Liquid Castile Soap is versatile and inexpensive and can be made with just a few ingredients. To make it, you can make your own homemade solution or use a slow cooker and boiling water to melt ready-to-use solid soaps. Once you have the liquid, you can use it for cleaning, washing your hands, body and hair, doing the dishes or cleaning the shower.
Method 1 of 2: Make your own Castile soap
Step 1. Heat some olive oil
Use a measuring cup to measure out 1.25 liters of olive oil and pour it into a slow cooker. Turn on the device and set it to a high temperature to heat its contents.
- Traditional Castile soap only contains olive oil, but you can replace some of it with other vegetable oils. For example, try replacing 450 ml with 450 g of coconut oil to make the end product even more moisturizing and cleansing.
- You can also use a little hemp or jojoba oil to reduce skin inflammation and redness. Just make sure you are using 1.25L of oil in total.
Step 2. Protect yourself
Wear protective goggles and gloves and work in a well ventilated area. While waiting for the oil to heat up, put on gloves and goggles to protect your skin and eyes. Ventilate the room by turning on an extractor hood and opening one or two windows.
Direct contact with caustic potash chips or even exposure from poor ventilation can burn your skin and even make you blind if in your eyes
Step 3. Prepare caustic potash
Mix potassium hydroxide shavings and distilled water. Measure out 1 l of distilled water using a measuring glass and pour it into a large glass bowl. Then weigh 250 g of potassium hydroxide shavings (or caustic potash) and add them delicately to the water. Mix the products with a silicone spatula, stirring them slowly and carefully until the chips are completely dissolved.
- You can buy it online or in some drugstores.
- Distilled water is essential, as the pH and mineral content of tap water varies from place to place, which can have a huge impact on the chemical reactions of the manufacturing process and on the purity and the effectiveness of the soap.
- If you want the soap to be even more hydrating, you can add 225g of glycerin to the potash solution.
Step 4. Mix all the ingredients
Stir the oil in the slow cooker to make sure it is hot and well mixed (if you used several different oils). Then carefully pour the caustic potash solution into the slow cooker, adding it slowly to avoid splashing.
Step 5. Emulsify the mixture
Immerse the foot of a hand blender in the solution in the slow cooker. Turn on the unit at medium speed and blend the liquids for about 5 min moving the blender into the container to make sure all the oils and potash solution are thoroughly mixed.
After 5 min, the mixture will become more opaque and will begin to thicken until it takes on a consistency similar to that of a dessert cream
Step 6. Cook the soap
Once it thickens, set the slow cooker timer to 3 hours. Put a lid on the appliance and let its contents heat up. Stir it with a silicone spatula every 30 min.
- This will prevent the ingredients from separating when heating in the slow cooker.
- The soap will become more and more translucent as it cooks.
- If the maximum temperature of your slow cooker is not very high, you may need to heat the mixture for up to 5 a.m.
Step 7. Check the transparency
Pour some of the mixture into hot water. After about 3 hours of cooking, check if it has a translucent appearance and a gelatinous consistency. If so, take a tablespoon (15g) of it and pour it into two tablespoons (30ml) of hot water. If it melts and remains translucent, it is ready to dilute.
If it is still fairly opaque, continue cooking in the slow cooker for 30 minutes then check the transparency again
Step 8. Heat distilled water
Dose 2.5 l with a measuring glass and pour it into a saucepan. Heat it on the stove until it just starts to boil.
Since the slow cooker and its contents are hot, it is important to heat distilled water to avoid causing thermal shock that could crack the receptacle of the appliance
Step 9. Dilute the soap
Use the distilled water that you have heated. Gently add it to the contents of the slow cooker, pouring it slowly to avoid splashing it. Stir the soap and distilled water with a silicone spatula until the mixture is perfectly homogeneous.
Step 10. Let the mixture sit
Keep it warm for 8 hours. Once you have diluted the soap with the hot distilled water, turn the slow cooker to the “keep warm” function and allow the mixture to liquefy for about 8 hours or overnight.
If you're worried about leaving the slow cooker on overnight, you can turn it off and just let the soap liquefy at room temperature. In this case, let it sit for 10 to 12 hours, not 8
Step 11. Put it in containers
Use a ladle to pour the liquid Castile soap into a large glass pitcher or divide it among several small soap dispensers. You can use it as a cleaning product, as a hand soap, as a shower gel, as a shampoo, as a dishwashing liquid or as a shower detergent.
- To make it more hydrating, pour about twenty-five drops of vitamin E oil into the container.
- You can use a funnel to help pour the product into the containers without spilling any next to it.
Method 2 of 2: Melt solid Castile soaps
Step 1. Boil some water
You need 500 ml per solid bar of soap. Dose it out using a measuring cup, taking the volume needed for the number of soaps you melt. Pour it into a saucepan and heat it on the stove over high heat to bring it to a boil.
It is imperative to use distilled water to make Castile soap from the start, but when melting ready-made bars of soap, you can use tap water
Step 2. Grate the bars of soap
While waiting for the water in the pot to boil, use a cheese grater to grate solid soaps directly into a slow cooker. To do this, simply hold the grater over the receptacle of the device and slide the soaps back and forth over the blades.
- You can melt whole bars of soap, but if you grate them, they will melt much faster and more evenly.
- Be careful not to cut yourself with the rasp, as the blades are usually very sharp.
Step 3. Add the boiling water
Pour it over the grated solid soap in the slow cooker. Put a lid on the device and turn it on by setting it to a high temperature. Set its timer for 1 hour and let the mixture heat up.
Pour in the boiling water slowly and carefully to avoid splashing and burning your skin
Step 4. Stir the mixture
After heating it for 1 hour, remove the lid from the slow cooker. Stir the ingredients with a whisk or blend them with a hand blender until they are perfectly combined and the preparation is smooth.
If you are using a blender, set it to low or medium power to avoid splashing yourself with the hot liquid soap
Step 5. Let the soap cool
Let it sit at room temperature. Take the slow cooker container by the handles on the sides and remove it from the base. Place it on a trivet or on the stove off and let its contents cool for at least 1 hour.
Depending on the temperature in the room, it may take more than 1 hour for the mixture to cool completely. In this case, let it cool for about 15 to 30 minutes more
Step 6. Put it in a container
Use a ladle to take the liquid castile soap and put it in a large container for storage. If you prefer, you can divide it among several smaller containers or soap dispensers.