An introduction to seven creative ways how to make soap at home including cold process, hot process, liquid soapmaking, melt-and-pour, and rebatching. Use one or all of these methods to make homemade soap from the comfort of your own kitchen.
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Before I made my first batch of homemade soap I studied different methods to see which would be best for me. What I found is that there are two main ways to make soap but quite a few other methods too! I eventually settled on the cold process as my favorite, but I use the others when I need them. It’s important to understand that there are a number of soapmaking methods and you can choose whichever suits you.
Your choices could be based on your budget, ethos, interest, accessibility, and/or time. You could start from scratch, and choose every single ingredient down to the scents, colors, and design. You could also make homemade soap using a premade base that you melt in the microwave. Each soapmaking method has its pros and cons and I go through each below. Which type(s) you use are personal preference but some are easier than others.
As you read through the methods, check out other resources such as the Lovely Greens Guide to Natural Soapmaking, and don’t feel that you have to choose just one method. You can experiment with several or all of them if you wish. Each way is like a tool in your soapmaking toolbox and will help you to never rely on store-bought soaps again.
An Introduction to Soapmaking Methods
I mainly share cold-process soap recipes here on Lovely Greens, and we’ll get to that further below. The other ways to make soap can be much different. However, all will result in bars or liquid that you can use to clean your skin, dishes, or home. One method isn’t better than the others though you will of course end up with a favorite! We all do.
It’s also important to know that some methods of making soap are better for certain purposes than others. That means that you could use a number of them in your hobby or business. So even if you’ve been making soap for years, you may want to try another method and see what you think. You could even creatively combine one or two of them together!
Before we continue on the methods, there’s one thing that I need to emphasize. ALL real soap, at some stage, has been made with lye. It’s just what soap is! In another article, I explain what is soap if you want to learn more. There are ways how to make soap without handling lye if you’d like to avoid fumes and safety concerns. However, making soap from scratch is like magic and I don’t want you to miss out on it from a fear of lye. Lye can transform with fats into the most natural and gentle cleanser on the planet.
1. Melt and Pour Soap
- Pros: no handling of lye required, easy and quick, can be made with kids, can be used right away, reliable, no curing time, no safety gear necessary, can be made in minutes
- Cons: less control over the ingredients, not 100% handmade, can sweat or burn
The absolute easiest way to make soap is by using a pre-made soap base. Melt-and-pour soap comes in either cubes or blocks and you can choose from clear (glycerin), goat milk, and standard bases. All of the chemistry is finished for you before you even open the package which means less to be wary of. Also, more to have fun with!
To use it, all you do is cut it into small pieces and melt it either in the microwave or over low heat. When it’s melted you can add scents, flowers, and exfoliants (like pumice, oatmeal, or ground coffee). You can also add very small amounts of extra oil, like melted shea butter or sweet almond oil to melt-and-pour soap bases for added conditioning. Color can also be added to melt and pour soap at this point before you pour the batter into molds. Spray the tops with alcohol to reduce air bubbles and create a smooth finish. As soon as it’s hard, pop the bars out of the molds and use them immediately.
Pros of M&P Soap
Melt-and-pour soap has a lot going for it. It’s GREAT for beginner soap makers or if you’d like to make soap with kids. That’s because there’s no lye handling step to be cautious of and you can use the bars right away. You don’t need to wear safety gear when you make it and you don’t need extra equipment like an immersion blender. I also have a melt-and-pour soap recipe that you might want to try.
Cons of M&P Soap
One of the downsides to m&p is that you can’t use fresh ingredients with it, like milk and purees. Raw ingredients don’t preserve well in m&p soap and will eventually begin to rot. You also cannot choose the oils that go into m&p bases. The ingredients used are a mix of natural and synthetic materials and palm oil is usually present in some amount. Though you can add very small amounts of extra oil to m&p, it can cause the bars to sweat. Melt-and-pour soap can also be overcooked and burned and once it begins to cool it hardens quickly.
2. Cold Process Soapmaking
- Pros: Full control over ingredients, creates smooth bars, can do intricate patterns and swirls, can use fresh plant-based ingredients
- Cons: requires lye and the bars need 4-6 weeks to cure before it can be used
My favorite way of making soap is by using the cold-process method. You begin with soap recipes made up of whole ingredients including oils, essential oils, lye, and water and through the wizardry of creative chemistry, they’re transformed into handmade soap. It involves a series of steps but the main one is stirring liquid oils together with the lye solution. Some people are hesitant about using lye, also called sodium hydroxide, which is one of the drawbacks. However, what I love about cold process soapmaking is the aspect of making soap from scratch and that there are so many ways to naturally color, naturally decorate, and scent your bars.
