How to Make Liquid Hand Soap

Learn how to make liquid soap from scratch with this simple recipe –  use this liquid soap as hand soap, body wash, pet shampoo and more!

Every year I challenge myself to make, or learn how to make, something new.  This year, one of my goals was to learn how to make liquid hand soap from scratch with potassium hydroxide (potash). 

Liquid soap is definitely one of those things that seems incredibly complicated, and some sites/tutorials really do make it that way. But this soap recipe is pretty low key and results in a beautiful soap with a combination of four different oils. 

Simple Liquid Hand Soap Recipe

• 8 oz coconut oil 
• 4 oz rice bran oil
• 4 oz olive oil
• 4 oz castor oil
• 4.63 oz potassium hydroxide (KoH) – 3% superfat
• 9.72 oz distilled water

For dilution phase:

• distilled water

Preparation:

Liquid soap uses a different kind of lye than bar soap. You’ll need to have Potassium Hydroxide for liquid soap (also known as Potash). You can source this from your local soap store or, pick up from Essential Depot on Amazon.

Using infused oil: prepare your infused oil (ie. calendula, comfrey, etc) in advance.

How to Make Liquid Hand Soap

Liquid hand soap is not difficult to make but it is time consuming. You’ll want to make it on a day that you can be home to watch the crock pot and give it your undivided attention.

Step 1: Measure lye and water

Measure out your potassium hydroxide and distilled water in two separate, heat proof containers. Wearing gloves and goggles, add the potassium hydroxide to the water slowly, stirring to dissolve well.

Step 2: Weigh your oils

Weigh out your oils and add to the slow cooker.  Turn the heat on low and add the water and lye solution to the slow cooker.  Stir the lye with the oils for 4-5 minutes until combined.

Step 3: Blend your Oils

Using your immersion blender, blend off and on until the soap reaches trace. Try to avoid running the immersion blender continually or the motor will burn out. Instead, run for 15-20 seconds, then break for 30.

At trace, the soap will be slightly foamy on top, but be starting to thicken up.

Step 4: Cook the liquid soap

Over the next 3-4 hours, cook the soap in the crock pot using low heat with the lid on. Your final cook time will vary depending on your slow cooker.

Every 20-30 minutes, remove the lid of the slow cooker and check the soap progress. Stir with a spoon or heat safe spatula. Over that few hours, the soap will turn dark, then start to gel in certain areas. I might become cloudy and separate somewhat… this is all a normal part of the process. Just use your spoon and stir everything as best as you can to get it to come back together, then continue to cook.

With the heat on low, check the mixture every 20-30 minutes for several hours. Over that time, the mixture will start to darken in color and look like a thick gel paste. My mixture cooked for just under 5 hours (but yours could be shorter or longer depending). 

When your soap turns to a thick paste that is somewhat shiny, then take out a tiny bit on a spoon and let it cool. Then mix with a bit of distilled water to dilute (it won’t completely dissolve).

Touch that diluted paste with your tongue – if it tastes like soap, then you’re done. If it zaps you.. then the mixture will has lye and needs to be cooked even further.

Step 5:  Store or dilute for soap

Now that your soap paste is done, you have a few choices. You can spoon the paste into mason jars and store in the pantry until you are ready to use it. Or.. you can dilute the entire amount and bottle it up for body wash, hand soap and even pet shampoo.

If you are diluting it, do so with distilled water. Trying to dilute with other ingredients (like milk or tea, or other liquids) will potentially complicate things especially because you will need a preservative of some type.

To determine the dilution for the soap paste, weigh the fully cooked soap paste on your scale – this batch weighed 25.5 oz. Then add 25.5 oz of distilled water to your slow cooker and stir in the soap paste. Place the lid on the slow cooker, and allow the mixture to sit overnight. Stir occasionally with a spoon or mash with a fork.

In the morning, the close should be dissolved (or close thereto)… mash any remaining paste with a fork and stir or. Or, use your immersion blender to quickly blend what’s left. If you take that route, you’ll have a creamy layer of bubbles on the top… just work with it. The bubbles will dissipate as time progresses and you stir with a spoon.

Once the soap is 100% completely dissolved, it should look like this (see above). Pour through a fine mesh strainer to catch any lumps, and store in jars.