DIY Basic 4-Oil Soap Recipe

Bottles of palm oil produced and for sale at a womens cooperative workshop near Essaouira in Morocco

Cultura RM / Philip Lee Harvey / Getty Images

If you are new to cold-process soap making—or even if you are experienced—you can't go wrong with this basic soap recipe that uses four oils. Gather the necessary equipment and ingredients, read through the recipe, review the safety cautions about working with lye and get started making soap.

Ingredients for Making Basic 4-Oil Soap

  • 6.5 ounces palm oil
  • 6.5 ounces coconut oil
  • 7.5 ounces olive oil
  • 1.3 ounces castor oil
  • 8 ounces water
  • 3.1 ounces lye
  • 1 ounce fragrance oil or essential oil blend

Equipment Needed for Soap Making

  • Kitchen scale
  • 2 heat-resistant plastic or glass pitchers
  • 1 lid for a plastic or glass pitcher
  • Rubber gloves
  • Safety goggles
  • Spoon
  • Large pot 
  • Several small glass containers 
  • Stick blender
  • Soap mold
  • Thermometer

Mixing the Lye Solution

Mixing the lye solution is the most challenging step of making cold-process soap.


Work in a well-ventilated area without any children or pets around. Lye is a dangerous chemical that can cause severe burns. Observe all cautions and safety measures when working with lye.

Everything is measured by weight when making soap, even the liquids. You'll need an accurate scale for the measurements.

  1. Put a container on the kitchen scale and zero out the weight.
  2. Put on rubber gloves and safety goggles and keep them on throughout the process. 
  3. Weigh 8 ounces of water and transfer it to a glass or plastic pitcher.
  4. Open the container of lye and gently shake the lye into an empty container on the scale until you weigh out 3.1 ounces of the chemical. 
  5. Close the lye container and put it away in a safe place.
  6. Slowly add the lye to the pitcher of water (not the water to the lye), being careful not to splash. Don't breathe in the fumes. Use a fan or open a window during the process. Do not add the water to lye.
  7. Stir the mixture gently until the lye is totally dissolved. The mixture may bubble or steam, but that is expected. Just stir until the solution is mixed completely.
  8. Immediately rinse the spoon you used to stir the solution with water.
  9. Cover the container containing the lye solution and put it in a safe place to cool. It is ready when it cools to about 100 F.

Making the Soap

Now that you've made the lye solution, you've completed the hard part of this recipe. It is time to get on with soap making. 

  1. Weigh and heat the solid oils until they are completely melted using glass containers and the kitchen scale.
  2. Put the melted oil into a large soap pot over low heat. 
  3. Weigh and add the liquid oils to the melted solid oils in the soap pot.
  4. When both the lye and the oils are at about 100 F, slowly pour the lye solution into the oils.
  5. Stir the mixture with a stick blender, alternating short blasts of the blender and stirring.
  6. Mix the soap until it reaches a light trace. "Light trace" in soap making refers to the point at which the soap is about as thick as thin cake batter and there are no streaks of oil left in the mix.
  7. Remove the mixture from the heat and add the fragrance oil. Mix it into the soap thoroughly.
  8. Pour the raw soap into the mold and let it sit for 12 to 24 hours until it cools completely and is hard enough to cut.
  9. Remove the soap from the mold and slice it into bars. Let it cure an additional two to four weeks before using the soap.