DIY : make your own soap

Hi all! First, I’d like to thank my friend Céline, who makes her own soap and offered to show me how she does it 🙂 I couldn’t have written this article without her.

“Why make soap? Isn’t it unnecessarily complicated?” At least, that’s what I thought when Céline mentioned it for the first time.

But when I saw her at work, I understood that making soap is just like cooking, knitting, gardening… Making something with your own hands is incredibly gratifying, and absolutely essential when you spend most of the day doing intellectual work.

Making soap and other cosmetics is also a way to reduce waste. Every year, a French citizen produces in average 354 kg of household waste, and processing this waste accounts for about 3% of the country’s greenhouse gaz emissions. These are 2 good reasons to make your own cosmetics! (see Episode 3: Skin care & Beauty products)

It’s also a good idea for a present 😉

Before starting…

There a few things you should know before starting.

There are different soap making methods, we used the cold process : no heating required. Saponification is a chemical reaction between sodium hydroxyde (also known as lye or caustic soda), and oil. The reaction stops when one of the two ingredients is exhausted:

  • If it’s the oil, it’ll give you a caustic soap
  • If the sodium hydroxyde is consumed first, the soap is called a “superfatted” or “moisturizing” soap

I found most of this information on the blog Rêvons savon and Super Soap Making. Here’s a summary of the soap making process we used:

First, you need to make “lye solution” by mixing caustic soda with water, or buying ready for use lye solution. Then, weigh and mix the melted fat with the oil and let cool. When everything is at room temperature, mix the oils with the lye solution until you achieve “Trace”. Then, you can mix in all the additives, poor the soap into a mold and wait for 24 to 48 hours. Unmold the soap, cut it into individual bars and let it rest at least 1 month.

Don’t worry, everything will be explained step by step further on 🙂

Soap making safety

With a PH of 13.0, lye is highly corrosive and will cause chemical burns when it comes in contact with human skin. It causes blindness and it will cause fatal, almost irreparable injuries when ingested. In order to protect yourself you will need to:

  • Keep children and animals away
  • Wear safety glasses, long sleeves and gloves, as well as a  filter cartridge mask

Note : the filter mask is necessary only if you make your own lye solution from dry lye.

If your skin comes in contact with lye, you can apply vinegar or put the  burn under cold water for at least 10-15 minutes (I don’t know which method works best). Then, call emergency medical services, they will tell you what to do depending on the gravity of the burn.

The material

For this recipe, you will need:

  • A pot for the “bain-marie” (or double boiler)
  • A big beaker or bowl
  • At least 3 containers (jars for example)
  • A stick blender
  • A scale
  • A spoon
  • A mold that you can make form an empty juice box for example

The ingredients

Here are the ingredients you’ll need for this recipe:

The fat & oils

  • Coconut oil (250 g)
  • Powdered cocoa butter (200 g)
  • Olive oil (500 g)
  • Jojoba oil (25 g)

The additives

  • Lavandin essential oil (or another essental oil)
  • Hemp oil
  • Honey
  • Yellow coloring


Céline makes her own lye solution. She stores the dry lye in an airtight, waterproof container made for canoeing.


If you make your own lye solution, you need to precisely calculate the amount of lye you’re going to use for your recipe. You can either do it by hand, or use a lye calculator (like MMS The Sage or Mendrulandia). For this recipe, we calculated by hand as follows:

  1. Multiply the weight of each fat and oil by its saponification index: it’s the measure of how much lye is needed to transform 1 gram of oil into soap. You’ll find a table of saponification indexes here (we used the ones for caustic soda NaOH).
  2. You then need to add all the values to get the total weight of lye needed for this recipe.
  3. Calculate the superfatting in order to make a superfatted soap. Here, we used an 8% discount, which means we removed 8% of lye.
  4. Finally, you calculate the weight of demineralized water you need to react with the lye. We chose a lye concentration of 32% for this recipe, here’s the equation:

(100/32) x (final weight of lye) = total weight of lye and water

Subtract the total weight and the final weight of lye to get the final weight of water.

Now you can make your soap

1. Prepare your mold by cutting the top off an empty juice carton for example.

2. Melt the fats (coconut oil and cocoa butter) in a “bain marie” or double boiler.

3. Meanwhile, go to a well-ventilated place (under a cooker hood or outside), with the filter mask, safety glasses and gloves on. Weigh the lye using 2 glass jars. Weigh the demineralized water. Then with precaution, poor the water on the lye and not the other way around.

4. Mix gently and wait for the lye solution to become translucide.

5. Once the coconut oil and cocoa butter have melted, mix them with the olive oil (in a plastic beaker for example).


6. Poor the lye solution into the beaker and mix with a stick blender – alternating electric and manual mixing in order not to break the blender- until you achieve Trace. You can find more information on Trace here. To test for Trace, use your stick blender to drizzle a bit of the mixture on to its surface. If you see a trail of soap which takes time to dissolve back into the mixture on the surface, you’ve achieved Trace.

7. Once you’ve achieved Trace, you can mix in the additives: essential oils, coloring, honey, aloe vera gel, hemp oil… (see ingredients used for this recipe above). Mix with a spoon.

Colorants naturels et huiles essentielles

8. Mix with the stick blender again.

9. Poor the soap into your mold.

10. Do the dishes with your gloves still on.

11. Wait 24 hours, then cut the juice box and use a knife to cut the soap into individual bars (with the gloves on). Put the bars of soap into a non airtight container, such as a cardboard box for example.


Let them dry at least 1 month somewhere dark and dry like in a cupboard.

I hope you enjoyed reading this article! Please leave a comment if you did, it would make me very happy 🙂


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