While traditional castile soap only uses olive oil, you can use additional vegetable oils in place of some of the olive oil as well. For example, you can replace 16 fluid ounces (470 mL) of the olive oil with 16 ounces (450 g) of coconut oil for an extra hydrating and cleaning liquid soap. You can also replace some of the olive oil with hemp oil or jojoba oil to help fight skin inflammation and redness. Just make sure that the amount of oil used still adds up to 40 fluid ounces (1,200 mL).
Direct contact to potassium hydroxide lye flakes, and even exposure due to lack of ventilation, can burn your skin and even cause blindness if it gets in your eyes. [4] X Research source
You can buy potassium hydroxide lye flakes online and at some apothecary stores. Using distilled water is necessary because the pH and mineral content of tap water varies from one place to another. This can greatly impact the chemical reactions during the soap-making process, as well as its purity and cleaning ability. [5] X Research source If you want the castile soap to be even more moisturizing, you can add 8 ounces (230 g) of glycerin to the lye solution. [6] X Research source
After 5 minutes, the mixture will turn more opaque and begin to thicken into a pudding-like consistency.
This will ensure that the soap ingredients don’t separate as they cook in the slow cooker. As the soap cooks, it will become increasingly more translucent. If your slow cooker’s high heat setting doesn’t get very hot, you may need to cook the mixture for up to 5 hours.
If it’s still cloudy, cook the soap mixture in the slow cooker for another 30 minutes before performing the clarity test again.
Since the soap mixture and slow cooker will be hot, using hot water will keep your slow cooker pot from cracking as the result of an instant temperature change.
If you aren’t comfortable leaving your slow cooker on overnight, you can turn it off and let the soap liquefy at room temperature. If you do this, leave it for 10 to 12 hours instead of 8 hours.
To make your soap extra moisturizing, add about 25 drops of vitamin E oil to the container. You can use a funnel to help you transfer the liquid castile soap into containers without spilling. [14] X Research source
While it’s crucial that you use distilled water when making liquid castile soap from scratch, you can use regular water when making liquid soap from a bar if you want.
While you can melt bars of castile soap whole, they will melt much faster and more evenly if you grate them into small pieces. [17] X Research source Use caution when you’re using the cheese grater, as they tend to be very sharp.
Make sure that you pour the boiling water slowly and carefully so it doesn’t splash and burn your skin.
If you use an immersion blender, set it on the low or medium setting to ensure that the hot, liquefied soap doesn’t splash on your skin.
Depending on the temperature in your kitchen, it may take longer than 1 hour for the liquid to cool. If so, leave it for about 15 to 30 minutes.
Use a funnel to help you transfer the liquid castile soap into containers without spilling. [21] X Research source
