How to Handle Lye Safely

Learn how to use safely use lye while making soap.

| June 2018

  • Like other household chemicals, lye can be dangerous if handled improperly, but you will rarely encounter issues if you work in a thoughtful and careful manner.
    Photo by Pixabay/heyerlein
  • “Simple & Natural Soapmaking” by Jan Berry offers everything the modern-day enthusiast needs to make incredible botanical soaps.
    Cover courtesy Page Street Publishing

Simple & Natural Soapmaking (Page Steet Publishing, 2017)by Jan Berry presents 50 easy, unique soap recipes with ingredients and scents inspired by the herb garden, veggie garden, farm, forest and more.  Beginners can join in the sudsy fun with detailed tutorials and step-by-step photographs for making traditional cold-process soap and the more modern hot-process method with a slow cooker. This section explains why lye is necessary to make soap, and how to use it safely.

A few generations ago, our great-great–grandmothers made their own lye, called potash, using wood ashes and water. They combined this highly caustic substance with fat rendered from butchered animals and boiled the mixture over an outdoor fire for many hours until a soft soap was formed. While this resulted in a truly natural soap, it was also difficult to control the quality of the final product.

These days, we have manufactured substitutes to replace that wood-ash solution. Sodium hydroxide, also called caustic soda or lye, is used to create solid bars of soap, while potassium hydroxide is used to make liquid soaps. With these standardized ingredients, the guesswork has been removed and modern soapmakers can reliably produce batch after batch of gentle, balanced soap.

Many crafty types find themselves interested in making their own soaps, but are concerned about handling lye. They often wonder if it̕s possible to make soap without it.

The short answer to this question is no. By definition, soap is what you end up with when fats and oils are combined with a highly caustic solution, no matter if it̕s our great-grandmother’s potash or our modern-day sodium hydroxide.

When lye meets oils and fats, a chemical reaction occurs that changes both substances. Once that reaction is complete, you no longer have oils or lye; you’ve created soap! If made correctly, no lye is left in the final product. It̕s all used up and transformed on a molecular level during the process of converting the oils into soap.

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