Did you know that the origins of soapmaking date back to over 4,000 years ago? Soap seems to have been invented by the Sumerians, who used it in paste form to treat skin ailments. It accompanied our ancestors in their daily lives, slowly evolving and spreading across the world until it took the form that we recognize today… We don’t know about you, but this makes us even more excited to make homemade soap and participate in its millenary history!
In this article, we’re going to learn about how to make soap with the cold process method. Cold process soapmaking allows us to retain more of the good properties of the ingredients than the hot process method, which is used industrially. The cold process method is generally used for handmade soaps.
Are you ready? Your soapmaking journey is about to begin. Thanks to this post, you’ll learn all you need to know about how to make homemade soap. What colours will you use? What scents will you choose? Don’t hesitate to share your DIY soap recipes and results in the comments!
Making homemade soap
Before you begin
Sodium hydroxide (NaOH) is indispensible in soapmaking. Commonly referred to as lye, it is a caustic product that can cause chemical burns. It’s therefore very important to wear gloves, safety glasses, and a long-sleeved shirt throughout the soapmaking process. We also recommend that you read our full article on how to use sodium hydroxide safely.
- 1 large stainless steel bowl
- 1 silicone spatula
- A few metal ramekins (for additional ingredients such as scents, colourants, exfoliants…)
- 1 large Pyrex measuring cup or HDPE pot for the sodium hydroxide solution
- 1 immersion blender
- Scales, accurate to 0.1 g and 1 g
- 1 thermometer
- A few pipettes
- Protective soapmaking gear
- Components to make a double boiler
- Soap mold(s)
- pH indicator paper (to test the soap after it has cured)
Good to know
- If you use a plastic mold, place it in the freezer for 30 minutes to 3 hours before unmolding to facilitate the process.
- In cold process soap recipes, you’ll come across a term that might be unfamiliar to you: trace. Trace refers to the point at which the oil/butter and sodium hydroxide mixture has thickened. When your soap batter has reached “trace,” the blender or a spatula leaves a trace on top of the soap batter when you gently lift it out. This tells you that it’s time to add your additives (if using) and to pour your soap batter into the mold.
Steps to follow
- Prepare and sterilize your equipment and workspace.
- Prepare the sodium hydroxide solution:
- Put on your gloves, safety glasses, and an apron. Clear your workspace, and keep children and pets at a safe distance. Make sure to prepare your solution in a well-ventilated space (under the hood of the stove, near a window, outdoors…).
- Weigh the water in a container (a Pyrex measuring cup or HDPE pot). In a second container, weigh the sodium hydroxide (lye/NaOH).
- Slowly add the sodium hydroxide to the water, taking care not to spill any. Stir until the solution is clear, then set it aside.
Caution: Do not breathe in vapours. The sodium hydroxide solution will reach a temperature of 95ºC (200ºF) and must be handled with caution.
- Weigh the butters and solid oils in a large bowl and melt in the double boiler. Once all has melted, add the liquid oils and mix well.
- Add powdered colourants and mix well.
- When the oils and sodium hydroxide have both cooled to a temperature of 37–46ºC, add the sodium hydroxide solution to the oils. The difference between the two mixtures should be no greater than 10ºC.
- Mix with an immersion blender. Stop the blender from time to time (to avoid overheating the mixture) and stir with the spatula. When stopping or starting the immersion blender, be sure that it is completely immersed in the batter to avoid splashing caustic soap on yourself or your kitchenware. If froth or foam forms on the surface of the batter, stir with the spatula until it disappears.
- (Optional) Once you’ve reached trace, add the scents and any other additives (exfoliants, dried flowers) and stir them in with a spatula.
- Pour into the mold once your additives are evenly dispersed.
- Allow the soap to harden for 24 to 48 hours (the time will vary depending on the recipe). Unmold and cut soap while wearing gloves.
- Leave soap to dry (cure) for 4 to 6 weeks. At the end of this period, your homemade soap should have a pH between 8.5 and 10. To test the pH, moisten your soap and place a pH indicator strip on it. Remove and check the colour of the paper. Refer to the box to find the corresponding pH.
Conservation and use
Made in optimal sanitary conditions, your DIY soap will keep for about 12 months.