Basic Slow Cooker Soap Recipe

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Slowcooker Crockpot Basic Soap Recipe with coconut oil and olive oil
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I’ve been fascinated with soap making for a long time. What was once a common household skill now seems like such a complicated process that many people simply buy soap instead. Unfortunately, many conventional soaps have additives, antibacterial ingredients and artificial fragrances.

Slow Cooker Soap Tutorial

I first started using homemade soap when I realized that it was the most cost effective way to get an all-natural soap.

I buy all ingredients in bulk so for under $10 I can make 12-18 big bars of organic soap. Store-bought alternatives cost 4-5 times that amount.

A Word About Lye

Many people are afraid to try recipes that use Lye, but I’ve found that much of this fear is based on misinformation.

Yes, Lye (or Sodium Hydroxide) is extremely dangerous by itself. It can cause skin damage, blindness (with eye contact) and death (if ingested). Lye in its pure form is something that can be very harmful and extreme caution should be used when using it in any way.

Lye is created through the electrolysis of sodium chloride (salt) and it creates an extremely alkaline substance. If added to water, it becomes sodium and hydroxyl ions and creates a strong exothermic (heat creating) reaction. Flashbacks to high school chemistry anyone?

Moving on…

When Lye is used in soap making, it is what is called a reagent, meaning it is used in a chemical reaction to create other substances. In soap making, a carefully measured water/lye mixture is blended with natural oils in a process called saponification. Lye is simply an agent used to create soap from oils and water.

There is no unreacted Lye remaining in properly made soap. If you’re considering making soap, definitely use extreme caution with unreacted lye and use a soap calculator to make sure you are using the correct ratio of water/lye/oils but don’t be afraid of this age old process.

Where to Find Lye: Some hardware stores carry Lye (sodium hydroxide) though many have stopped carrying it. I wasn’t able to find it at any of our four local hardware stores so I ordered this one online. If you have a local (not big brand) hardware store they might also be able to special order it for you.

Hot Process vs. Cold Process

As the name suggests, the difference between these types of processing is if heat is used or not. With both methods, a water/lye mixture is used and oils are used. The two are mixed together in the process of saponification.

With cold processing, the water/lye mixture is mixed with the oil mixture and the resulting mixture is poured into insulated molds.

Hot processing adds an additional step of “cooking” the mixture which speeds the saponification process and makes the soap ready to use in days instead of weeks. Both methods work and I’ve done both, but the hot process method is much faster.

Choosing Ingredients for Soap Making

Crock pot soap ingredientsThe advantage to making soap at home is that you can use high-quality organic ingredients and still get organic soap for much cheaper than store bought options.

In this basic recipe, I used organic Coconut Oil and organic Olive Oil, though any natural oils can be used. Use this Soap Calculator to figure out how much Lye and water are needed for whatever type of oils you want to use.

Really- the world is your oyster when it comes to picking ingredients but some popular and favorite ingredients are:

Once you’ve picked your ingredients, head over to the calculator and find out how much water and Lye you need.

For this specific recipe, I used an equal mix of olive oil and coconut oil, but just pure coconut oil can be used (like this great recipe from Mommypotamus) or just olive oil can be used. If just olive oil is used, you’ll have a pure castile soap (named after that region in Spain) which is very moisturizing but can take longer to cure.

Cocount Oil and Olive Oil soap

Gathering Equipment

How Soap should look before Turning off slowcookerI personally keep separate equipment to use for soap making. I found all of my equipment at a thrift store and keep it in the garage with the soap making ingredients.

Every source I’ve seen says that it is fine to use regular kitchen equipment for soap making as long as you wash it carefully afterward (see my notes at the bottom of this post on that). At the end of the process, you are just dealing with soap, so it isn’t toxic, but cleanup can be messy. To simplify, I just keep separate tools for soap making.

I have:

Slowcooker Crockpot Basic Soap Recipe with coconut oil and olive oil
4.25 from 66 votes

