Making liquid soap into bar soap is a bit of a challenge compared to the reverse process because it involves removing moisture from the liquid soap and transforming its composition into a solid form. Below, I will provide you with a step-by-step guide to attempting this transformation. Keep in mind that commercial liquid soaps may contain additional ingredients that could affect the solidifying process.
Understanding the Process
Liquid soap is typically made with potassium hydroxide as the saponifying agent, while bar soap is often made with sodium hydroxide. Simply removing water from liquid soap will not result in the same composition as bar soap. However, you can attempt to create a soap-like solid by evaporating the water and adding a gelling agent or thickener.
Gather Materials
To start, you’ll need the following materials:
- Liquid soap (preferably unscented and uncolored)
- A heat source like a stove or crockpot
- A cooking pot or crockpot
- Spatula or wooden spoon
- Gelling agents or thickeners (e.g., gelatin, agar-agar)
- Molds for shaping the bars
- Parchment paper
Step 1: Evaporate the Water
Carefully pour the liquid soap into the cooking pot and set it on your stove at the lowest heat. Your goal is to slowly evaporate the water without burning the soap. Stir continuously to prevent the soap from sticking to the bottom of the pot. This process may take several hours depending on the amount of liquid soap you’re trying to solidify.
Step 2: Add a Gelling Agent or Thickener
Once the liquid soap has significantly reduced in volume and has started to thicken, it’s time to add a gelling agent. Gelatin or agar-agar can be used for this purpose. Follow the instructions on the packaging of the gelling agent to determine the correct amount to add to the mixture. Dissolve the thickener in a small amount of water and then add it to the thickened soap, stirring constantly until well mixed.
Step 3: Mold the Mixture
Once the mixture has reached a gel-like consistency, remove it from the heat. Immediately pour or spoon the mixture into molds. You can use silicone baking molds, plastic containers, or any other mold shape you desire. Lightly grease the molds with a little oil to make the soap bars easier to remove later.
Step 4: Set and Cure
Allow the soap to cool and set in the molds at room temperature. You can also place them in the refrigerator to speed up the setting process. However, be aware that this may result in a less smooth surface for your soap bars. Once the soap is firm, carefully remove it from the molds and wrap it in parchment paper. Allow the soap to cure for a few days to ensure that it’s completely set and to allow any residual moisture to evaporate.
Final Considerations
Creating bar soap from liquid soap is not a typical soap-making process and may not produce results similar to commercially manufactured bar soaps. The end product may have a different texture, lathering properties, and stability compared to conventional bar soaps. Also, consider that some additives in commercial liquid soaps, such as preservatives and fragrances, might not react well to this process.
Experiment with small batches to perfect your technique and adjust your recipe as needed. If you are looking to create soap from scratch, learning traditional cold process soap-making with sodium hydroxide might provide more reliable results for bar soap.