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As a soapmaker, I’m annoyed I haven’t tried to figure out a liquid castile soap recipe sooner!  I use it for everything!  And by everything, I mean…. everything.  Cleaning (amazing for scrubbing bath tubs, showers, toilets, floors), shampoo, washing livestock, homemade liquid hand soap, liquid dish soap, body wash, laundry detergent… everythaaaaaang.  If you need soap for something… castile is your dude.  It’s one of those easily made natural products that will do just about anything you ask it to.

IF you’re not ready to make your own soap and would like a small business option, I will have castile soap paste AND bars of soap available in my farm store from time to time that you can purchase until you’re ready to dive into making your own.  Appreciate you!  —> shop.redfeatherfarmohio.com

Now.  This is PURE castile soap in a liquid version.  None of that added rando oils like hemp oil or palm oil or jojoba oils or castor oil like a certain company uses.  PURE, meaning made with only olive oil.  That’s what castile soap is.  Anything outside of that is wrong… but you know… if you want to do your thing… do your thing and call it what you want, I guess.  I’ll get over it.  I’m also primarily using castile soap for cleaning surfaces that aren’t my skin, so I don’t need a bunch of different oils that do it.

Making your own castile soap is rather inexpensive and is pretty easy to do.  Liquid soap is made with potassium hydroxide, unlike sodium hydroxide which is the type of lye that is used for solid bar soaps.  The process is a touch different, too, as I use hot process and cook it in my crack pot.  YEAH I SAID CRACK POT AND THAT’S HOW WE WILL CALL IT HERE AT RED FEATHER FARM.  We don’t have a crock pot.  Crackkkuhhhh pawwwtttt.  I’m rather aggressive today.  Lemme just quit with the all caps yellin’.  I’m not yelling at you… I’m just loud :D  love youuuuuuu

​My liquid castile soap paste is made with a 1% superfat and a 2.5 parts water to 1 part lye (1 part of the water/liquid portion being the glycerine).  I’m giving this information for those that may be running this through a soap calculator to double check my math and measurements, which you absolutely should be doing, or wanting to re-size the batch to be larger or smaller.  You need that information to properly re-size.  I use soap calc . net for all my recipe calculations!

​Disclaimer

This recipe is written assuming you know how to make soap, understand lye safety, and have equipment to protect yourself.  If you don’t know how to make soap, I am working on a YouTube video to get you started, but the good news is there’s sooooo many YouTube videos out there on soap safety and the likes.  But I’ll make one.  Promise.  Lye is very caustic, so understand how to use it and work with it before diving in head first.  You can burn yourself very badly, go blind, and even hurt your lungs from fumes if you’re really dumb, so just take time to learn that.  Please.  And then, you can confidently use this recipe!

Hot Process Soap

I don’t overly care for hot process soap because it gives me so much anxiety.  It’s just the process… the cooking… how the batter looks.  It’s just alll so wrong looking.  But this is from a dedicated cold process soap maker.  I’m opinionated and set in my ways if you haven’t noticed.  The beauty of hot process soap is once it is done cooking and cooled, you can use it immediately, which is what many soap makers like.  Quick turn around time.  Cold process requires time for saponification and then to cure and dry out.  While you can use it within a couple days, cold process bars would basically just melt in the bath without a 4-6 week cure time.  I’m patient though!

When making hot process soap, the easiest way to make it is using a slow cooker.  They run on sale frequently and you can pick them up at the thrift store for pretty nice deals.  You just need a dedicated slow cooker for soap (which is inconvenient to store) that is used only for soap and not to cook soup in tomorrow.

Immersion Blender

I will link my absolute beast of an immersion blender in the recipe card portion because it has withstood the test of time for me.  I not only make all of our soap, but also make it professionally and sell it.  That means I make A TON of soap every year and I have had the same stick blender since 2021.  Almost 5 years into this and it’s still going strong.  And the best part?  They’re pretty dang affordable!  

