How to Make Cold Process Soap

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How to make cold process soap
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As the long-term effects of antibacterial soaps become more widely known, people are turning to more natural alternatives. This movement has resurrected the art of soap making. If you are new to making soap you are in for a real treat! It can seem like a daunting undertaking at first but it is such a rewarding process.

No farmer’s market would be complete without the beautiful array of homemade soaps. It is wonderful to support these local vendors but if the price-tag is out of reach for you, don’t despair. You can still ditch the antibacterial soaps by making your own homemade cold process soap!

How Is Soap Made?

Soap is a chemical reaction that occurs as a result of mixing an animal or vegetable fat with a base (sodium hydroxide). This chemical reaction is called saponification.

Merriam-Webster defines saponification as “the hydrolysis of a fat by an alkali with the formation of a soap and glycerol.” OK, so what does that mean?

Each fat has a unique combination of triglycerides. Triglycerides are compounds made up of a single molecule of glycerol and 3 fatty acids. Each combination requires a different amount of alkali to complete the saponification process. The alkali in soap-making is sodium hydroxide, also called lye.

The lye is mixed with water to create a basic solution. This solution is then mixed into your fats. As they are combined and begin to react, the glycerol molecule is separated from the fatty acids. The fatty acids then react with the hydroxide ions in the lye solution. This is saponification.

The two resulting products of the saponification process are glycerin, which is wonderfully moisturizing for the skin, and soap. No lye remains as it has all reacted with the fats to create a completely new substance.

Worried About Lye?

As I covered in-depth in this post, it isn’t truly possible to make soap without lye in some part of the process. Lye is the necessary agent for saponification and any true soap, even one you buy, is made with it. You can purchase a pre-made soap base but it is much less budget friendly.

Cold Process Soap vs. Hot Process Soap

The method you choose is a matter of personal preference. This post is to teach you about cold process soap but you can take the same recipe and use the hot process method instead.

Both of these methods begin in the same way. You make a lye/water solution and mix it with the oils to begin saponification. To make a cold process soap you would incorporate any additives and pour it into the mold as soon as it reached trace (more about trace later).

For hot process soap you would let the soap batter “cook” in a slow cooker on the lowest heat to accelerate and complete saponification. Then you would stir in your additives and mold it.

Cold process soap takes 4-6 weeks to completely saponify and be ready to use. In theory, hot process is ready to use immediately. However, it is wise to let it sit a week or so to harden a bit. This will make it last considerably longer.

I have made soap both ways and I like each method for different reasons. Cold process soap is easier to pour into the molds so if you are trying to use a mold with a design or pattern I would recommend cold process.

I like hot process for my everyday soaps (especially because I don’t always get them made on time, *ahem*), so it is great if I am in a pinch and need soap, like, yesterday.

Both methods are great and in the end you get the same result, soap! If you would like to try hot process you can try my recipe for basic slow cooker soap.

Ingredients for Making Soap

The most basic ingredients you will need are water (distilled is best), lye (sodium hydroxide), and some type of animal or vegetable fat (such as olive oil or tallow). These three ingredients are essential and it is wise to use a lye calculator to accurately determine the ratios needed for proper saponification.

There are countless combinations of oils you can come up with for a soap recipe. Each fat or oil has it’s own impact on your finished product. Some are great cleansers while others are more gentle and moisturizing. Some make large bubbles as opposed to others that create a low lather.

You can use all of one type of oil or a mixture of several different ones. A pure olive oil soap, also called castile soap named for a region in Spain, makes a very gentle bar of soap. A pure tallow soap has high cleansing ability and makes a great laundry bar.

I personally like to use at least two different oils to give the soap a bit more character. With a blend of oils it is much easier to achieve the qualities you are desiring in a soap.

Some of the most popular soaping oils are:

  • coconut oil
  • olive oil
  • castor oil
  • cocoa butter
  • mango butter
  • sunflower oil
  • sweet almond oil
  • jojoba oil

If this will be your first time making soap, a good place to start would be to use olive oil, coconut oil, and castor oil. This combination will give you a mild soap with a good lather and these oils are easy to come by. We will use these oils in the instructions below.