Slow Cooker Soap Recipe

This basic soap recipe uses coconut oil and olive oil and is made in a slow cooker. A simple and moisturizing recipe you can make at home!
Prep Time45 minutes
Active Time35 minutes
Resting Time1 day
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. I’ve heard of people using empty Pringles containers, but haven’t tried it.
  • Make sure that your work area is clean, ventilated and that there are no children nearby. This is not a good recipe to let children help with since lye is caustic until mixed with water and oils.
  • Weigh out 16 ounces of olive oil and 16 ounces of melted coconut oil and pour them both into the slow cooker.
  • Turn on high just until the oils heat up and then reduce to low heat.
  • While oils are heating, carefully measure the lye and water separately. TIP: This is the only thing I ever use disposable plastic cups for. They don’t weigh anything on the scale so they make measuring easy. I keep three separate cups labeled “Water”, “Lye”, and “Oil” to use for this purpose only. I reuse them each time so they aren’t wasted and I don’t worry about anyone drinking out of them since we don’t usually use these types of cups.
  • Carefully take the cups with the measured water and lye outside or to a well ventilated area.
  • Pour the water into a quart size or larger glass jar.
  • With gloves and eye protection, slowly add the lye to the water. DO NOT ADD THE WATER TO THE LYE (this is really important).
  • Stir carefully with a metal spoon, making sure not to let the liquid come in direct contact with your body.
  • As you stir, the mixture will become white and cloudy and get really hot. Let this mixture sit for about 10 minutes to cool. It should become clear when it has cooled.
  • When the oils in the slow cooker have heated to about 120-130°F, slowly stir in the water and lye mixture.
  • Quickly rinse the container used for the water and lye mixture out in the sink. I rinse well and then re-rinse with white vinegar to make sure all the lye has been neutralized.
  • Use a stick blender to blend the mixture in the slow cooker for about 4-5 minutes or until it is opaque and starting to thicken.
  • Cover and keep the slow cooker heat on low to thicken. I set a timer for 15 minutes and check it every 15 minutes until it is ready. It will start to boil and bubble on the sides first. After about 35-55 minutes (depending on the slow cooker) it will be thick enough that the entire surface is bubbly and the sides have collapsed in.
  • Turn the heat off and remove the inner bowl of the slow cooker.
  • If you are going to use essential oils for scent, add them now. I added lavender and orange.
  • Quickly and carefully spoon the mixture into the prepared molds.
  • Cover the molds with parchment paper and set them in a cool, dry place.
  • After 24 hours, pop the soap out of the molds. It can be used right away, but I prefer to let it set for a few more days so that it lasts longer.


Clean-up Tips
As I mentioned, keeping separate tools for soap making simplifies the process since things don’t have to be cleaned enough for food use. I still clean all tools carefully with dishwashing soap and water and rinse with vinegar just to be sure.
Since we are making soap, I typically soak the crock from the slow cooker with all tools in it for 8+ hours to dissolve and use the soapy water to help clean all the tools.

Ever made soap? How did it go? Share your favorite recipe below in the comments!

This basic soap recipe uses coconut oil and olive oil and is made in a crockpot or slowcooker. A simple and moisturizing recipe you can make at home!

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.


322 responses to “Basic Slow Cooker Soap Recipe”

  1. James Avatar

    I wouldn’t recommended using a hot process using olive oil as heating olive oil is extremely damaging to olive oil and creating a lot of free radicals in the oil. Unfortunately many people think olive oil is good to cook with and it is not as you create a lot of free radicals that can tax the immune system.

    For a hot process I would recommend all coconut oil and no olive oil

    For a cold process, olive oil is great, however, there’s a lot that can go into in evaluating whether one has purchased good olive oil and whether it’s been handled properly (in the USA companies are not required to use 100% olive oil to be labeled olive oil).

      1. James Avatar

        Thanks for the link, and I’m glad you wrote on olive oil, and I found it very informative. Many soap makers, even professionals and companies, unfortunately mishandle or improperly store their ingredients.

        Luckily we have concerned people like yourself out there doing research and attempting to inform the public on health issues.

  2. Stephen Avatar

    5 stars
    I used this recipe and directions to make soap for the first time. It was super easy and the soap works great! The only issue I had was once I was through cooking the mixture, it was difficult to spoon it into the molds, getting it to settle down into the molds. It was like trying to fill in a space with cool whip. Did I cook it too long (1 hr) or maybe did I get the mixture too thick when blending?


  3. Corinna Avatar

    Has anyone ever used a soap kettle? I saw one at Michaels and with a 50% off coupon it is not that expensive but all I read about it is to melt glycerine soap in it etc. Is it recommended to make soap from scratch with lye, coconut and olive oil etc.? I want to spare myself searching second hand stores for a slow cooker…

  4. David Avatar

    5 stars
    Just a funny observation in your article. You really should be nicer to your molds… “the resulting mixture is poured into insulted molds.”

  5. Marissa Avatar

    Hello! I am interested in making soap as wedding favors! I have never done it before but it seems rather cost effective and thoughtful! Has anyone made a lot of this recipe before? Any tips? I am thinking of making it in a loaf form, does anyone have any tips as to cutting it?
    Thanks in advance!

  6. Lonna Avatar

    I have made this recipe a handful of times (which I love your recipe, thank you for sharing), but was distracted this last time I made it. I poured the contents into the molds and it looked a lot oilier than normal. I’m thinking I didn’t let it cook long enough. Will it still work out or did I just waste a bunch of ingredients?

