Is There Lye in Natural Soap?

If you've ever looked into natural soap or considered making it yourself, you've likely encountered a recurring question: is there lye in natural soap? The answer is yes and no— depending on which stage of soap making you are asking ;) let’s dive into the chemistry and history of soap to understand why. 

The Chemistry of Soap

At its core, soap is the result of a chemical reaction called saponification. This reaction occurs when fats or oils (such as olive oil, coconut oil, or animal fat) are mixed with a strong alkali. Historically, this alkali was derived from wood ash, but today we use a purified version: sodium hydroxide (commonly known as lye). [1]

During saponification, the lye interacts with the fats and oils, breaking them down into glycerin and soap salt molecules. By the end of the process, if done correctly, there is no lye remaining in the finished soap—only the nourishing glycerin and cleansing soap. Cascadia’s natural soaps are also "superfatted," meaning extra oils are added to ensure all the lye is fully consumed during the process, leaving behind a moisturizing, skin-loving bar. [7]

A Brief History of Soapmaking

Soapmaking has a fascinating history spanning thousands of years. The earliest evidence of soap dates back to ancient Babylon around 2800 BCE, where soap-like substances were made by boiling fats with ash [2]. In ancient Egypt, soap was used for cleansing and treating skin ailments [3]. The Romans refined soapmaking, and the word “soap” is thought to come from Mount Sapo, where animal fats mixed with ash created a cleansing substance [4].

During the Middle Ages, soapmaking became an artisan craft in places like Marseille, France, and Castile, Spain. These regions developed iconic soaps using olive oil. However, soap remained a luxury item until industrialization in the 19th century made it more accessible [5].

Natural Soap Today

Modern natural soapmakers embrace traditional techniques while incorporating high-quality ingredients. Unlike commercial soaps with synthetic detergents, natural soaps are made with oils, fats, and lye, just as they were centuries ago. Handcrafted soaps, like those at Cascadia Skincare, are created using the cold process method. This allows for slow saponification, retaining glycerin and creating a nourishing bar of soap. [6]

Why Understanding Lye Matters

The idea of using lye can sound intimidating, but it’s important to understand that all true soap is made using lye. Without lye, there’s no soap—only detergents or other cleansers. Skilled soapmakers calculate the exact amount of lye needed to fully react with the oils, ensuring no lye remains in the finished product. Superfatting adds extra oils, making the soap more moisturizing and gentle on the skin. [7]

Appreciating the Craft

*Cascadia's founder Joel Morassutti making our signature goat milk soap bars.

Natural soap is more than a cleansing product—it’s the result of centuries of tradition, chemistry, and artistry. By understanding the role of lye and the history of soapmaking, you can better appreciate the skill and care that goes into creating every bar. Cascadia’s superfatted natural soaps are a testament to this craft, offering gentle, skin-loving benefits in every use.

References

1. Cavitch, S. M. (1997). The Natural Soap Book: Making Herbal and Vegetable-Based Soaps.

2. Dunn, K. (2010). Scientific Soapmaking: The Chemistry of the Cold Process.

3. Smith, E. (2007). "The Egyptian Art of Soapmaking" in Ancient Skincare Rituals.

4. Historical Encyclopedia. "Roman Innovations in Soapmaking."

5. McGraw, J. (2019). The History of Handmade Soaps: From Luxury to Necessity.

6. National Soapmaking Association. "Cold Process Soap Benefits and Techniques."

7. Soap and Detergent Association. "The Science Behind Lye in Soapmaking."