Optional ingredients can be added to customize your soap recipe. Essential oils added after trace are a natural option for giving your soap a lovely scent. Clays add a silkiness to the soap that is especially good for shaving. Sea salt soap (do not use dead sea salt) is exfoliating and detoxifying.

Ground coffee, oatmeal, and botanicals like dried lavender flowers or herbs give a nice texture to the soap. For a natural colorant you can try adding mica powders, cocoa powder, turmeric, or spirulina.

As you learn more about soap making you can even experiment with alternate liquids such as goat milk, herbal tea, or even beer.

Working With Lye

Lye is used to make all soap. Even melt and pour soap bases were originally made with lye. There is a common misconception that soap is not natural or healthy if it is made with lye. This simply isn’t true. It is necessary to use lye to achieve the chemical reaction, but you can be assured that when done correctly, no lye remains.

In fact, most soap is “super-fatted.” This means that there is extra fat worked into the recipe so that there is no possibility that any lye will remain. This also makes the bar more moisturizing. A good rule is to superfat by 5%.

I would guess that working with lye is the greatest deterrent for people who are thinking about making soap. I can understand how this would be a stumbling block but if you know and follow proper safety measures, you shouldn’t have any problems working with it.

Lye safety measures

  • Wait until children are in bed. Making soap is not an activity to do with children. Watch out for pets as well. Children and pets can cause distractions or spills.
  • Wear long sleeves and protective gear including safety glasses and rubber gloves.
  • Make sure your workspace is free of clutter that could cause a spill. Also, remove anything that could be ruined if a spill were to happen.
  • When the lye and water are mixed it will create fumes. Do this step in a well-ventilated area or even outside. I prefer to do it outside so I have no concern about fumes and then if I were to spill (I haven’t yet) it would not be in my house.
  • Always add lye to the water. DO NOT add water to lye. It will create a caustic eruption! The adage in the soaping world is “snow floats on the lake.” It MUST be done in this order.

Hopefully these safety tips serve to make you feel more comfortable working with lye. The first time is a bit nerve-wracking but once you have done it you will see that it is not so frightening!

Cold Process Soap Making

Now that we’ve got those little details out of the way, let’s get into the nitty gritty of soap making, and more specifically, the cold process method!

Soap Making Supplies

I have a set of tools I keep just for soap-making. It is not absolutely necessary to keep them separate but it eliminates any possibility of not getting your tools clean enough for food preparation.

  • Non-reactive pot or slow-cooker for warming oils
  • Heavy plastic pitcher or quart mason jar for mixing lye/water
  • Second jar or disposable cup for measuring lye
  • Infrared thermometer or 2 candy thermometers
  • Mold (this one will fit this recipe)
  • Digital scale
  • Stick blender
  • Spoon
  • Spatula
  • Safety glasses and rubber gloves
  • Lye – I have purchased lye online and also at a local hardware store. (Try a smaller store as the large chain stores do not typically carry it.) You will have to ask an employee for it.
  • White vinegar for final cleanup

How to make cold process soap
3.79 from 19 votes

Basic Cold Process Soap Recipe

Ditch the antibacterial soap and make your own beautiful cold process soap at home.
Active Time1 hour
Resting and Curing Time29 days
Yield: 12 bars
Author: Katie Wells