  7. Melissa Avatar

    Hi Katie, I tried this recipe and the soap didn’t harden as much as I thought it should. After putting into the mold I let it set for 24 hours and then it was hard enough to cut into bars. I let it sit for a few more days before using it. I cut the bars about 1 1/2 inches think but a bar only lasts about 5 days after starting to use it. Organic soaps I’ve bought are much harder and last longer. Any ideas? Thanks! Melissa

    1. Susan Avatar

      I wonder if you didn’t let it cure long enough. Set it aside for a few weeks and then try using it again.

  8. Vikki Avatar

    Can you substitute any oil for the coconut oil? I am allergic to coconut oil and it is hard to find natural soap and shampoo recipes with out it.

    1. Jason Avatar

      Yes you can substitute any oil. Some perform better than others but you can use all olive oil if you like. You could substitute lard or tallow as well from pork or beef. I would suggest finding an alternative this is also hard at room temp but pure olive oil soap is supposed to be really nice.

      Good luck!!

  9. Monique Avatar

    After reading all the info, do you really have to put Lye. What would happen if you didn’t. Thanks

  10. Katie Avatar

    Maybe I missed this detail, but how many bars on average does one batch make you?

  11. Bethany Avatar

    I made a batch of soap by myself for the first time and it separated! What did I do wrong?

    1. Susan Avatar

      When did it separate? After you put it in the molds? Is that what you mean?

  12. anna Avatar

    Hello, to whom it may concern, I am from Australia (Melbourne) were can I buy your organic soap made from coconut oil
    and olive oil, I disagree soap made from palm oil, I don’t like soap from palm oil at all. Please can you tell me were can I
    buy your products. Thank you.

  13. Susan Avatar

    I’ve been thinking about making my own soap for awhile now but, frankly, I was scared. I read so much information online and it sounded dangerous! I put it off for another six months.

    Reading this page, however, really made me determined to try making it. I went out yesterday on a shopping spree and bought everything I needed.

    Last night I made TWO batches of soap and it couldn’t have been easier. I measured carefully and slowly……..and did not rush anything. Easy peasy!

    This morning I rushed downstairs to check my soaps and they look great. I couldn’t help myself, though, and had to cut off a piece and headed straight for the shower, lol.

    I love it, thank you! My advice to others? Read lots, don’t hurry, and be careful. 🙂

  14. Dana Avatar

    Okay. So the link to the soap calculator is going to help me a ton!! I think that will answer my previous question. 🙂

    Thank you!

  15. Dana Avatar

    Hi Katie.

    I am ready to try making soap this year! I was curious if I could use just lard/or beef fat for all the oil portion and do everything else the same?

    I have all the ingredients either way. I would just like to do something with the fat! I saw a lady using beef fat at a Pioneer Days event we went to and she was making lovely soap. I even bought some that she had made weeks earlier. It was great.


  16. Lina Avatar

    Lye in itself is toxic, that is correct. Nevertheless it is used for baking in a very diluted form. The heat of the oven fuels a chemical reaction with the dough and the end product, like soap, is perfectly harmless and can be eaten without problems. Some kind of pretzel is made that way.

  17. Susan Davis Avatar
    Susan Davis

    I used to make a lot of my own soap, and often used it for the laundry. I poured it about an inch deep into a shallow box lined with waxed paper and let it cure. When it was set and firm but not hard, I would cut it into bar size blocks, and left it in the box for more curing. After it became hard enough for grating, I would grate it with an attachment to my mixer, then store it in zip lock bags. It did not dissolve as easily as commercial laundry detergent, so it was important to use warm or hot water, add the soap to the tub of water, and agitate to dissolve the soap before adding the laundry. Otherwise, it was great!

  18. Susan Avatar

    Lol….this brings back memories….I was making soap 25 years ago when my kids were small and we were raising goats. Yes, you can use this for laundry soap, but you need to leave it dry for a couple of weeks (or longer), then grate it down, and mix 1/3 soap flakes, 1/3 borax, and 1/3 laundry soda. I still make my own laundry soap, but I buy the soap now. Hmmmm…..may pop by the thrift store and pick up a slow cooker ;-)……. I used to use the 500ml and 1000ml milk/cream containers for molds… up the tops and pour in the soap. Once it’s ready you just peal off the container.

  19. Erin Avatar

    I haven’t tried making soap yet. A little nervous but going to go for it. Do you recommend anything to add for an exfoliating factor? I am looking to make something like the Kiehl’s Ultimate Man Body Scrub soap for my husband. Just discovering the world of natural living and
    I am loving your website- thank you!

    1. Anita Avatar

      Maybe you’re thinking of lime water, used in pickling and other foods. That’s calcium hydroxide.

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