Made using only olive oil, pure Castile soap is a mild, conditioning soap that is gentle enough to use on face and body.
Several years ago, I showed you how to make an easy, beginner soap. It was a recipe for a modified Castile soap. I could have labelled it as either a Marseille soap or Castile soap, but I decided to just call it an easy soap for beginners.
Why do I call that soap a modified Castile soap, while this one is a pure Castile soap?
First you have to understand what Castile soap really is.
The origin of Castile soap
While people have been making soap for thousands of years now, there’s a bit of a debate about the beginnings of castile soap.
It is thought that the first castile soaps were actually made with both olive oil and laurel berry oil in the Middle East. Those soaps are now known as Aleppo soaps.
When they began making a similar soap in the region of what is now Spain, they didn’t have access to the laurel berry oil, so they made a soap using only olive oil. (This soap completely differed from the soaps made in northern Europe using animal fats).
The term Castile soap comes from the kingdom of Castilla of Spain. At one time to be considered a Castile soap, the soap had to be made with olive oil from Castilla. It was a designation of origin just like “Champagne,” “Roquefort,” or “Kalamata olives.”
Over the years, though, it appears that the “Castile soap” term didn’t stick as an official designation of origin. Since then, the terminology has broadened to include soaps made anywhere geographically, and can be made from a combination of vegetable oils which normally, but not always, include olive oil as one of the main ingredients.
Marseille Soap vs. Castile soap
In France, they began to make a similar soap, Marseille soap. It also began as a soap made with 100% olive oil, but with time also began to included other vegetable oils. They began to add coconut oil to help harden the soap and make it a better cleaner. (Nowadays palm oil is another popular addition.)
Interestingly enough, here in Spain I see Marseille soap, or “jabón de Marsella,” for sale more often than “jabón de Castilla,” even though by now they are probably one in the same. (By that, I mean that you could formulate a vegetable oil soap with olive oil in it and get away with calling it either Marseille soap or Castile soap.) That’s why I say that my beginner soap recipe could be called either a Marseille or Castile soap.
Marseille soap is normally sold here for cleaning. It’s used as a bar soap for removing laundry stains, and is added to other household cleaners. It’s normally a soap made with olive oil, coconut oil, and sometimes palm oil. Coconut oil in soap makes a great cleaner, but can be drying to skin. That’s why I made my laundry soap recipe with 100% coconut oil.
I think that here, most people think of Marseille soap as being a soap made of mainly olive oil and coconut oil which is mostly meant for cleaning. On the other hand, they think of Castile soap as being a milder soap made with only olive oil and meant for face and body.
What is pure Castile soap?
Pure Castile soap, then, is soap made exclusively with olive oil.
Most modern “Castile soaps” for sale aren’t really pure Castile soaps. Despite the name, I don’t consider Dr. Bronner’s “Pure Castile soap,” to be a pure Castile soap at all. In fact, all of the Dr. Bronner’s soaps I’ve studied actually use more coconut oil than olive oil in their formulation.
I would like to say that I don’t think that using more coconut oil than olive oil makes for an inferior soap. In fact, I make and use more of my coconut oil liquid soap than I make and use my pure liquid castile soap. I think their soaps are great, but don’t think they should be labelled as they are.
Watch me make this Pure Castile Soap Recipe
Why make a pure Castile soap?
Olive oil is one of the few oils that can make a great bar of soap when used as 100% of the oils of the recipe.
It makes a very mild soap that won’t strip the skin of its natural oils in the same way that soaps with more “cleansing” oils, like coconut oil, can. That’s why they usually say that olive oil makes a very conditioning bar of soap, great for face and body.
While soap made with olive oil starts off soft, with time it can harden into a very hard bar of soap. It also improves with time, giving a bit more lather than in the first month or two after having made it. Some people like to cure their pure Castile soap for a full year before using it!
There are disadvantages to making a soap with 100% olive oil.
Pure Castile soap made with 100% olive oil feels “slimy” to some people. It doesn’t give that same “squeaky clean” feeling that some people hope for in a soap. (That is, of course, because it is a more conditioning type soap rather than a high cleansing soap.) Other people much prefer using pure Castile soap on their face and body, though, especially those with dry skin or skin conditions such as eczema.