  • Prepare your mold. Wood molds will need to be lined with freezer paper or wax paper. Silicone molds are ready to use as is. You can also use any box if you line it with freezer paper, wax paper, or a thick garbage bag.
  • Put on protective gear, place a glass jar on the scale, and tare the scale.
  • Pour distilled water into the jar until it reads 12.54 oz.
  • Set aside.
  • Put a second jar on the scale and tare the scale.
  • Carefully pour lye into the second jar until the scale reads 5.09 oz.
  • In a well-ventilated area or outside, slowly pour the lye into the water.
  • Stir the mixture until the lye is dissolved. It will become quite hot so be careful if you need to move it.
  • Let this mixture sit and cool to between 100-120°F.
  • While the lye is cooling, measure all other ingredients EXCEPT the essential oils and warm them together in a pot or slow-cooker.
  • Once they are melted, remove them from the heat and let cool to between 100-120 degrees. I use the infrared thermometer about every 5-10 minutes to test the temperature. This works really well, but a candy thermometer placed in each container also works. If one is cooling faster than the other you can put your oils back on the heat source or the lye/water mixture in a warm water bath to slow the cooling process a bit. Ideally, you want the lye/water and the oils to both be between 100-120 degrees and within 10 degrees of each other.
  • When the temps match, slowly pour the lye/water into the oils.
  • BEFORE you turn your stick blender on, make sure the blade is completely under the mixture or you will splash it everywhere. Use the stick blender to bring the batter to a light trace. It should be slightly thick and resemble cake batter.
  • If using, add the essential oils now.
  • Blend essential oils in by pulsing the immersion blender a few times. This should bring the mixture to a medium trace. You can tell when you have reached a medium trace by lifting your blender up out of the mixture (in the OFF position) and observing how the drips behave. They should leave a trail or “trace” on the surface. If you don’t use essential oils, just pulse your blender a few more times to bring it to medium trace.
  • Pour the soap batter into your prepared mold, using a spatula to get it all out. Remember that the soap is not fully “cooked” yet at this point and could still irritate your skin so you should still be wearing your gear.
  • Put the mold somewhere it can sit for 24 hours.
  • Place an upside down cardboard box over the soap and cover with a towel. If your house is warm the towel may not be necessary.
  • Let sit for 24 hours.
  • You can now remove your soap and cut it. This recipe in the silicone loaf mold makes about 12 bars weighing approximately 4.5 oz each, but you can cut them whatever size you like.
  • Stand the bars up in a dry area with an inch or so of space in between to allow for air circulation and let them sit for 4-6 weeks. This will allow the soap to complete the saponification process. The soap will also lose some of its water during this time making the bar harder. The harder the bar, the longer it will last.


Soap Making Clean-up: 
Rinse the jars and any supplies that had lye or soap batter in them well, with running water. I have washed the tools two different ways. You can pour some vinegar in a sink filled with hot soapy water and wash them in there, or you can wash your well rinsed dishes in the dishwasher.

A Note About “Trace”

Most soap recipes tell you to blend the lye/water and oils together until you reach trace. What this means is that you will need to blend until there is no separation left in the mixture. If the lye/water and oils are not completely mixed, your oil will separate in the mold and leave pockets of lye.

When your mixture has reached a light trace it will resemble cake batter. A medium trace is more like pudding but still pourable, and a thick trace holds its shape. When you have gone as far as a thick trace, your soap will likely have to be spooned into the mold.

Have you made your own soap? Share your favorite recipe!

Ghee is a clarified butter made from removing the milk proteins from butter. It is a traditional sacred food in many cultures and has incredible flavor.

Katie Wells Avatar

About Katie Wells

Katie Wells, CTNC, MCHC, Founder of Wellness Mama and Co-founder of Wellnesse, has a background in research, journalism, and nutrition. As a mom of six, she turned to research and took health into her own hands to find answers to her health problems. is the culmination of her thousands of hours of research and all posts are medically reviewed and verified by the Wellness Mama research team. Katie is also the author of the bestselling books The Wellness Mama Cookbook and The Wellness Mama 5-Step Lifestyle Detox.


75 responses to “How to Make Cold Process Soap”

  1. Jessie Avatar

    I’d just like to comment on using wax paper to line molds: DON’T do it! It does not survive the heat from saponification. It’ll absorb, then leak, oil and when you finally get the soap out, it will stick like caramel to braces.
    Use baking paper, parchment paper, freezer paper, butcher paper, plastic shopping bags, garbage bags, corrugated plastic, Mylar sheets, silicon mats cut up to fit your mold, disposable chopping/cutting mats cut up to fit your mold.
    You get the idea. ? Just never wax paper. Or aluminum foil for that matter.
    Happy soaping!

  2. Christina Avatar

    Dear Wellness MaMa,

    I’m going to start making beer and wine soaps. Is this safe for children to use these soaps considering our skin absorbs a percentage of what we put on it?
    I will be boiling the beer and wine first to remove the alcohol and freezing it but just wondering in case my customers ask.

