Directions
- 1Weigh out 1000 grams of avocado oil into a glass beaker on a digital kitchen scale.
- 2Add the weighed oil to your Instant Pot set on the slow cooker setting to medium.
- 3Weigh out 210 grams of potassium hydroxide into a separate glass beaker, remembering to zero out the scale with the container first.
- 4Weigh out 250 grams of distilled water into another separate glass beaker, remembering to zero out the scale with the container first.
- 5Weigh out 250 grams of vegetable glycerin into the same beaker with the distilled water, remembering to zero out the scale with the water first.
- 6Weigh out 30 grams of peppermint essential oil into a small beaker, remembering to zero out the scale with the container first.
- 7Add the essential oil to the avocado oil in the Instant Pot.
- 8In a well-ventilated area, gradually pour the potassium hydroxide into the distilled water and glycerin mixture, stirring continuously until dissolved. This is an exothermic reaction, so it will get hot.
- 9Check the temperature of the potassium hydroxide solution; it should cool down to below 175°F.
- 10Check the temperature of the oil in the Instant Pot; it should be between 160°F and 170°F.
- 11Gradually pour the potassium hydroxide solution into the oil in the Instant Pot with vigorous mixing using an immersion blender.
- 12Continue blending until the mixture reaches a thick, mashed potato-like consistency, which took 7 minutes in this video.
- 13Cover the Instant Pot and cook the soap gel, stirring about every half hour, for approximately 4 hours until it becomes translucent and gel-like.
- 14Test the readiness of the soap by adding a small amount of the soap gel to warm distilled water in a small jar and shaking it; if the solution becomes clear, it's ready.
- 15To dilute the concentrated soap gel for storage, add distilled water to the Instant Pot with the soap gel and let it dissolve on low overnight.
- 16Test the pH of the dissolved liquid soap using a pH test strip; it should be around 9.
- 17Pour the liquid castile soap into glass jugs for storage.
- 18To use as hand soap, fill a hand soap dispenser about a quarter full with the concentrated liquid castile soap.
- 19Top off the hand soap dispenser with tap water and shake to mix.
Ingredients
- 1000 grams Avocado Oil
- 210 grams Potassium Hydroxide
- 250 grams Distilled Water
- 250 grams Vegetable Glycerin
- 30 grams Peppermint Essential Oil
Equipment
Instant Potslow cookerdigital kitchen scaleglass beakerthermometerimmersion blendersilicone spatulasmall glass jarglass jugsfunnelhand soap dispenser
Tips
- For this recipe, you can use 100% pure olive oil or avocado oil as they have very similar saponification values.
- Do not forget to zero out the weight of your containers when weighing ingredients.
- The glycerin speeds up the soap-making process, so it's recommended for beginners.
- Always wear gloves and eye protection when working with potassium hydroxide, as it will burn your skin.
- When mixing water with potassium hydroxide, always add the potassium hydroxide to the water, not the other way around.
- Wait for the potassium hydroxide solution to cool down to below 175°F and the oil to be between 160°F and 170°F before mixing them.
- Use a dedicated hand mixer and spatula for soap making only, do not use them for food afterwards.
- You can test if the soap is ready by adding a small amount to warm distilled water; if the solution is clear, it's ready.
- The concentrated castile soap can be stored in glass containers in the pantry for at least a couple of years.
- When diluting the concentrated soap for hand soap, fill the container about a quarter full with soap and top it off with tap water (distilled water is no longer necessary).