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I love Castile soap.
And I love my DIY homemade Castile Soap even more. Why? Because I get to control what goes into it and the scents I choose.
For those of you who aren’t sure of what Castile is, it is soap made with olive oil as it’s base.
What is Castile soap?
Castile soap is a soap made with fats of purely vegetable origin, rather than animal fats such as tallow. This type of soap has historically been highly prized and viewed as a high-quality soap which is gentle on the skin and useful for a range of other applications. Many stores sell castile soap, and this soap is a specialty of several regions in Europe, where it is made with various traditional ingredients. It is also possible to purchase this type of soap base for the purpose of blending your own soaps.
This soap is said to be named for the Kingdom of Castile, a region in what is now known as Spain. Evidence seems to suggest this soap actually originated in Northern Italy, and spread outwards from there, although this soap is so ancient that it is a bit difficult to pin down the precise details of its history. In Castile, the soap was made with olive oil only, and some people differentiate between capitalized Castile soap, made with olive oil, and lower case castile soap, made with other vegetable oils.
Although olive oil is the traditional base oil, the soap can be made with coconut, hemp, avocado, almond, walnut, and many other vegetable oils. The composition of the soap will vary slightly, depending on which base oil is used. In pure form, the soap is white, hard, and odorless. Many soapmakers also make a liquid version, which is odorless and pale cream to white, often thickening in cool weather.
Uses and Background
Once the base is made, castile soap can be scented with various floral ingredients, blended with oatmeal and other coarse materials to assist with exfoliation, or treated in other ways to create soap with specific purposes. The soap is often used as a hand soap in fine hotels, and the soap can also be used as a general body soap, a shampoo, or a general cleaner. These soaps can be used to wash clothes, scrub floors, bathe pets, and in a variety of other situations when something needs to be cleaned.
This type of soap is often highly prized because it is made with natural ingredients, appealing to people who want to be environmentally conscious. It is also very gentle, suitable for people with sensitive skin along with delicate surfaces and fabrics ranging from soft stone to silk. Some people like to blend their own soap, using a base and essential oils.
Castile is the base of a lot of my homemade personal care products. I use a scented Castile soap for bathing, in my shampoo, and I even refill our hand soap dispensers using liquid Castile.
I make all of it at home so that I know exactly what is going onto my skin.
* 47 oz organic olive oil
* 32.9 oz. distilled water
* 9.39 oz KOH (potassium hydroxide) AKA Lye
* (Later at dilution) 80 oz of distilled water
(all pots, spoons, bowls etc. make sure they are stainless steel and/or heat safe)
(one that you will only use for soap, do not use again for food)
* Accurate scale
* Stick blender, immersion blender
* Large stainless steel pot
* Containers to store your soap
* Notepad and pen
Make sure you can set aside enough time during the day to give attention to your project without any distractions, have all of your materials ready to go, and ingredients already measured in safe and covered containers.
You will be working with lye and an immersion blender so, I recommend that you wear long sleeves, a hat, gloves, and goggles during the complete process. (I don’t, but that’s because I’ve been doing this for years and I am very familiar with my equipment.) Please make sure to keep your children and pets away from your work area.
Want more information about lye and proper handling? Make sure to visit our post all about lye here.
Start with 47 oz of olive oil in your CrockPot with the setting on LOW.
In a stainless steel pot, fill with the 32.9 oz of distilled water and place it on a heat safe surface. Get ready to pour the 9.39 oz lye into the water. Important: pour the lye into the water, DO NOT pour the water into the lye!
Pour very slowly and be careful that you do not splash the mixture around or breathe in any of the fumes that begin to rise up.
I personally do this outside so I have very good ventilation to avoid inhaling any of it.
Use your immersion blender to stir, stir, and keep on stirring. This is where you put all the work into it. Don’t give up and be careful of splashing. Do NOT run your immersion blender continuously. A friend (ok, ok, it was me!) made this mistake and burned up the motor in her blender midway through, ruining the entire batch of soap. I personally run the blender to a count of 30, then let it rest to a count of 10, and repeat until I reach trace. It saves both the blender and the soap.
In approximately an hour and a half, you should have thickened to a consistency that seems to “trace” the path of your blender. Once your soap is at this point is when we let it sit and cook. Put a lid on it and once every 20 minutes slowly stir it back up.
Use your heat safe spoon after this point. The mixture will be thickening. Using your blender at this point will only add more oxygen and cause the soap to fluff up, which is wonderful for Ivory soap, but we aren’t going for that cheap, marshmallowy soap.
You want to get it to the point where it is translucent and thick. This may take a couple of hours of checking on it. It’s not an exact science on how often to look at it. Remember to stir every 20 minutes and you will know when it’s ready.
To test your base, pour 1 cup of hot water into a clear glass. Stir in a small sample of your paste. (Make sure this glass goes into your soap-making kit so that you don’t use it in the future to drink from.) If you can still see through your glass then it is ready otherwise, wait and let the lye create the soap.
Return the soap paste to your large stainless steel pot after you have tested it.
Add a total of 80 oz of hot/boiling water on top of the paste. Gently stir the water in (just a little bit). Cover the pot and let it sit overnight. Your soap should slowly dissolve in the water.
(If you want to add any essential oils, this is when you would do so. I recommend 5- 10 mL of pure, therapeutic grade essential oils like doTerra.)
Your homemade liquid soap should be ready for you when you wake up in the morning. If you want to make sure that the soap is fully cured and the lye is no longer active, wait 3-4 weeks before using. I personally believe that cooking neutralizes the lye, making it no longer caustic, but better safe than sorry.
This is only a basic liquid castile soap and it is a great place to start. From here you can experiment with scents, oils, dilution etc…