    Thank you very much

  3. Ayan Avatar

    Sorry if this is a dumb question, but once you open the container of lye, does it have an expiration date? Would it last for, say, four years?

  4. Geetha Avatar

    Can I add anything like dried rose petal powder,coconut milk in the cold process recipe.

  5. rez Avatar

    for the cold process recipe -I notice you use oz you don’t mean fl oz for oils do you?
    I thought that oz were for dry ingredients and not liquids, just bit confused.

  6. Tom Hall Avatar
    Tom Hall

    My mother used to make soap 70 years ago on the farm. She used only tallow and lye, just pouring soap into a pan and cut it into squares. It was quite strong and was used for washing clothes only.

  7. El Avatar

    I have never made any kind of soap before and I dont really need a big batch. Also to make a big batch its a tiny pinch in the pocket since i am only 17 haha. Can I half the recepie? Is it possible in soap making to half or quarter the recepie? If i make soap i would probabaly make only 2-3 bars. Also i have another question, is it necessery to have a stick bleander? If i make a very small batch of soap i think it will be difficult to immerse the bleander in comoletely and also currently i dont have a stick bleander. This was an amaizing post! Loved the instructions 🙂

    1. Rebekah Avatar

      You can make it without a sick blender but it takes for. Ever. To come to trace…with a stick blender were talking literally minutes and you’re done. Also this is an amazing recipe and really doesn’t make that much…plus you can stick a bar in your dresser drawer or hang them in your closet for a nice “sachet” until you need it! Good luck on your first batch…it gets easier and more fun each time!

  8. Debra Avatar

    Thank you so much! I’d really love to make a good salt bar for the kitchen sink. What types of Salt and how much do you recommend?

  9. Claire B Avatar

    I am very excited to attempt this! I was just wondering what kind of Olive oil? Extra Virgin or Light?
    Thank you again for posting this clear instruction!

    1. Jessie Avatar

      Use light olive oil, but read the labels. Some brands are sneaky and add other oils like palm, soy, or canola.
      It makes a difference when calculating the lye amount!

  10. Sue Avatar

    Hi. I have been using Melt an Pour soap and pouring it into animal mould for kids. If I use the Cold Pressed recipe, can I still melt this Cold Pressed Soap later in microwave, add my oils and colourants. And… When do I add Titanium Dioxide?

    1. Jessie Avatar

      Unfortunately, this isn’t a melt and pour (M&P) recipe. If you were to melt this soap, you would just get a very crumbly mess.
      To make M&P soap it would need to be hot process, require alcohol, glycerin and sugar as added ingredients in a very definite process.
      Check out some YT videos on making melt and pour soap or transparent soap. They should give you an idea of how you could do it.
      Good luck!

  11. Catherine Avatar

    Can’t seem to find info about the cutting. Do I still need to wear protective gear when I cut? Can I touch the soap with my bare hands after 24 hours?

  12. Kiki Peters Avatar
    Kiki Peters

    Thank you for such an interesting post! It was very detailed and easy to understand. I’ve always wanted to try making my own soap but has always had this fear factor which you were able to so easily put to rest. I am excited to try making my first batch. I have no doubt that it would turn out spectacular. Thanks Again.

  13. Michelle Yatsko Avatar
    Michelle Yatsko

    I am very excited to try soapmaking. I have successfully used many of your other homemade ideas. My question for this project is…. Can I cut the recipe in half? Do I cut the proportions exactly? Thank you so much for this page and all the things that you have taught this old lady.

  14. Amanda Avatar

    I love cold press soaps! They are so fun. I spent tons of money on soap making supplies until I finally found Bulk Apothecary. They have saved me so much time and money. I would recommend them to anyone.

  15. amy Avatar

    What can be used for natural colors in the soap? I’m not looking for a tan or brown shade. Would love yellow, lavender, pink, & green ideas!

  16. Vanessa Avatar


    I’m new to learning soaps. When I ran this recipe thru the soapcalc so I can learn how to use it, it gave me a measurement of 14.44 oz vs the 12.54 water and 5.15 oz lye vs the 5.09. What did I do wrong? I did the 5% superfat and the 38% water content

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