Use golden calendula flower petals to make natural yellow soap using the cold-process method. This calendula-infused oil soap recipe uses calendula petals infused in olive oil and a few other natural soap ingredients.
Years ago, when I first started making handmade soap, there were very few natural soap colorants around. In fact, I remember browsing the listings for a local soap ingredients supplier and the only thing even close were a handful of clays and the nature-identical (but not natural) ultramarines and oxides. It was then that I started experimenting with using plants and flowers from the garden to see what colors I could get. This calendula-infused oil soap recipe is the successful result of one of those experiments.
Calendula flowers are edible, a natural dye plant, have skin-healing properties, and are extremely easy to grow. For soapmakers, they’re a rare flower that doesn’t fade in color in the alkaline pH of soap. That means that we can use the petals in various ways to add cheerful yellow to orange color to our soap recipes. The recipe that you’ll find below uses calendula-infused oil, and instructions on how to make natural yellow soap. Steep the flowers for longer, or use a pure olive oil soap recipe, and you could even get an orange color.
Natural Yellow Soap Colorant
In my quest to discover ways to naturally color soap I’ve come across some beautiful shades. I’ve them listed in charts organized by color in this piece on natural soap colorants. Some are truly special, such as the vibrant magenta-red from Himalayan rhubarb, or the soft blue of indigo. Yellow soap colorants are some of the most common (just like in fiber dyeing) but calendula is my favorite.
Ingredients used to color soap are considered soap additives and they are completely optional to soap recipes. They also have different methods of use, and can be used as techniques to color most any soap recipe rather than just one. I’ve based this calendula-infused oil soap recipe on this one because it produces an eco-friendly and pure white bar of soap. You get to see a true reflection of the color that way, since the calendula displays true on the white base. Feel free to use the calendula-infused oil step for other recipes though. Those with more olive oil, or yellow oils, like cocoa butter, could intensify the shade.
Use Orange Flowers to make Calendula-infused Soap
One of the most important aspects of this calendula-infused oil soap recipe is choosing the right calendula. If you buy dried calendula, you’re often sent yellow flowers and no information on which type of calendula it is. If you grow it instead, which I highly recommend, you can choose to grow an orange variety. It’s important that you use orange flowers if you want to get a vibrant color.
Calendula officinalis, also called pot marigolds, come in several hues including yellow, orange, and pink. They are not related to the common marigolds (Tagetes types) that many people are more familiar with. Any orange variety will do for this soap recipe including the common ‘Indian Prince’ and ‘Orange’ or the less common Erfurter Orangefarbige, the type that I grow.
The color of the petals will translate into the shade you get in calendula-infused oil soap. The paler the shade of the flowers, the paler the shade of the soap.
Making Calendula-Infused Oil
The soap recipe and instructions below are beginner-level. It’s a basic soap recipe, with simple instructions, and a straightforward process. There are a couple of things that you should do to get the color right though. First is making the calendula-infused oil with the right flowers, as explained above. It takes about a month using the cold-infusion method, but there are quicker methods you can try too. Dried calendula flower petals are the safest way to make it too, since they won’t mold if they float to the surface. Fresh flowers will.
The brief instructions below give exact measurements for making calendula-infused oil. You don’t have to be as meticulous though. I used 25 g dried flowers to 500 g olive oil but you can use the folk method for making infused oil. Half-fill a pint jar with dried calendula flowers, then fill the jar up to the neck with olive oil. You can use any type of olive oil that you wish — extra virgin will give you a yellower soap though. If you wish to use the technique for another soap recipe, you can infuse the calendula flowers into other liquid carrier oils.
You can bottle any leftover calendula-infused oil and store it in a dark, cool cupboard for up to a year. Or until the best-by date of the oil or flowers you used. You can use it to make healing salves, in skincare, or even in food (providing you used dried flowers).
Calendula-Infused Oil Soap Recipe
The other thing that is important for getting a vibrant color is ensuring that your soap gels. Gelling is a heating action that takes place while your soap ingredients saponify. It only happens if the soap is kept warm and insulated though, or is oven-processed in some way. Though it doesn’t affect the cleansing or lathering properties of the soap it does affect color by deepening it. Gelling soap poured into loaf-molds is easier than gelling soap poured into individual cavity molds, which is why I use this mold for making calendula-infused oil soap.