How Cold Process Soap Making Works
In cold process soapmaking, you combine oils and butters, such as coconut oil, olive oil, tallow, lard, and shea butter, with a lye solution in a stainless steel pan and bring it to trace. Usually with an immersion blender, but some recipes only take mixing with a spoon or whisk.
Trace is the stage where the ingredients begin to saponify, a chemical reaction that results from combining fat and lye. The soap mixture is still semi-liquid at this point and you can scent, color, swirl, and create intricate designs in it. You pour the soap batter into a mold either before or after you color it then allow it to harden. The result is a bar soap that you can use to clean your skin and sometimes even your hair. It will need four to six weeks of curing before you can use it though.
Cold-process soapmaking is my hands-down favorite way to make soap since you have complete control over ingredients and soap additives. You can also use fresh plant material such as pumpkin puree to naturally color soap. Also, while adding liquid milk to m&p and rebatched soap is not feasible, you can add it to cold-process soap. Dairy milk, such as goat milk, gives soap bars luxurious creaminess. Heck, you could even add coconut milk, honey, or calendula flower petals to your cold process recipe if you’d like. For a full walk-through on this soapmaking method check out this free soapmaking series.
3. Hot Process Soap
- Pros: Full control over ingredients, saponification process complete in the pot, superfat controlled
- Cons: requires lye, takes longer to make than cold-process, and bars might also be rustic in appearance
What I like about hot-process and cold-process soapmaking is that you can use nearly the same recipe for both. The main difference in the recipes is that you use more water in hot process than in cold. That’s because water evaporates from hot process soap while you’re making it. You need extra water to keep the soap batter fluid.
Unlike cold process, hot process is cooked, typically in a crockpot, after you bring it to trace. This extra cook time completes the saponification process by the end of the cook. With cold process, it usually takes 48 hours for the majority of the lye and fats to saponify. When the cooking phase of hot process soap is finished, you can add extra ingredients and then pour the soap batter into molds. After it hardens you cure it just like cold process.
Pros of Hot Process
Two major bonuses with hot process soap are that you can 100% control the superfatting oil and, if you’re working with a good recipe, there is zero lye left in the soap after you spoon/pour it from the pot. In cold process, saponification takes a couple of days and during that time the lye reacts with whatever oils it wishes to. In the end, the extra oil left in the soap is a combination of all the oils used. Not so with hot process. In hot process, you can add the superfat oil after the cook, and all of that oil will stay in the final bars as the superfat.
Though many sources say that you don’t need to cure hot-process, you should really allow it to cure for the same amount of time as cold process (4-6 weeks). It’s because the water in hot process soap needs quite a bit of time to evaporate out and also the crystalline structure needs that much time to fully develop. Though technically usable the day after making it (in that you won’t get a chemical burn), hot process soap has better lather and is more gentle if given the full time to cure. Here’s a hot process soap recipe to try.
Cons of Hot Process
In hot process, you need to work with lye just as in cold process. Another potential downside is that the look of the bars is generally rustic and textured — if you want truly smooth bars, stick with cold-process or melt-and-pour. There is a soapmaking technique called fluid hot process soap that soap makers use to create colored and patterned soap. It’s not comparable to cold process in my opinion with the results of fluid HP being comparable to a design made with crayons compared to one made with markers (cold process).
4. Rebatched Soap
- Pros: no lye required, recycles scraps, can help salvage batches that have gone wrong
- Cons: the shreds of soap are often visible
If you have soap scraps or a box of ‘ugly soap’ you can salvage it by transforming it into a new batch. It could be bars that have lost their scent, scraps of bars you’ve made or purchased, or batches that went wrong in some way but are still safe. Using previously made cold process or hot process soap to make new bars is called rebatching. With this method, it’s important to not use soap that has Dreaded Orange Spot (DOS) and/or that has gone rancid as this method will not save them.
How to Rebatch Soap
There are two main ways to rebatch soap — a full rebatch or a partial rebatch. In a full rebatch, you grate the soap bars up then melt it gently with a little distilled water in a slow cooker. When the soap batter is liquid enough, you add any extra fragrance or color that you’d like then pop it into a mold (I recommend a loaf silicone mold) and let it harden. After that, you cut it into bars, cure it, and use it as you would any other bar of soap. I share the entire process in my recipe for rebatched parsley soap.
If you rebatch bars that have already been fully cured once, you can technically use the new ones right away. The water content of rebatched soap means that it can disintegrate a lot quicker though so it’s best to cure it.
