What Is Castile Soap

What is castile soap?

What Is Castile Soap? The first thing that comes to mind is the soap that made by a certain doctors brand. But the short answer is that it is an olive oil-based soap, that can be either solid or liquid. The name came from the method used in the region Castille Spain. A true castile soap uses only olive oil soap. However, people found that using only olive oil made a soap that was too slick and did not clean as well as a traditional soap. So other oils are added to change the soaps function. Also, potassium hydroxide is used instead of sodium hydroxide. Potassium hydroxide doesn’t make the oils into a hard opaque bar like the sodium hydroxide. Rather it makes an almost transparent paste.

Oils that can be used to make castile soap

As long as you use olive oil and follow the soaping method, can it be considered a castile soap. However, as mentioned above, Using only olive oil will make a conditioning soap, yet it won’t clean as well as other soaps. So here are some examples of oils and what characteristics they bring to the table.

Coconut oil: Great for cleaning, however too much can be drying and a bit harsh.

Hemp oil: Nourishing

Castor oil: great for lather

Palm oil: great for cleaning

Apricot Oil: light nourishing oil

Castile Soap Recipe

Try this recipe for a mild liquid castile soap. Keep in mind this recipe makes a concentrated paste that you will need to dilute, add scent, and preserve later. Also, you might need to balance the PH with citric acid.

  • 37% Coconut Oil
  • 12% Olive Oil
  • 1.5% Apricot Oil
  • .5% Castor Oil
  • 13% Potassium Hydroxide
  • 36% Water


what is castile soap and how does it differ from cold process soap? First, it is the method. You will need a slow cooker to cook this soap over a long period of time. You will also need a stick blender, however, you will only need it for a little while. And for a majority of the soap making, you will need a strong spoon. You will be stirring a thick paste every 30 minutes. So you don’t want to burn the motor out on your stick blender.

Use heavy duty gloves, goggles, and protective clothing when making this soap. Treat it the same as you would if you were making cold process soap.


  1. Turn on your slow cooker and add all of your measured oils.
  2. Add your weighed potassium hydroxide into your measured out water. Remember to add the potassium hydroxide into the water. NEVER add water to the potassium hydroxide! It will cause a volcanic eruption of caustic chemicals! 
  3. Once the potassium hydroxide is dissolved in the water slowly add the mixture to the slow cooker with your heated oils.
  4. Stick blend the oils until they come to a thick trace. As soon as you feel resistance in the blender, turn off the blender, and grab your strong spoon.
  5. Mix the soap with a spoon until it is thick and looks like very lumpy mashed potatoes.
  6. Cover the slow cooker and let it cook on low.
  7. Stir and fold the mixture until every 30 minutes or so until it becomes an almost transparent paste.
  8. Once it is almost transparent, take a small amount and add it to a cup of hot water and dissolve the glob. If the water is cloudy, let it cook for longer. Once the water is clear, turn off the heat.
  9. When your soap is completely cooked (water is no longer cloudy) put it away in glass jars until you are ready to dilute into a liquid soap.

Castile Soaps Cousin

If this recipe is too complicated, and you want a ready to go pre-diluted soap. Look no further, Check out our Coconut Oil Liquid Soap Base. It is coconut oil that has been saponified with potassium hydroxide, the same way in the recipe above. And It comes pre-diluted and ready to be used. Just like that big name brand that many people use. However, this base can be customized in so many ways. Add your own fragrance or essential oils. Use this base to make a cleansing scrub. And so much more.





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