Recipe and instructions for how to make liquid hand soap using olive oil and coconut oil. Makes over two quarts of natural liquid soap for use in pumps and squeezy bottles
Washing our hands has never been more important, and many of us have been going through bars and bottles of soap like never before. So much so that people are running out and sometimes finding it difficult to buy. Just yesterday I went into two supermarkets trying to find liquid hand soap to no avail — it’s gone the way of hand sanitizer here, especially the good stuff. I hope you can find it a little easier in your area but if not, you can make liquid hand soap yourself.
If you’ve made bar soap before using the hot process method, then this recipe will feel familiar. If you’re mainly a cold-process soap maker, the process is entirely different. It takes prolonged heat, a different kind of lye, and a lot more time. At the end of saponification, you’ll have a soap paste that you can store for up to two years, or dilute into liquid soap on the spot. In fact, the relatively small investment in cost will make at least two quarts (two liters) of the best quality natural liquid soap you’ve ever used.
Ingredients to make liquid hand soap
This is a bastille recipe, meaning that it’s at least seventy percent olive oil. I’m using extra virgin olive oil in my batch, which is why the resulting paste and soap have a greenish tinge. If you use light-colored olive oil, then your soap will be cheaper to make and a color similar to Dr. Bronners. The other oil in the recipe is refined 76 coconut oil and it adds the lather and bubbles that olive oil soap lacks.
The other ingredients you’ll need are distilled water, Potassium hydroxide (KOH), and vegetable glycerine. Liquid hand soap has a superfat of just 3% so the glycerine helps add moisture and glide. If you’d like to scent your soap you can also add essential oils, though that’s completely optional. Those that smell nice and that have disinfectant qualities include lavandin, peppermint, and tea tree. At the end of the process, you’ll have a golden liquid soap that’s golden and translucent.
Lye: KOH vs NaOH
I’ve said it many times before, but soap making is chemistry. Soap is created through a process called saponification in which lye and oils interact in a controlled manner. In cold-process soap making, you use Sodium hydroxide (NaOH) to create hard bars of soap. In liquid soap making, you use a different type of lye called Potassium hydroxide (KOH). Also called caustic potash, it will not create solid soap and instead results in a kind of sticky vaseline-looking paste. Diluting the paste in water creates liquid soap.
Almost all KOH available to the home soap maker is only 90% pure, but you should make sure before you begin. Oftentimes, it will be on the bottle but if not, check with the retailer or look on their website for a document for the lye called an MSDS sheet. It’s a material safety data sheet and it will tell you all about what’s in it, amongst other information. If your KOH is different, make sure to rework the amount you’ll need for this recipe using the SoapCalc. It’s best to always run soap recipes through it beforehand anyway. The field it includes for KOH has a tickbox for if the potassium hydroxide is only 90% pure.
Soap making equipment
Many of the items you’ll need to make liquid hand soap are the same ones you’d use in cold-process soap making. There’s a list below that includes familiar tools such as an immersion blender and a digital scale. The one real difference is a slow-cooker/crockpot. The process needs steady, indirect, and prolonged heat for the cooking phase and slow cookers are the best tools for the job. After you’re finished making soap, the slow-cooker is perfectly fine to use to make food recipes. You don’t need to purchase one specifically for soap making.
Stovetops can have hot spots and the direct heat on a pan could be problematic. I don’t know of any soap makers that would make liquid soap using this method on a stove, but if anyone did, it would probably require cooking on a double-boiler. If you’ve made liquid soap using a stove or oven, do leave a comment and let us know about your experience.
Making Liquid Hand Soap
Making liquid hand soap has three phases: cooking the ingredients, testing for clarity and completed saponification, and liquifying the soap paste into something you’d recognize as liquid soap. Each step takes time, but especially the first and third steps. When I say time, you’d do well to set aside a weekend for this project. Some liquid soap makers have the experience of being able to make it all in an afternoon, but I don’t think that’s realistic for most. Expect that it will take longer, and take your time while making liquid hand soap and you’ll have better results.
There’s a video pin at the top of this piece that shows the various stages of this soap recipe. Have a watch to better understand the process and save it for later on Pinterest.
Most of my soap recipes are for small batches of cold-process soap. It takes about an hour or less to make them and then you forget about them for a month while they cure. Because making liquid soap takes a lot longer, this recipe is relatively larger. That way you invest the time once and have enough soap to last months, or longer.