There are other ways to use calendula in soapmaking too. Aside from using calendula-infused oil, you can also use the flowers directly in the soap. One of the easiest ways is to decorate the tops of the bars with dried flowers, but you can also mix the flowers into the soap batter too (see the photo at the bottom of this piece). You can also use a calendula tea in place of the distilled water in the lye solution, or all three techniques! But for now, let’s make calendula-infused oil soap to achieve buttery natural yellow soap bars.
Natural Yellow Calendula-Infused Oil Soap Recipe
- Stainless steel pan for melting the solid oils
- A large bowl for measuring the liquid oils into
- 25 g dried calendula flower heads or petals 0.88 oz
- 500 g Olive oil 17.6 oz
- 227 g Calendula-infused olive oil 8.02 oz
- 23 g Castor oil 0.8 oz
Make the calendula-infused oil
- A month before you make this calendula soap recipe, start infusing the olive oil with dried calendula flowers. Make sure that the petals are orange, not yellow. For this recipe, I used 25 g dried flowers to 500 g olive oil. You can eyeball it though if you wish as described further above.
- Mix the calendula and oil together in a sealed jar and leave them to steep in a dark but warm place for a month. Give the jar a shake every now and again.
- After a month, strain the flowers from the oil and discard (compost). You will have enough orange-tinted calendula oil to use for two batches of this soap recipe. Or you can use whatever you have left to make this salve.
- If you're in a hurry, check out these six ways to make infused oil for skincare. Some are quicker than others!
Prepare to make soap
- Prepare your workstation with your tools and equipment. Put on rubber gloves, eye protection, and an apron. Carefully pre-measure the ingredients. The solid oils into the pan, the liquid oils into a jug, the water into another heat-proof jug, and the lye in another container.
- Set out your mold and ensure you have everything you need laid out. Being organized at this stage will help you to successfully make soap!
Make the calendula soap
- The first step is to dissolve the lye (Sodium hydroxide) crystals in water. 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 breathe 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 potholder. Pour in the liquid oils. If you have the olive and castor oils in the same container, stir them together first before pouring into the pan. Castor oil is pretty sticky and it's easier to pour when mixed with a lighter oil.
- Measure the temperatures of the lye-water and the oils. You should aim to cool them both to be 100°F / 38°C, or just below.
- Pour the lye solution into the pan of oils. I recommend pouring the liquid through a sieve to catch any potential undissolved lye. The soap mix will still look somewhat transparent until you begin mixing it.
- 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 of 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 and look of it will be like thin custard.
- Stir in the essential oil, if you're using it. Mix thoroughly, but quickly. Essential oil adds scent to your soap but it's an optional ingredient and you can leave it out if you'd like unscented bars.
- Still working quickly, pour the soap into the mold(s). Give it a tap to settle it. If you wish, you can sprinkle dried calendula flower petals on top. If you live in a humid climate, don't do this, since any kind of botanicals in/on your soap can mold.
- Take steps to ensure that the soap gels. This is a process where the soap heats up and the color deepens and is important if you want bright colors. There are a couple of ways to do this but the best I've found is to place the mold in an oven that has been preheated to about 100°C (212°F). Turn the oven off and close the door. Leave the soap inside for at least 12 hours, or overnight.
- The next day, take the soap out of the oven and set it someplace to rest for another day.
- Once 48 hours have passed, you can take the soap out of the mold and cut it into bars using a soap cutter or kitchen knife. If you've opted to decorate the top with flower petals, cut the loaf from the bottom, to avoid dragging the petals through the soap with your knife.
- You can get five or six decent-sized bars of soap from this batch if you use the square mold that I have. In the six-cavity molds, you'll get six perfect bars, but it can be more challenging to gel the soap.
- Cure it for 28 days. 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. Here are full instructions on how to cure soap.
- 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.
More Calendula and Soap Inspiration
Calendula is, hands-down, my favourite skincare plant to work with. It’s easy to grow, looks beautiful in the garden, retains its color in soap and infused oil, and is incredibly healing. You’ll find quite a few recipes calling for calendula on Lovely Greens and I’ll pop a few down below. I also love the plant so much that I’ve even written an extensive ebook on how to grow and use calendula in soap and skincare.
- Calendula Skin Cream Recipe
- Natural Yellow Carrot Soap Recipe
- List of Natural Soap Colorants
- Calendula Healing Salve