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Making Cold Process or Hot Process Soap

Updated on March 24, 2011

Soap is the result of a chemical reaction between caustic sodas and fats or oils. In fact soap was originally discovered because of mixing ashes, which naturally contained lye (sodium hydroxide), and oils. They then used these for cleaning and bathing. Later processes removed the lye from the ashes using lye water methods. While making soap in your kitchen is a lot easier then it was days gone by, it is still based on the basic principle of mixing lye and oils or fats. It is also very rewarding. You can create beautiful soaps as well as creating soaps that are wonderful and can help with certain skin problems, that can make fantastic gifts, and that you can even sell.

Soap Making Processes

There are three basic soap making processes (though only two of them are "from skratch").

Melt and Pour-The easiest soap making processes is melt and pour (or milled soap if you wish). This is the process of taking a soap base (that is already made) and melting it. You then add extra skin benefiting oils, herbs, fragrances, and colorants to achieve a beautiful soap. This can be a lot of fun, easy, and is easy enough for older children to do without worrying about lots of dangers.

Cold Processes Soap Making-For those who desire to make soap from scratch, cold processes is the most popular form. It is fairly quick and easy.

Hot Processes Soap Making-Hot processes soap is very similar to cold process except that the soap is cooked and finishes forming the same day. Otherwise soap has to cure for four weeks before being used.

The Actual Processes

You will need: You will need lye, water, oils or fats, and any additives, fragrances, or colorants you wish to add. This will let you make soap that meets your needs. For example each oil has an advantage and can change how quickly the soap lathers and even the size of the bubbles that lather, but they can also add good things to your skin. Choosing your products may take a little research.

Getting Started: You will want to melt and warm all of your oils and fats together. This should be done in a good sized pan on your stove. You will want to carefully measure out your ingredients according to your recipe so that there is enough oil/fat to completely turn all of the lye into soap.

Dealing with lye: In a good sized glass pyrex measuring cup you will want to measure out your liquid (usually water) and add the lye slowly to the water. It is a good idea to wear gloves, safety goggles, and a rubber apron to protect yourself from splattering lye. The lye water will get very hot very quickly. You will then need to cool the lye water to about 110 degrees and your oils down to about 110 degrees.

Hot process: If you are doing hot process soaps you will then want to pour the lye water slowly into the soap. You will then slowly cook the soap for four to six hours as you stir it every now and again. Toward the end you will want to add extra oils (if you wish), fragrance (if you wish), and or colorants (if you wish). You can also add great things like sugars, honey, and herbs. You will want to thoroughly stir these items in. Then press your soap into molds or roll them into soap balls. Let them sit for about 24 hours and remove them from the molds or cut them into bars or chunks. These soaps should harden at least three days, but then can be used.

Cold Process: Cold processes soap is used more often because it is easier to get a smoother soap and better looking soap with your colorants and additives. However, it has to cure for four weeks before being used. The process starts out the same. You will want your oils and your lye to be about 110 degrees. Then slowly add your lye to your oils by dribbling it in and stirring slowly. You will then want to stir your soap as you mix in your lye. This could take some time and you can use an electric mixer on low (as long as you aren't planning on eating with it) to mix for you. You are looking for "trace" which can be identified by lifting some soap out of the pan and dribbling it on the surface. If your soap has traced you will get a pile on the surface that will last for some time before joining the rest of the pan. At this point you can pour your soap into the molds after adding any extra additives such as herbs, colorants, or fragrances. Leave them there 24-48 hours and then remove from the molds and cut if needed. You don't want to touch it bare handed yet. You will need to cure it for four weeks first. Then you can use the soap.

Cautions: Working with lye should be done carefully. However, you can have fun making your soap in a variety of different styles. You should never use aluminum tools when working with lye because the lye will eat the aluminum and it isn't good for your soap. Stick with glass when possible. If you don't have a pan that you can mix them together in, then pour your oils/fats into a glass mixing bowl and then add your lye.

Lye Calculators: You have to have the right amount of water, lye, and fats/oils to make sure that the chemical process is complete. To assure that this is true if you make your own recipe or are trying one that you aren't sure that the recipe is as good as it should be, you can use a lye calculator (found online) to make sure that you have the right proportion of lye, water, and oils. Simply search "lye calculator" in your search engine. Add the oils and gats you are going to use. Then it will tell you how much lye and water you need.

Superfatting: It is also a good idea to super fat your soap with one or two tablespoones of extra oils or fats to make your soap more oil then lye. This will make sure there is no extra leftover lye in your recipe.