Soaps made exclusively with olive oil don’t usually give as much lather, either, as soaps with coconut oil or other more lather producing oils.
Lastly, the curing time for pure Castile soap tends to be longer than for other soaps. It needs more time to fully harden and give a better lather.
The saponification process, the process in which all of the lye is converted into soap, actually finishes within the first few days. So, technically, you can begin to use the finished soap almost immediately, and don’t have to worry about residual lye. That said, over time, the soap will benefit from a curing time in which it will harden into a longer lasting soap. Other chemical processes continue within the soap over the next couple of weeks, too, which help improve it with time.
Pure Castile Soap Recipe
Pure Castile Soap
Materials
- 600 g olive oil
- 228 g water
- 77.2 g lye Sodium Hydroxide (NaOH)
- 18 g lavender essential oil Optional, for fragrance. Can use other EO’s or fragrance oils.
Instructions
- Protect your eyes and skin by wearing protective goggles and gloves.
- Weigh out the water in a medium sized bowl.
- Weigh the lye in a small bowl.
- In a well ventilated area, carefully pour the lye into the bowl of water. Do not do this the other way around, meaning DON’T pour the water into the bowl of lye.
- Carefully stir the lye and water until the lye has fully dissolved. It will begin cloudy, and it will get hot, but as you leave it to rest for several minutes, it will begin to clear up and cool down.
- Meanwhile, weigh the olive oil in a large bowl.
- Carefully pour the lye solution into the bowl with the olive oil.
- Mix gently at first to incorporate the lye mixture into the oil.
- Once combined, you can begin to blend the mixture with an immersion blender. This process will take several minutes.
- As you blend the soap mixture, you will notice that it begins to get thicker and more opaque. It will eventually thicken up into a consistency like a salad dressing. This point is called “trace.”
If you’ve made soap before, you’ll notice that it takes a bit longer for this soap to reach trace than soaps with some other oils. It also is a bit thinner than many other soaps when it reaches trace. You can pour it into molds a trace, but it will take a bit longer to thicken up. - Once you have reached trace, you can add in your fragrance oils. My favorite is lavender essential oil. Not only do I love its scent, but it tends to be longer lasting than some of the other essential oils when used in soaps.
- Pour the soap mixture into your mold(s). You can use silicone pans or molds, lined wood or cardboard boxes, or even plastic Tupperware type containers as molds if you don’t have a mold specifically made for soap.
- Set the soap aside and allow it to rest for several days. Pure Castile soap will take longer to harden than most other soaps. I think I unmolded mine (the one in the video) two days after having made it, but it was still very soft, almost like butter. I could have (should have) waited longer, but I wanted the mold for another soap. 🙂 In any case, while soft, you can fix some of the surface imperfections by smoothing it with a knife (like I show in the video).
- Wait longer for the soap to harden a little more before cutting the soap into bars (if you’ve used a large pan type mold). In the video, I think I had waited another 3-4 days. You’ll notice that the soap had a lot more solid consistency and was already lighter in color.
- Your soap is now finished, but will need to be left to dry out and cure for at least a month. This is a soap that really benefits from a long cure time. Some people even wait a year before using their pure Castile soap!
Notes
- When I finished making my pure Castile soap, it looked a lot like butter. In fact, a friend came over and saw it sitting on my kitchen counter the day after I unmolded it and asked, “So you’re making butter now?”
- With time, it has gotten a lot harder and a lot whiter. I was actually quite surprised as to how white this soap turned out considering that I had made it with a pretty dark colored extra virgin olive oil.
Other Notes:
You can see in the video that I have always used heat resistant glass bowls for mixing the lye solution. It has since been brought to my attention that the heat from the sudden rise in temperature can cause glass to break, so it’s recommended by many people that you not use glass bowls for mixing the lye solution. While I have never had any issues, even after years of making soap this way, I’d like to call attention to the possibility to help keep you safe!