I would recommend investing in a stick blender for soap making, especially if you’re going to make castile, otherwise you’ll stir until your arm nearly falls off.  It’s possible, but a stick blender makes it that much easier, so you’ll really really be happy you got one.  Online crafting supply stores, like Brambleberry, have their own stick blenders as well that frequently go on sale, they give coupons for signing up for their email list, and such that you could grab one relatively inexpensively while you’re shopping for soapmaking ingredients and supplies.  Not affiliated, just throwing options out there.

Why You Addin’ Veggie Glycerin?!

Because I want to and you’re not my real Dad.

This isn’t a necessary ingredient, but it sure does make life easier.  Castile soap, and any soaps made with only olive oil are a booger to get to emulsify and stay that way.  Adding extra glycerin works as a solvent to help with that process so you aren’t blending and blending and blending until your immersion blender bursts into flames.  If you’re against this ingredient, by all means leave it out and the recipe measurements will remain the same.  The liquid to lye ratio would just changed to 1.5 parts liquid to 1 part lye.  

Let’s make our own liquid castile soap!

Equipment You Might Want:

• Slow Cooker
• Immersion Blender
• Digital Scale
• Lye Safe Container
• Heat Proof Spatula
• Infrared Thermometer
• pH Testing Strips
• Glass Jars with Lids

Ingredients:

• 32 ounces olive oil
• 5.96 ounces Potassium Hydroxide Lye Flakes
• 8.93 ounces distilled water
• 5.95 ounces vegetable glycerin

Step 1:  Blend

Start by weighing out olive oil and glycerin directly into the insert of your slow cooker.  Place insert into the heating element and place on low and cover with a lid.

Put on PPE and practice lye safety when handling lye!

In a lye safe container (glass, stainless steel, plastic recycle logo #5), weight out your distilled water.  In a separate lye safe container, or directly into the water if you have a steady hand, measure out the potassium hydroxide.

Stir in a well-ventilated area until the water is clear again; this takes just a couple minutes.

Remove slow cooker lid and place your stick blender into the oil, tapping to remove air bubbles.  Slowly add the lye solution down the metal part of the stick blender while pulsing the blender.

Continue blending for about 5 minutes or so.  You will see the soap go from a creamy consistency, to applesauce/gritty looking, and then back to smooth and creamy.  Once there is not gritty appearance, you can stop blending.

Step 2:  Cook

Return lid back to the slow cooker and cook for 30 minute intervals, stirring each time.  I set a timer because I’m scatterbrained.  I also check the temperature of the soap batter and make sure it stays between 170F-200F and no hotter.  I can shut the slow cooker off for about 15 minutes if it’s getting close.  Personal preference here (there will be others opinions about temperature for hot process).  The soap will thicken and take on a thick gelled and somewhat mashed potato consistency as it cooks.

After about 3 hours, you can test the pH of the soap paste or use a small spoon or whisk dipped into the paste and then put the paste into a small glass of distilled water.  If the soap paste dissolves completely clear (clarity test), it is ready and done cooking.  If it is cloudy, continue cooking another half hour and re-check.

You can also verify done-ness by testing pH as well. Liquid castille soap should fall between 8-9 pH, which on my paper tests is green. I will dip the strip straight into the soap, but I think the more proper way is to add a tablespoon of water into a cavity you make in the soap and stir it up with your finger a bit and test it that way. Whenever I’ve tested, I get the same results using either method. I’m probably a rebel pH tester now toooooooo.

Step 3:  Cool Slightly

Remove the lid from the slow cooker and pull the insert from the cooker and place onto a heat proof surface.  Allow the soap to cool a bit before placing into jars.  You can either store the paste or dilute to be ready to use.

To store the paste, spoon into clean jars or soap safe containers that aren’t deep and easy to scoop out.  I prefer to store the paste in wide mouth quart jars and add 8 ounces of paste to each jar.  Then add distilled water as I need a refill on concentrate.

​The shelf life of the undiluted paste is at least a couple years!

Ready to Use Dilution

For every 8 ounces of castile soap paste, add 24 ounces of distilled water.  This is a 1:3 soap to water ratio which I prefer.  This batch should make you about 1.5 gallons of ready to use soap.  This is what you would dilute further for things like hand soap in foaming hand soap dispensers or shampoo.  Add 15 drops of your favorite essential oils if desired!  This paste is a very strong base, so do not use it undiluted.