When rebatching soap you can only add ingredients that are shelf-safe. That means you cannot add milk, juice, fresh plant material, or anything else that would rot or go off if left in an open container. You can use hydrosols, essential oils, clays, dried flower petals, and dried herbs.
5. Partially Rebatched Soap
- Pros: recycles scraps, can help salvage soap batches that have gone wrong, texture more even than rebatched soap
- Cons: requires lye, the texture might be a little rustic in appearance
In a full rebatch, all of the soap is made from previous soap batches. You can also do a partial rebatch where only some of the soap is old, and the rest is fresh new ingredients. When you partially rebatch soap, the finished bars can be much more homogenous than in a full rebatch.
In this method, you measure out the ingredients needed for a new recipe of cold process soap. You will also need finely chopped or grated old soap in a quantity that is no more than forty percent by weight of the base oils used in the new recipe. For example, if you’re going to make a partial rebatch with this 1-lb (454 g) honey soap recipe, then the amount of grated soap you’d use would be no more than 6.4 oz (181 g).
Recycling Old Soap into New
Making partially rebatched soap is exactly the same as making cold process with one difference. You blend the soap pieces into the liquid oils before you add the lye solution. You need to spend several minutes doing this since the more liquified the pieces become, the smoother your bars will be. Use an immersion blender but do let it rest every now and again since you don’t want it to burn out. After you introduce the lye solution and stick blend, pour the traced soap into molds and then cut and cure as if it were all new cold process soap.
6. Liquid Soapmaking
- Pros: Can be more convenient, liquid soap paste stores well
- Cons: More complicated and time-consuming than other soapmaking methods
True liquid soapmaking uses a crockpot/slow cooker just like hot process but the process and ingredients are a little different. The most obvious differences are the type of lye that’s used and that the end product is a paste-like soap. It’s neither a solid bar nor liquid at that stage so it can be a little confusing.
First off let’s chat about the different types of lye. In cold and hot process soapmaking you use sodium hydroxide (NaOH) but in liquid soap making, you use potassium hydroxide (KOH). Both are caustic substances that make soap but different types of soap.
In the case of KOH, it creates a paste after the cook that you can store in a jar until needed. KOH is also less pure than NaOH so you have to add 10% extra into the recipe. It’s an awkward one! Also, for liquid soap to be clear you have to work with a low superfat of about three percent. Any more than that and the liquid soap will turn cloudy.
Two Ways to Make Liquid Soap
To make fully liquid soap you dilute the paste in warm water, and sometimes other liquids such as glycerin, and put it into a dispenser. I have a recipe for how to make liquid hand soap if you’d like to see how to make it from start to finish.
There’s also a hack for how to make liquid soap that begins with a bar of solid soap. It’s really easy but the soap isn’t as good as recipes made from scratch. In the hack method, you grate a bar of pre-made cold or hot process soap and heat it in distilled water. It eventually disintegrates into an opaque soapy liquid that you can use in dispensers.
7. Make Plant-Based Saponin Soap
- Pros: No working with lye necessary, almost entirely plant-based
- Cons: Only a mild watery cleanser, does not store for more than a few days
There’s another way to make a natural cleanser but not through the saponification process. It’s not true soap, which is why I’ve saved this last method for last. Wild and even partially domesticated plants around the world contain soapy compounds called saponins. Also called triterpene glycosides, they can produce foamy bubbles and mild cleansing properties for textiles, surfaces, and skin.
You usually extract the soapy qualities from the plant material in bowls of warm water and then use that liquid to clean surfaces, textiles, skin, and hair. Soapwort is the most well-known of the soap plants. If you’re interested in it, I include a recipe for soapwort cleanser in my book, A Woman’s Garden. Other soap plants include English ivy, horse chestnuts, clematis, and wild native plants around the world. Learn more about saponin-rich soap plants.
Learn More About How to Make Soap
These seven ways to make soap are simply an introduction. You can learn a lot more about them though, especially cold-process soapmaking, here on Lovely Greens. I believe that beginner soap makers need to focus on technique rather than formulation so have loads of easy soap recipes to get you started. Using a lye calculator and understanding fatty acid profiles can be daunting and the recipes make that part easier.
If you are a beginner, I do encourage you to read through this series to better understand the cold process method. It’s the best way to make soap in my opinion! However, just as in hot process soapmaking, it’s best to understand the caution around handling and using lye. The second part of the series, equipment, and safety, covers more on that but if you wear long sleeves, rubber gloves, and safety goggles you will be geared up and safe. If you’d like to have a guide that you can print out, get a copy of the Lovely Greens Guide to Natural Soapmaking.