That’s why I’d like to say that the ideal container for mixing the lye solution is probably stainless steel. While some plastics (#5, for example) are fine for mixing lye, others can’t handle the alkalinity (lye solution can eat a hole through #1 plastic). I prefer to avoid plastic, personally. You should also avoid using other metals as many can also react with the lye.
Mikala
Can I use fresh lavender crushed instead of essential oils?
Tracy Ariza
Hi Mikala,
While you could, lavender turns brown in soap and makes for a not-so-beautiful addition. If you don’t have a problem with that, though, give it a try!
adexhe
I just found your website and will try all your recipes ! Thank you !
Pam du Toit
Hi
Thank you for this wonderful information. I have been making pure castile bar soap for a while. However, my soap always has a thick layer of white soda ash. Some bars have more than others. The soap works fine but it is not a good look. Any suggestions about how to overcome this problem.
Thank you,
Regards
Pam
Tracy Ariza
Hi Pam,
While soda ash is really only a cosmetic issue, you can prevent it by applying alcohol (above 90%) to the top of your soap in the mold. If you spray and let it dry and then spray again, you form a bit of a protective coating on your soap.
You can also consider heating the oils when before mixing with the lye solution. That is also said to help prevent it.
Once you have the soda ash, you can usually rinse and scrape of off quite easily. Some people steam it or “shave” it off. 😉
Jerrell Slay
Awesome post! I was wanting to buy this soap product online but wasnt sure if its castile soap could you help me understand these ingrediants?
Saponified Olive Oil , Sunflower Oil, Aloe Vera, Shea Butter, Rosemary Extract, Coconut Oil, and Citric Acid.
Is this castile soap with added oils and extracts?
Thanks and love your website!!
Tracy Ariza
Hi Jerrell,
Yes, it appears that way.
Saponified olive oil is the olive oil that has already been reacted with lye. I’m having a hard time understanding why the other oils aren’t saponified, though.
I sort of doubt that they made a pure olive oil soap and then just added the other ingredients to it, especially since it has 2 other oils and a butter.
It’s more likely to me that the soap was made with a mixture of the 4 fats.
Ingredients on soap are often written in different ways, though, so it makes it difficult to know for sure.
Catherine
I made this recipe today! Thank you for the very easy to follow recipe and instructions. I’m a beginner and it’s much appreciated! I poured mine into individual face bar molds. What is the best way to set them to cure? I’m worried about the bottoms not getting enough air flow.
Tracy Ariza
Hi Catherine,
After they are hard enough to remove from the molds, do it. That will allow airflow.
Castile soaps benefit from a long cure time, so keep that in mind. I like to keep them standing up on one side to allow as much airflow as possible. For the first days, I also occasionally flip them over. I hope that helps.
Catherine Geremia
They came out beautifully! So creamy! Could I add activated charcoal to this recipe?
Tracy Ariza
Hi Catherine,
I’m so happy to hear it!
Yes! You can definitely add activated charcoal to it. I have a recipe for an activated charcoal facial soap that may give you an idea of a good amount to add. ?
Steve Wilson
I’m thinking of having a first try at this recipe. Will the lye really break down and be safe? I don’t want to get it wrong and burn myself and others.
Tracy Ariza
Hi Steve,
Yes! Do not worry!
especially in a cooked recipe like this one, all the lye is reacted by the time you are done cooking. (Even in cold process soaps, very little lye is left after mixing with the oils- as long as the recipe is calculated correctly- and within a couple of days none is left. Even if you were to use the soap immediately, though, the soap would only be a bit harsher and wouldn’t really burn you.)
I think you would really like my post about what is lye. It explains it all a lot better!
Suzanne
Hi I’m going to have a go at making this soap I just want to clarify with you the recipe says water but the video says distilled water. I assume you cannot use tap water?
Tracy Ariza
Hi Suzanne,
It’s not that you “can’t” use tap water. I actually used to use my filtered tap water without any issues.
The problem is that some water can have minerals or other chemicals in them that I just want to avoid. If something goes wrong with a recipe, I like to be able to rule out the water as the problem. So, I recommend distilled water (and also use it myself).