Notes:

You can add fragrance or essential oils if you would like at a rate of .5 ounces per lb of oils.  So for this specific batch, I would add no more than 1 ounce of essential oils, but honestly, would err on the side of smaller and do .5 ounces for the whole batch.  Add once the soap paste is cooled below the flash point of whatever essential oil you are using is.  The best way to do it in my opinion is to add essential oils when you dilute it!

If you would like to re-size this recipe to make a smaller or huge amount of soap, see above in the blog post for more information on superfat and lye water ratios.

And now you’ve made homemade liquid castile soap!  

Be sure an check out my hard bar soap recipes as well :)

​

Simple Recipe to Make Homemade Liquid Castile Soap

Print Pin Rate

Cook Time: 4 hours hours

Total Time: 4 hours hours

Servings: 3 lbs soap paste

Author: Ruby – Red Feather Farm

Equipment

• slow cooker
• immersion blender
• Digital Scale
• Lye safe container
• Heat Proof Spatula
• Infrared thermometer
• pH Testing Strips
• Glass Jars with Lids

Ingredients

• 32 ounces olive oil
• 5.96 ounces Potassium Hydroxide Lye Flakes
• 8.93 ounces distilled water
• 5.95 ounces vegetable glycerin

Cook ModePrevent your screen from going dark

Instructions

• Start by weighing out olive oil and glycerin directly into the insert of your slow cooker.  Place insert into the heating element and place on low and cover with a lid.
• Put on PPE and practice lye safety when handling lye!
• In a lye safe container (glass, stainless steel, plastic recycle logo #5), weight out your distilled water.  In a separate lye safe container, or directly into the water if you have a steady hand, measure out the potassium hydroxide.
• Stir in a well-ventilated area until the water is clear again; this takes just a couple minutes.
• Remove slow cooker lid and place your stick blender into the oil, tapping to remove air bubbles.  Slowly add the lye solution down the metal part of the stick blender while pulsing the blender.
• Continue blending for about 5 minutes or so.  You will see the soap go from a creamy consistency, to applesauce/gritty looking, and then back to smooth and creamy.  Once there is no gritty appearance, you can stop blending.
• Return lid back to the slow cooker and cook for 30 minute intervals, stirring each time.  I set a timer because I’m scatterbrained.  I also check the temperature of the soap batter and make sure it stays between 170F-200F and no hotter.  I can shut the slow cooker off for about 15 minutes if it’s getting close.  Personal preference here (there will be others opinions about temperature for hot process).  The soap will thicken and take on a thick gelled and somewhat mashed potato consistency as it cooks.
• After about 3 hours, you can test the pH of the soap paste or use a small spoon or whisk dipped into the paste and then put the paste into a small glass of distilled water.  If the soap paste dissolves completely clear (clarity test), it is ready and done cooking.  If it is cloudy, continue cooking another half hour and re-check.
• You can also verify done-ness by testing pH as well. Liquid castille soap should fall between 8-9 pH, which on my paper tests is green. I will dip the strip straight into the soap, but I think the more proper way is to add a tablespoon of water into a cavity you make in the soap and stir it up with your finger a bit and test it that way. Whenever I’ve tested, I get the same results using either method. I’m probably a rebel pH tester now toooooooo.
• Remove the lid from the slow cooker and pull the insert from the cooker and place onto a heat proof surface.  Allow the soap to cool a bit before placing into jars.  You can either store the paste or dilute to be ready to use.
• To store the paste, spoon into clean jars or soap safe containers that aren’t deep and easy to scoop out.  I prefer to store the paste in wide mouth quart jars and add 8 ounces of paste to each jar.  Then add distilled water as I need a refill on concentrate.
• ​The shelf life of the undiluted paste is at least a couple years!

Ready to Use Dilution

• For every 8 ounces of castile soap paste, add 24 ounces of distilled water.  This is a 1:3 soap to water ratio which I prefer.  This batch should make you about 1.5 gallons of ready to use soap.  This is what you would dilute further for things like hand soap in foaming hand soap dispensers or shampoo.  Add 15 drops of your favorite essential oils if desired!  This paste is a very strong base, so do not use it undiluted.

Video