How to Make Hand Made Soap at Home – Cold Process Method

If you have been browsing through the hundreds of hand made soap recipes at the Thermal Mermaid Learning Library some of the recipes may look complicated, and it may be helpful to roll back and look at the basics of cold process soap making. This will make it easier to create your favorite recipes with those extra luxurious additives. So let’s take a look at a basic cold process recipes and look at how a combination of kitchen oils turns into a great batch of soap.

Making a bar of soap requires turning oil into soap through a process called saponification. We do this by adding a calculated amount of lye to the oil. There is a way to calculate the amount of lye you need by hand with a paper and pencil, but to keep it easy we can do all of our calculations with the Thermal Mermaid Soap Calculator.

The lye we need for bar soap is food grade sodium hydroxide (NaOH) Lucky for us we don’t need to make lye the old fashioned way. We can get lye thats already processed and purified for food grade purchase. This comes in the form of white crystals or flakes.

The recipe we will use for this basic bar will contain three oils: olive oil, coconut oil,  and lard. You can easily pick these up in your grocery store, If we run these three oils through our calculator  for a 1 lb recipe we get the following

  • 6.08 ozWater
  • 2.30 oz. Lye
  • 6.4 oz. Olive oil
  • 4.8 oz. Olive oil
  • 4.8 oz. Coconut oil

STEP ONE : First we need dissolve the lye and make a liquid solution, but doing this will create a strong chemical reaction that includes boiling water and strong fumes. Contact on skin or eyes can cause serious injury, so it’s important to take the proper safety precautions. If you would like more thorough information about lye, safety precautions, and first aid for burns, then read our article on the lye for soap making and chemical safety.

Before we make the lye water make sure you have your safety glasses, gloves, and mask. It helps to open a window. Measure out 2.3 oz. of lye and 6.08 oz. of cold distilled water. Gently pour the lye crystals into the cold water and stir. Always pour the lye into the water, never the other way around. This keeps the chemical reaction to a minimum. The reaction is instant, and you may feel the heat on your hand while you stir. It is common to see the water boil and fumes come from the surface. Stir until all the crystals are dissolved. The reaction will subside and you need to stir for about a minute. Don’t think that the water is safe to the touch just because the fumes and water has settled. This is a live chemical and is capable of burning on contact. Set this in the freezer to cool.

STEP TWO: Combine the oils into a large bowl.  Wait until the lye water has cooled to room temperature. If your water is in the freezer, this will probably take 10 minutes.

STEP THREE: Gently pour the lye water solution into the oils. Mix this with your sick blender for about a minute. It is important to emulsify the lye and oils completely. Continue to mix. At first you will notice the oils and water turn to a thin cloudy yellow liquid. The longer you mix the thicker the batter will become.


STEP FOUR: Bring the batter to trace while you continue mixing. Trace is a soaping term you will hear in nearly every cold process recipe and you will want to work with your recipe at different levels of trace depending on what it is that you want to make. For this recipe we can mix this batter until we get a thick trace.  At this stage the soap will become a thick pudding consistency. You will know when you have accomplished this when you pull your stick blender out of the batter and some of the soap is thick enough to be pulled to the surface while it follows the blender. It will lay on the surface in a soft pudding peak, and you can even 'trace' a line across the top because of the thickness.

STEP FIVE: Once your soap is mixed and has reached trace, you need to transfer it over to your mold. You can use a real soap mold, or a flat cardboard box lined in wax paper. It will take 24 hours for the batter to harden before you can remove the entire block from the mold. Then cut it into your desired pieces and set it aside. The soap will need to cure from 4 - 6 weeks before it can be used.

Finished Product


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