In most cases, it probably wouldn’t be an issue, but I’m trying to ensure people have success with the recipe as best I can. 😉
Juana
Thank you very much for this recipe, I was so excited when I make my first soap, my daughter and I went crazy using essential oils, I put lavender, argan and wormwood oils, they are so great,I am planning on doing more of your recipes, thank you again for this site. I love the soaps.
Tracy Ariza
Hi Juana,
Thank you so much. I really appreciate your comment, and am very happy that you enjoyed the soap! 🙂
Avery
Hello! Thank you for the detailed post! I have a couple of questions for you.
1. How so you go about washing the materials after you’re done? Specifically the bowls used for measuring and mixing the lye?
2. When the mix is hardening and still in the mold, does it need to be covered or is it better left in a ventilated area? And when cut into blocks should they be wrapped up? Kept in a warm or cooler room..?
Thank you!
Tracy Ariza
Hi Avery,
1) I really just wash most of the materials with water. They have soap residue so they clean well. You can add a bit of a different soap to make sure you’ve thoroughly cleansed. I do rinse and then wash the containers and whatever I used to mix the lye solution. I normally also run those through the dishwasher. Some people prefer to have specific materials and tools for making soap, but I don’t feel it’s necessary. Lye is also used in food preparation. It’s used to cure olives and can also be used to give a specific crust texture on certain pretzels and bagels. You have to be careful when you’re working with it, but some people are overly scared about it once they’ve rinsed their materials.
2) Some people cover it to insulate the soap if they want their soap to gel. (Someday I’ll have to write a post about it.) I don’t normally do that because I like the lighter color of ungelled soaps. People try to gel their soaps when working with certain colorants to get brighter colors and such.
I don’t wrap my soaps once I cut them. I just leave them with a bit of space between them to let them air out.
They may dry faster in a warmer room, but I’d chose a room without very much humidity. The temperature probably isn’t as big of a deal!
DJ
Thank you for the great recipe! Is it better to let the soap cure after it has been cut into blocks or should I let it cure for several months in one large block? Thanks!
Tracy Ariza
Hi DJ,
Let it harden for a couple of days- to give it enough consistency to cut, without falling apart. Then cut it and let it cure.
If you wait too long, it will be too difficult to cut- and your bars will most likely break. (It can get slightly brittle.)
Because this soap only uses olive oil, it tends to take a lot longer to set and get to a point where you can unmold and cut it. If you make a pure coconut oil soap, like my coconut laundry soap, it sets up in a matter of hours, and even if you wait until the next day to cut it, it can get too brittle to easily cut in bars!
This soap takes a bit more patience- and the soap itself also benefits from a really long curing time.
Mirai
Hi Tracy,
Thank you for this recipe and such thorough instructions! I’m planning on making a batch, my very first time trying to make soap, as cast gifts for a production of She Loves Me that I’m in (there is a lyric that goes “I would like a cake of castile soap…” over and over again!)
I’ve seen other recipes call specifically for distilled water, and yours doesn’t – does it need to be distilled? Does it matter? What do you usually use for your soaps?
Tracy Ariza
Hi Mirai,
I usually do use distilled water because you can be sure that you aren’t adding any impurities. That said, I used to always just make it with our filtered drinking water and never had any issues. I got so used to making everything with distilled water that I now also make bar soaps that way. It’s usually pretty inexpensive to buy. Here in Spain they sell it in big containers with the cleaning supplies because people usually use it in their irons. That said, I use so much that I ended up buying a water distiller.
I’d like to make a suggestion, though…
If you’re going to make a molded soap- and it’s for something relatively soon, I’d probably go with a mixed oil soap recipe. My beginner soap is a modified Castile soap that uses some coconut oil in it. (Consider the fact that Dr-. Bronner’s Castile soaps are mostly made using coconut oil!)
They harden faster, make harder bars in general, and give more foaming- a better lather.
Pure Castile soaps are a bit of an “acquired taste” and take a much longer time to cure to the point that some people are happy with them. I made it and like it OK, but I prefer a soap with a bit of coconut oil or animal fats.