Your final soap paste should be about 1100 g/38.8 oz/2.43 lbs, and once liquified with distilled water and glycerine, it will be at least double that. In volume measurements, that’s approximately two quarts. You could even have a lot more if you decide to add more water.
As you read below you may feel a little overwhelmed by the steps and testing. In that case, you can also make a simple kind of liquid soap by grating up a bar of soap. I go over how you make it in this piece.
Testing liquid hand soap
Liquid soap making is much more tricky than cold-process soap making because of the lye. With KOH being only 90% pure, it can cause your soap to be lye-heavy, and harsh on the skin, or overly superfatted and cloudy. You can have everything measured correctly and this can still happen because of the lye’s 10% wild card. That’s why testing your soap is so important, and unfortunately, it needs to be done for every batch of liquid soap you make.
Testing the superfat
If your liquid soap has too high of a superfat, so anything more than 3%, then it will turn your soap cloudy. It can also cause all kinds of issues once you begin adding essential oils and fragrances, and some people have reported seeing their soap separate afterward. Also, too much oil can separate anyway and float to the surface, after you dilute the soap paste in water.
After you think the soap has finished cooking, gently stir a teaspoon of soap paste into half a cup of scalding hot distilled water. Let it sit and dissolve, giving it another stir if it needs help breaking up. Let it cool completely then have a look. If there’s oil on the surface, or if the liquid is milky and opaque then you still have unsaponified oils in the paste. Continue cooking it until it’s much clearer. Just to be clear, milky means you can’t see through it at all. If your liquid is translucent then you’re good to go.
Testing for lye-heaviness
You test for excess lye by checking its pH. Dilute one part soap paste into ninety-nine parts scalding hot distilled water and cool to room temperature. Take the pH using strips (Litmus test papers) and check to see if the soap is between 9-10. Allow the paper to dry completely for the most accurate result.
Liquid soap is supposed to be alkaline, but if it’s above this amount then your soap is lye-heavy. Adjust down to the proper pH by adding diluted citric acid but don’t go below 9 or it will destabilize. Further information on testing liquid soap is over here.
Shelf-life and Preservatives
One big thing you’ll find different in my recipe compared to others is the last stage — I don’t liquefy the soap paste all at once. Whenever you add liquid water to a product, be it food, lotions, or soap, you’re creating an environment that microbes can colonize. The alkaline pH of the soap should deter most, but to be on the safe side, just wait, and liquify only the amount that you’d use in a month. Alternatively, you can liquefy it all but please add a broad-spectrum preservative to keep microbes out. There are various types to choose from, including natural preservatives.
Another thing I need to add, or rather not add. If you wanted to add things like goat milk or honey or other lovely yummy ingredients I’d encourage you to think twice. Because of the water content, your soap will already be a temptation for bacteria. Adding sugar-rich ingredients will tempt them even more! If you use them at any stage of liquid soap making, you will need a preservative to stop your soap from becoming a microbe breeding ground.
Natural Liquid Hand Soap Recipe
- Various kitchen bowls
- 181 g Potassium hydroxide (90% pure) 6.39 oz
- 550 g Distilled water 19.4 oz
Make the Soap Paste
- Prepare your workstation with your tools and equipment. Put on rubber gloves, eye protection, and an apron. Carefully pre-measure the ingredients. The oils in the slow cooker, the water in a heat-proof jug, and the lye (KOH) in another container.
- Turn the slow cooker on to high heat and melt the coconut oil. When it's liquid, continue to the next step but keep the heat on.
- Dissolve the lye crystals in water. In an airy place, outdoors is best, pour the lye crystals into the water (not the other way around) and stir well. Don't be alarmed if it fizzes and crackles as this is normal for KOH. If you've made soap using sodium hydroxide, please note that the reaction between KOH is a little more active. Stir until the lye is completely dissolved.
- Pour the lye solution into the melted oils. Now it's time to blend. Put the immersion blender in the slow cooker and, turned off, use it as a spoon to gently stir the ingredients together. Bring it to the middle of the slow cooker next, press it right against the bottom and turn it on for a few seconds. Don't move it around while it's on. Now turn it off and use it to stir again. Repeat this until you see the batter thicken slightly. Put the lid on the slow cooker and allow it to sit for five minutes before coming back. The soap batter may look a little separated or chunky and different from other types of soap you've made before. Don't be too concerned.
