Basic Liquid Soap Recipe

  • 01 of 10

    Let's Make a Basic Liquid Soap

    Stack of soap and towels next to lotion
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    If you are comfortable with the basics of cold process soap making and looking for a new challenge, try making liquid soap. It is more complicated and takes a lot of patience. You'll likely notice a few changes in your soap making process, but if you follow the steps carefully, it is not too difficult.

    The major difference between bar soaps and liquid soaps is the alkali used to saponify the oils. All soap, whether hard or liquid, starts with a simple chemical reaction between oils and an alkali. With bar soaps, it's sodium hydroxide. With liquid soaps, it's potassium hydroxide.

    Liquid soap is a bit more complicated to make at home. For beginners, it's best to use a tried and true recipe that results in a good balance of lather and moisturizing.

    For this recipe you'll need:

    • 16.5 oz. sunflower oil
    • 7 oz. coconut oil
    • 5.5 oz. potassium hydroxide KOH
    • 16.5 oz. distilled water for the lye mixture
    • 40 oz. distilled water to dilute the soap paste
    • Either 2 oz. of boric acid or 3 oz. of borax mixed into 10 or 6 oz. of water
    • Approx. 3 oz. fragrance or essential oil, as desired
    • Soap dye or colorant, if desired

    You'll also need:

    • Basic tools for mixing the lye
    • Large crockpot
    • Thermometer, scale, measuring cups
    • Stick blender
    • Potato masher and/or flat whisk
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  • 02 of 10

    Mix the Lye-Water Solution and the Oils for the Liquid Soap

    A major difference between making liquid soap and bar soap is that that it is a "hot process" soap. Instead of relying on the heat generated by the saponification process, heat is added using a double boiler, oven, or crockpot. This recipe can be made in a double boiler or the oven, but a crock pot is preferred. It keeps everything in one pot and lets it cook evenly without having to monitor the water in a double boiler.

    Begin the Soapmaking

    Measure out your oils and put them in the crockpot on low. You want this mixture to be at about 160 degrees (give or take 10) throughout.

    While the oils are heating up, mix your lye-water, using the standard lye-making procedure. If you've never used potassium hydroxide before, don't be alarmed. It's a bit more volatile in the water than sodium hydroxide. It makes an odd boiling/groaning sound as it's dissolving. This is normal.

    When the lye-water is completely mixed and clear, slowly add it into your oils. (You don't need to wait until it is cool.) Don't turn the stick blender on just yet. Just stir the oils and lye together. Then, like in cold process soap making, start using the stick blender. At first, it will seem to want to separate. Keep blending.

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  • 03 of 10

    Bring the Soap Paste to Trace

    Depending on your mixture of oils, it will take a long time to get to trace, up to 30 minutes. "Trace" for liquid soap looks pretty much like cold process. It's kind of ​pudding-like, or a blend of pudding and applesauce, with the characteristic "traces" and/or ridges when you dribble the soap back into the pot or stir. You can't really stir it too much, so it's best to make sure you've got a good solid trace before moving to the next step.

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  • 04 of 10

    Cook the Paste for Liquid Soap

    Once the soap has reached trace, you'll need to give the soap one more good stir, shake off your stick blender, put the lid on the pot, and wait.

    Check on the soap in about 15 to 20 minutes. If there's any separation, just stir it and put the lid back on. Keep checking on the soap every 20 to 30 minutes.

    In the 3 to 4 hours it will take this soap to cook, it will transform and go through several "stages." Don't worry if you don't see one, sometimes a stage will be brief and you'll miss it. The "stages" usually are:

    1. Thick applesauce
    2. Cooked custard with small bubbles
    3. Watery mashed potatoes
    4. Solid taffy
    5. Chunky/creamy Vaseline
    6. Translucent Vaseline

    Keep stirring every 30 minutes or so through each of the stages. It will be difficult to stir through the taffy stage. Do the best you can. The potato masher will help break the taffy up. Then, just when you think it's never going to finish, it will start to get creamy and move into the Vaseline stage, getting more translucent.