Beginners Recipe

2 Ounces of Sweet Almond Oil (measured by weight)

4 Ounces of Apricot Kernel Oil (measured by weight)

3 Ounces of Palm Oil (measured by weight)

4 Ounces of Coconut OIl (measured by weight)

3 Ounces of Palm Kernel Oil (measured by weight)

2.33 Ounces of Sodium Hydroxide (measured by weight)

6 Ounces of Distilled Water

Everything but your water is done by weight measurements because it is more accurate. You will then follow the soap making instructions (either hot or cold processes) and finish by adding colorant, frangrance (I prefer essence oil because it is all natural), herbs, or other additives. You can also add great things like aloe vera gel and vitamin E oil for great soaps that are good for your skin!


Another must have book for soap makers is The Soapmaker's Companion. There are a few different editions out there, but they are all fantastic. Whether you are just getting started or you want to know more natural ways to do things this is the book for you. It also has a great section on coloring your soaps in beautiful ways without using harsh dyes.


Making soap can be a lot of fun. Your whole family can enjoy the process and the results if you wish. It is a little pricey to get started, however supplies last a long time making it cheaper than regular soap most of the time. You have complete control and can use your soap for gifts as well as family use.


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  • SEXYLADYDEE profile image

    SEXYLADYDEE 4 years ago from Upstate NY

    Great hub Aiden. I love soap making hubs. I make hot processed soap in a crockpot and prefer to be able to use it right away. I have seen Youtube videos on making M & P by adding a lot of ingredients to make a base product and letting it cure and then "rebatching". I personally won't do it because most melt and pour bases are petroleum "processed" and I am making an all natural product for myself and others. Voted up!

  • aidenofthetower profile image

    aidenofthetower 5 years ago

    Little Lamby...

    If I understand you correctly you are starting with a standard melt and pour soap and adding lots of great and super skin healthy ingredients and then letting this be your new "base". If that is indeed the case then yes, it will make a soap that is very safe and also healthy for the skin. If you add too much shea butter, vinegar oil, and coconut oil you won't get very many bubbles. However, when you buy a melt and pour base it is already soap. It lacks any fancy ingredients, but it is in a state that you could use it right away.

    The reason you cure a soap is that you want to make sure that the lye inside of it has had a chance to combine with the oils and create the soap. If you are making soap using lye and oils and you are worried about there being too much lye you can do a process called "superfatting" which means adding a bit more oils then you need in order to make the soap. You can also test your cured soap by using pH paper or litmus paper. Lye will make the soap acidic and when it's all soap it will be slightly alkaline with a pH above 7.5.

  • profile image

    Little Lamby 5 years ago


    I am a beginner for soap making. I have been reading and researching on how to make safe to use soaps.

    Please let me know if this is one good way of making soap and if it safe to use soap made using this method.

    Cut and melt the melt and pour base in a pot. Once melted, let it to cool down until it is warm. When it is still lukewarm add add unrefined shea butter, extra virgin olive oil, unrefined coconut oil and goat milk. Stir it well until everything melts and mixes well. Then pour it into mould and cure it for 8 weeks. This is considered I am making the ‘initial melt and pour base’ for my soap.

    Then, as and when I want to make soaps, I will use this ‘initial base’ as my melt and pour base. I will cut and melt this ‘initial melt and base’ which I have cured. Add dye or colour, essential oils, fruit puree and honey. Then pour it into moulds and let it harden for 2-3 days. And it is ready to use.

    Please let me know if this method will work properly. And can I please know if this method is considered the hot or cold process?

  • aidenofthetower profile image

    aidenofthetower 7 years ago


    I have actually done the hot process soap on a number of occasions and with a lot of success. I once did a brown sugar and almond soap that was to die for. Great smell and an amazing feel to your skin. I never had a drying out problem. Hot process soap is also great for soap balls. As it starts to cool you can dip your hands in oil and actually roll the soap into balls while it is still warm. Feels great and you can have a lot of fun with it.

    I wouldn't recommend doing a hot process soap in an hour unless you will be curing it. The advantage to cooking it for six hours is that the soap making process is then complete and you don't have to worry about the lye not being soap yet.

    You can definitely link to my hub. Good luck and enjoy!

  • Dolores Monet profile image

    Dolores Monet 7 years ago from East Coast, United States

    Aiden, nice hub. I love to make soap and have written my own hubs about it. I have learned that you can make Hot Process soap in only an hour, though I've heard of the longer cook time as well. I think the longer cook time makes for a harder and more long lasting bar of soap but have yet to try it for fear of drying it out. Have you actually made the long cook HP soap? How did it turn out?

    (Hope I remember to check back)

    If it's okay, I'd like to link to this hub. Additional info is always good!

  • Mrs M profile image

    Mrs M 8 years ago from Ohio

    This was great! Your hub makes me want to go out and make my own soap right now. :-)

  • CennyWenny profile image

    CennyWenny 8 years ago from Washington

    Thanks, this is really informative and exactly what I was looking for.

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