- Repeat this process of stirring and blending and allowing to sit for a few minutes. After fifteen to thirty minutes it will thicken up to very thick 'Trace'. Keep stick blending until the soap becomes thick like really dry mashed potatoes and it becomes difficult to stick blend any longer.
- Time to cook. All this time the slow cooker has been on high heat and that's where you're going to leave it for at least the next three to six hours. Put the lid on, and let it cook for that time, stirring every thirty minutes. You can set a timer if that helps. During that time, the texture of the soap will change dramatically -- from the runny custard to mashed potatoes, to puffy taffy, to glue, to something that looks like a puffy mess with chunks of greenish or golden amber.
- Finally, after hours of cooking and stirring, the soap will all look amber paste. Some soap makers describe it as looking like vaseline. Once your soap looks like that, it's probably fully cooked. This soap paste is the first major step in creating your liquid hand soap.Note: if you cook and cook and don't seem to get anywhere. Unplug the slow cooker, cover it with a towel and let it sit overnight. Have a look the next morning and see what it looks like. Sometimes just letting it sit in residual heat overnight does the trick. If this doesn't work, keep heating it the next morning.
Testing the soap
- You now need to know if the soap is actually complete and if it's lye-heavy or not. Let's begin by seeing if there's unsaponified oil in the soap.Gently stir a teaspoon of soap paste into half a cup of scalding hot distilled water. Let it sit and dissolve, giving it another stir if it needs help breaking up. Let it cool completely then have a look. If there's oil on the surface, or if the liquid is milky and opaque then you still have unsaponified oils in the paste. Continue cooking it until it's much clearer. Just to be clear, milky means you can't see through it at all. If your liquid is translucent then you're good to go.
- Test the soap for excess lye by checking its pH. Dilute one part soap paste into ninety-nine parts scalding hot distilled water and cool to room temperature. Take the pH using strips (Litmus test papers) and check to see if the soap is between 9-10. Allow the paper to dry completely for the most accurate result.Liquid soap is supposed to be alkaline, but if it's above this amount then your soap is lye-heavy. Adjust down to the proper pH by adding diluted citric acid but don't go below 9 or it will destabilize.
Diluting the soap paste
- Once you've tested the paste, you can now dilute part or all of it. If you dilute the full amount, then you'll have more soap than you'll probably be able to use in a month. In that case, you will need to add a suitable broad-spectrum preservative. Alternatively, keep the soap paste stored in a jar and dilute part of it at a time. The soap paste does not need a preservative and has a shelf-life of up to two years. The shelf-life will be the closest best-by date of the ingredients you use (check your bottles). You can also use the soap paste on its own without diluting it.
- 100g of soap paste will give you approximately 200ml of liquid soap. Use more or less depending on how much soap you need. Measure the amount back into the slow cooker.
- Add the distilled water and glycerine to dilute the soap paste.Multiply the weight of the soap paste you're using by 0.8 -- this is how much distilled water you add to the slow cooker.Multiply the weight of the soap paste you're using by 0.2 -- this is how much vegetable glycerine you add to the slow cooker.
- Turn the slow cooker on to high and warm the contents through. Gently stir, turn the heat to keep warm, and leave for an hour. Come back after that time, stir again, squish any blobs gently, and turn the heat off. Cover the slow cooker with a towel and leave it to sit for several hours, if not overnight. The soap paste will go soft and mushy in the same way that a bar of soap will do if you leave it sitting in water. If you come back and it's not fully soft, you can add a little more heat and more gentle stirring. It's not an exact science, this part, and patience is essential.
- When it looks fairly liquid, cool it completely, and strain the soap through a sieve into another bowl. This will catch any chunks of soap paste. Add 10-20 drops of essential oil (per 200ml) if you wish, the preservative if you're using one, and bottle it up in squeezy bottles or pump bottles. It's ready to use immediately.
Further resources for making liquid soap
If you’re interested in learning more about the art of making liquid soap, shampoo, and other liquid cleansers, check out these books
- Liquid Soapmaking: Tips, Techniques and Recipes for Creating All Manner of Liquid and Soft Soap Naturally, by Jackie Thompson
- Making Natural Liquid Soaps: Herbal Shower Gels, Conditioning Shampoos, Moisturizing Hand Soaps, Luxurious Bubble Baths, and more, by Catherine Failor