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  • 05 of 10

    Test the Liquid Soap Paste for Doneness

    Once you've reached the 3 to 4-hour mark and the soap has softened and turned translucent, it's time to test it to see if it's cooked long enough. Take two ounces of boiling water and add one ounce of your soap paste. Stir the soap, breaking it up and helping it dissolve in the water. Once it's completely dissolved (several minutes) check to see how clear it is. If it's just very lightly cloudy, that's ok. The soap will "settle" after it's finished and get even clearer. If the dissolved soap mixture is milky or very cloudy, you've either not cooked it long enough or you've mismeasured something.

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  • 06 of 10

    Dilute the Liquid Soap Paste

    If the test mixture stays clear as it cools, it's good to continue. The last measure of patience is needed when diluting the paste. Take the remaining 40 oz. of distilled water and bring it to a boil. Add the water to the soap paste. Stir it in a bit with a spoon or the potato masher.

    Turn the heat off on the crockpot. Put the lid on and wait.

    After an hour or so, stir it some more. It should have softened some by now, but will likely still be very chunky and gooey. Put the lid back on and wait some more.

    You can put the lid on and leave it to sit overnight and dissolve. If you prefer a more active role, just keep waiting and stirring, waiting and stirring. The potato masher will help to break up some of the larger chunks of paste, but nothing will help more than just waiting.

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  • 07 of 10

    Neutralize the Liquid Soap

    In addition to the different alkali, and the cooking of the soap, liquid soap is different from bar soap in the way it is formulated. If you run most recipes through a lye calculator you'll see that there seems to be way too much lye! Indeed, liquid soap recipes are usually formulated with about a 10% lye excess. This is to ensure that all of the oils are saponified.

    After the soap paste has completely dissolved in the water, it's time to neutralize the soap and add your fragrance. Turn the crockpot back on and bring the mixture back up to 180 degrees or so.

    In a separate container, mix the neutralizing solution. You can make either a 20% boric acid solution or a 33% Borax (20 Mule Team) solution. For the boric acid, take 8 oz. of boiling water and add 2 oz. boric acid. For the Borax, use 3 oz. Borax in 6 oz. of boiling water. It's important to stir very well and make sure that it stays very hot. As this mixture cools, the Borax or boric acid will start to precipitate out of the mixture and it won't mix into your soap!

    Add about 3/4 oz. of neutralizer for every pound of soap paste (just the paste, not the added water.) So, for this recipe which has about 2.8 lb. of paste, add 2 oz. (2.13 rounded down to 2) of neutralizer solution. Too much neutralizer (especially the boric acid solution) can cause cloudiness, so it's best to round down and err on the conservative side.

    Slowly pour the neutralizer into the re-heated soap mixture and stir well. Add one ounce first and let it sit for a bit. Then add another half ounce. Then, if you still have no cloudiness, add the final half ounce.

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  • 08 of 10

    Add Fragrance or Color to the Liquid Soap

    After you've neutralized the soap, but while it's still hot, it's time to add your fragrance and color, if desired. A good rule of thumb is to fragrance liquid soaps at about 2 percent to 3 percent. For example with this batch, that's about 3 oz. of fragrance. Add the fragrance to the soap and stir well. Likewise, if you're adding color (remember to take the amber color of the soap base into your coloring), add it a few drops at a time, stirring well.

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  • 09 of 10

    Let the Liquid Soap Rest or "Sequester"

    Let the soap cool and pour it into large bottles or jars. Put them aside in a cool place and just let it rest. During this resting phase, the insoluble particles should settle to the bottom and any minor cloudiness caused by insoluble particles in the oils or added fragrance oils should clear up. It will need to settle for one week. When you are pouring your soap into their final bottles or tubes, be careful not to disturb the settled solids, or you'll have to let them settle out again.

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  • 10 of 10

    Enjoy Your Homemade Liquid Soap

    That's it! If you've made it this far, you've entered the world of liquid soap making. There are nearly as many recipes and variations with liquid soaps as there are with bar soaps. Different oils and slightly different techniques will all give a different final product, ranging from a light liquid hand soap to shampoo to a shower gel.