How to Make Liquid Castile Soap: Uses and List of Ingredients.

How to Make Liquid Castile Soap:  Castile soap is an amazingly versatile vegetable-based soap that’s made free of animal fats and synthetic ingredients. This natural, nontoxic, biodegradable soap is available in bar or liquid form. … It gets its name from the Castile region of Spain. These days, the soap is also made with coconut, castor, or hemp oils.

Like any true soap, liquid castile soap is made through the chemical reaction of fats and a very strong alkali called lye. This reaction is called saponification; when it’s complete the fat and lye are totally transformed into a new thing we call soap.

To make liquid castile soap, you can mix and cook your own soap solution at home. Here is the steps and materials you need to get started.

Ingredients for making Castile Soap
  • Large slow cooker (6 quarts or larger)
  • Immersion blender
  • Measuring cups
  • Silicone spatula
  • Glass mixing bowl
  • Potassium hydroxide lye flakes
  • Distilled water
  • Olive oil
  • Optional additional oils (olive oil, coconut oil, hemp oil, jojoba oil, vitamin E oil)
  • Glass container(s)
Quick steps you need to take note in making Castile Soap
  • Add the olive oil and coconut oil to a large, (6 quart minimum) crock pot. Turn the crock-pot on high.
  • While the oils are warming, put on your safety gloves and goggles, and carefully measure the potassium hydroxide lye into a stainless steel or pyrex bowl.
  • Measure the water into a medium stainless bowl or pyrex pitcher. Set the container with the water into your sink, then very carefully tip the lye flakes into the water. Stir to dissolve.
  • When the oils in the crockpot are warm, carefully tip the lye solution into the oils. Leave the crockpot on high.
  • Use an immersion blender to blend the oils and lye solution together. Immediately after adding the lye solution to the oils, blend for about 5 minutes, until the mixture looks uniformly opaque and begins to slightly thicken. For the next 30 minutes, come back and blend the soap paste about every 5 minutes. The mixture will get thicker and thicker, progressing through an icing texture to something like Elmer’s glue.
How to Make Liquid Castile Soap At Home

1.  Put 40 fluid (1,200 mL) of olive oil to your slow cooker on high heat. First, use a measuring cup to measure out and pour 40 fluid ounces (1,200 mL) of olive oil into your slow cooker. Then, turn the slow cooker on high to heat the oil.

  • 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).

2.  Wear your safety gloves and stay in a ventilated space. While the oil is heating up, put on safety gloves and goggles to protect your skin and eyes.  Then, ventilate your space by turning on the vent hood and opening 1 or 2 windows.

  • 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.

3.  Add the potassium hydroxide lye flakes with distilled water. Use a measuring cup to pour 32 fluid ounces (950 mL) of distilled water into a large glass mixing bowl. Then, measure out 9 ounces (260 g) of potassium hydroxide lye flakes and add them carefully to the distilled water. Use a silicone spatula to mix the lye solution, stirring slowly and carefully until the flakes are completely dissolved.

  • 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. If you want the castile soap to be even more moisturizing, you can add 8 ounces (230 g) of glycerin to the lye solution.

4.  Stir the oil and add the lye solution into the slow cooker. First, use your spatula to stir the oil that’s been heating up in the slow cooker to make sure it’s warm and mixed, if you used more than 1 type of oil. Then, carefully pour the lye solution into the slow cooker, adding it slowly so the solution doesn’t splash.

5.  To blend the oil and lye together, Use immersion blender. Place the end of your immersion blender into the slow cooker. Then, turn it on the medium setting and blend the liquids for about 5 minutes, moving the blender around in the slow cooker to make sure all the oils and lye solution are mixed.

  • After 5 minutes, the mixture will turn more opaque and begin to thicken into a pudding-like consistency.

6.  Allow the soap to cook for 3 hours, Make sure you cover it and  stir every 30 minutes. Once the soap mixture thickens, set the timer on your slow cooker for 3 hours. Cover the slow cooker with the lid, returning to stir the mixture every 30 minutes with a silicone spatula.

  • 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.

7.  Put 12  (14 g) of the soap mixture to hot water to test the clarity. After about 3 hours, check to see if the soap looks translucent with a gel-like consistency. If it does, use a measuring spoon to transfer 12 ounce (14 g) of the soap mixture into 1 fluid ounce (30 mL) of hot water. If the soap melts and remains translucent, it’s ready to be diluted.

  • If it’s still cloudy, cook the soap mixture in the slow cooker for another 30 minutes before performing the clarity test again.

8.  Heat 10 cups (2,400 mL) of distilled water on the stove. Use a measuring cup to measure out and add 10 cups (2,400 mL) of distilled water to a pot. Then, heat the water on the stove until it just starts to boil.

  • 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.

9.  Dilute the soap mixture with the 10 cups (2,400 mL) of hot distilled water. Carefully add the hot distilled water into the slow cooker, pouring slowly so it doesn’t splash on your skin. Then, use a silicone spatula to stir the soap and distilled water until combined.

10.  Leave the slow cooker covered on the warm setting for 8 hours. Once the soap mixture is diluted with hot distilled water, set your slow cooker on the “keep warm” setting. Leave the soap to liquefy for about 8 hours or overnight.

  • 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.

11.  Transfer the liquid castile soap into a container(s) to store it. Use a ladle to transfer the liquid castile soap in a large glass jug, or separate it into several smaller soap dispensers.[21] You can then use your liquid castile soap as a cleaning solution, hand wash, body wash, shampoo, dish soap, or shower scrub.

  • 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


Uses of Castile Soap

It can be used for so many things including: shampoo, body wash, hand soap, countertop cleaner, dish soap…and much more. I use Castile soap as dishwashing soap, laundry detergent, hand soap, countertop spray, and soft scrub on a daily basis, but the uses are endless. Here are some of the regular uses.

1. Natural Body Wash

Castile soap on its own makes a great body wash, but adding a bit of moisturizing honey and some skin-nourishing oils can take it to the next level! Get the recipe for my natural 4-ingredient castile soap body wash at the link below.

2.  Fruit & Veggie Wash

Use castile soap to make a cleansing solution for washing fresh produce. Fill your sink or a large bowl with water, then add 1/4 teaspoon of castile soap. Dunk your produce into the water and swish it around to knock any dirt or debris loose. Then rinse your produce under clean, cool water and it’ll be ready to eat!

3.   Foaming Hand Wash

Use castile soap to make a great foaming hand soap at home! Just stir together castile soap, a bit of coconut oil, and some germ-fighting essential oils, and pour it into a foaming soap bottle.

4.  Hand-Washing Dishes

Fill your sink with 10 parts warm water and 1 part castile soap. Use the wash solution to wash and rinse your dishes as usua

5.  Window Cleaner

If your windows need a lot of help in the cleaning department, use castile soap to help power through the grime. Add 1 tablespoon of soap to 1 quart of water, then pour the mixture into a spray bottle. Spray it liberally onto your windows, then use a sponge or scrubber to power through the grime and then rinse.

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