Basic Slow Cooker Soap Recipe

Katie Wells Avatar

Reading Time: 6 minutes

This post contains affiliate links.

Read my affiliate policy.

Slowcooker Crockpot Basic Soap Recipe with coconut oil and olive oil
Wellness Mama » Blog » Natural Home » Basic Slow Cooker Soap Recipe

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!


Become a VIP member!

Get access to my VIP newsletter with health tips, special deals, my free ebook on Seven Small Easy Habits and so much more!

Easy Habits ebook on ipad

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.


323 responses to “Basic Slow Cooker Soap Recipe”

  1. Carmen Avatar

    This recipe uses 50% coconut oil and a superfat of almost 5%. Isn’t it too drying on skin? All the literature talks about the fact that a bigger percentage of coconut oil in soap requires a bigger percentage of superfat in order of keeping the soap appropriate for usage on skin.
    Did anyone try the recipe as it is? What was your impression?

  2. Stacy Neal Avatar
    Stacy Neal

    5 stars
    I’ve been making this soap for over five years. It’s the absolute best. My husband’s coworker was getting chemo treatments and this was the only soap she could use that didn’t irritate her skin. She had tried all different kinds of natural and organic soaps, no fragrance soaps and all of them really bothered her. I gave her a few bars of Wellness Mama soap to try and it was a game changer. I made it for her for years.

  3. Jenna P Avatar

    hi. I was looking to make soap for dogs and humans. Can this recipe be used on dogs or will I need to take out the Essential oils? I know dogs can be sensitive to essential. Is there any EO I could use in the soap for dogs or something else that can give it a nice smell?

  4. Jaime Avatar

    What temperature does the lye need to be at? Lots of recipes say the water and lye should be way be he same at 100 f, has anyone gad any issues? Thanks!

  5. Carmen Avatar

    I would like to know if you have any vegan coffee coconut oil and olive oil soap receipe would love to learn how to make soap for my personal use?

  6. Irene Delpree Avatar
    Irene Delpree

    I read your recipe and it sounds great! The only thing is that I would like to make liquid Castille Soap. Do you have to make first the bar soap? or can you do it directly liquid? please, I would appreciate it very much because all the recipes I have seen are for making bar soaps and I want it to come out liquid..

  7. Melissa Johnson Avatar
    Melissa Johnson

    I am looking forward to trying this recipe. I purchased lye over 2 years ago with the intent of soap-making, but have been intimidated by the lye factor. I don’t have a stick blender, can I just had stir it? Also, if I want to add oatmeal or lavender sprigs, when would be a god time?
    Thank you.

  8. Jo Avatar

    Thanks for the easy to follow instructions. I’m new to soap-making and searching for recipes and supplies now. Does your scale really measure to 4.844 oz? I’m researching scales and they don’t specify they measure to that small of a decimal. I know an accurate amount of Lye is crucial to the process.

    1. Augel Perry Avatar
      Augel Perry

      Try converting ounces to grams. (just google it) That will get you a more accurate measurement.

  9. Lea Avatar

    IF you have a vent over your stove. PLEASE turn it on & stir your lye/water there.
    I hate to see someone have a door slam on them carrying it in the house !!!!!!!

Older Comments
1 8 9 10
4.25 from 66 votes (48 ratings without comment)

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating