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How is Castile Soap Made?

how is castile soap made

Castile soap ranks amongst the oldest known soaps, and its popularity is ever-growing because it’s versatile, inexpensive, gentle on skin, and eco-friendly. It derives its name from Castile, Spain, where olive oil is found in abundance and was used as the main ingredient in the original Castile soaps.

Basic Ingredients of Castile Soap

Making liquid Castile soap is an easy process, referred to as saponification – which means soap making (‘sapo’ is soap in Latin). 

Saponification is a process of combining base oils with an alkali, leading to a chemical reaction that yields liquid soap. The main ingredients are plant oils, potassium hydroxide (an alkaline solution, also called lye), and distilled water.

At Clean Rebellion, we use only organic products in our Castile soap which we put through a thorough saponification and purification process to create a lush, natural soap your skin will love.

Making Castile Soap: The Saponification Process

Olive oil comprises long-chain fatty acids that cause a moisturizing lather that’s gentle on your skin. That’s why we only use organic olive oil in our Clean Rebellion soaps! Plus, it turns out that the saponification process transforms coconut oil into a tough cleanser that isn’t as well suited for your skin.

Making olive-oil-based Castile soap is a simple process, but it must be done correctly to create a high-quality, effective product. 

We’re passionate about making the perfect soap—some even call us “soap nerds.” If you want to nerd out with us, here are the steps that go into the Castile soap-making process:

  1. As olive oil is heated, potassium hydroxide (also known as lye) is carefully combined into water until dissolved. (Note: precautions must be taken when handling lye, so be careful if you try to make DIY soap at home).
  2. The water-alkali mixture is heated into the melted oil and blended until creamy and thicker. Blending continues until the right consistency is achieved.
  3. The mixture then sits for a few hours, stirring it every 30 minutes so it cooks evenly and starts becoming translucent.
  4. Once it’s a translucent gel, the soap is tested for clarity. If it is cloudy, it is cooked longer until clarity is achieved.
  5. Once it remains translucent, it is diluted with hot distilled water until well combined.
  6. The mixture is then left to liquefy for 10 – 12 hours at room temperature before being transferred to its bottle.


At Clean Rebellion, our soaps are extra special because we’ve added affirmations to our bottles to add a boost of positivity to your daily routine, along with the benefits of our luxurious soaps.


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