How to Make Lye Soap

Soap is made by mixing lye (sodium hydroxide) and water with fats and oils. When the fats come into contact with the lye, a chemical reaction takes place which converts the fats into a new substance called soap. The process is called saponification. When mixed together and heated, the process changes the fats and the lye into a uniform solution that can then be poured into molds and left to harden. Soap cleans by acting as an agent between water and dirt. It soaks into the surface being cleaned, allowing water to wash away the dirt. Lye soap is popular for one major reason: it's simple and it works. Lye's gentleness and creaminess cannot be duplicated by any soap you find in the store. So follow these instructions and enjoy the benefits of lye soap. You will need to wear safety gear, such as goggles, gloves and a protective jacket [source: Cole Brothers].


  • 12 ounces (340 grams) lye
  • 32 ounces (907 grams) cold water
  • 16 ounces (454 grams) olive oil
  • 48 ounces (1,360 grams) lard or fat
  • 16 ounces (454 grams) coconut oil
  • Fragrance
  • Colorant

Here's what you do:

  1. Put on your safety gear.
  2. Combine the lye and the cold water, carefully, in a large bowl. Mix them slowly and thoroughly. Make sure the room you are working in is well ventilated, because the mixture becomes very hot and can emit fumes. Make sure there are no children around.
  3. Place the olive oil, coconut oil and lard in a pot and heat it over a medium to low flame. Stir continuously until the mixture reaches 130 degrees Fahrenheit (54.4 degrees Celsius). Use a food thermometer to measure the temperature.
  4. Turn the heat off and add the lye and water solution. Mix for five minutes, alternating between a wooden spoon and a spatula, until the mixture begins to harden. Make sure that nothing splashes on you.
  5. Stir in the colorant and fragrance.
  6. Pour the mixture into soap molds. Let them harden overnight [source:Mahalo].
  7. Turn the bars out of the molds and wrap them in cellophane. The soap will be creamy, oily and gentle on your skin.