first then a few more calendula petals.
- Turn your oven on to very low and heat for just a minute or two until it's 100°F / 38°C. Then turn your oven off, and pop your soap mold(s) inside. Leave overnight. Oven-processing the soap like this intensifies the color.
- The next day, take the soap out of the oven and set someplace to rest for another day. Once 48 hours have passed, you can take the soap out of the mold(s). Cure it for 28 days before using. 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.
- 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.
Simple Soap Recipe Series
When learning to make handmade soap I’d highly recommend working with a single base recipe. That way you’ll know what to expect each time you make it, be able to spot any differences or issues quickly, and save money.
That’s why this herbal soap is part of the Simple Soap Recipe Series. Each of the recipes uses the same main base oils, water, and lye amount. They’re made unique by using different scents, color, and natural decoration. Aside from this recipe I’ve also shared a gorgeous citrus soap and two beautifully scented floral essential oil soap recipes.
- Zesty Citrus & Calendula soap recipe
- Lavender & Poppy seeds soap recipe
- Rose Geranium soap recipe
- Herbal soap recipe
- Read this introduction to Lovely Greens soap making for even more inspiration