Using different oils and fats will give your soaps different properties. Learn how to harden, add lather, and improve soaps by varying the oils in the recipe.
Choosing oils for soap making isn’t like choosing oils for a homemade lotion or body butter.
When making our own cosmetics, we get so accustomed to using certain oils, that we want to use those oils in everything we make. I often get questions from people about switching out oils in a soap recipe because they like a certain oil better than the oil in that recipe.
Just because you love your homemade lotion made with 100% hemp oil, though, doesn’t mean that a soap made with 100% hemp oil is going to be great!
Saponification is a chemical reaction
When we make soap, we are completely altering the ingredients in a chemical reaction called saponification.
One of the reasons that some people are afraid to make their own soap is because they are afraid of using lye. Or, they are afraid that their soap has “lye in it.”
Lye is an essential ingredient in soap making. It reacts with the fats in your recipe to make a completely different material: soap!
Just as your finished soap will no longer have “lye in it,” the oils you used will no longer have the same properties.
What is lye? Can I make soap without it?
Yes, it’s possible to “superfat” a soap so that it arguably contains unreacted oils in it, but even in those cases, you probably can’t really tell that much of a difference what the “extra” oil is.
Soap oil properties
So, the oils in your soap will act differently than they did before the chemical process took place.
When you make a homemade lotion, you aren’t really altering the fats in the recipe. Yes, you do emulsify them with water, but that’s basically just suspending small particles of the oil within the water. It allows us to apply the oils and water together to our skin so that we can hydrate and moisturize it.
On the other hand, when you make soap, the different fats will act in different ways. Knowing the tendencies of the different oils and other fats in soap making will help us formulate an ideal soap bar for whatever our chosen purpose.
Solid fats tend to make hard bars
If you’re looking to make a hard bar of soap, choose a high percentage of solid fats. Solid fats are the ones that are generally solid at room temperature like coconut oil, palm kernel oil, or animal fats like lard and tallow.
Most liquid oils won’t make a solid bar of soap and need to be combined with a solid fat to make a decent, usable bar.
That said, olive oil is an exception. It takes a bit longer to harden up than the solid fats, but can harden into a decent, hard bar soap.
Oils in soap making
So, let’s explore how some of the more common oils behave in soap making.
Olive oils is one of my favorite oils for making soap. It’s inexpensive and provides a “conditioning” feel to the soap. That makes it a great oil for face and body soaps.
On the other hand, soaps made with only olive oil aren’t as cleansing and don’t provide much of a lather.
Soaps made with 100% olive oil are called pure Castile soaps. Some people, especially those with sensitive skin, love pure Castile soap because it’s gentle and not as drying as some other soaps. On the other hand, other people hate it. They think it feels “slimy” or are upset that it doesn’t provide much lather.
Pure Castile Soap
When it comes to liquid soaps, I haven’t found there to be the same issues. My pure liquid Castile soap actually does provide lather, and my liquid coconut oil soap isn’t as drying or harsh as I would have expected.
Easy DIY Liquid Castile Soap Recipe
Coconut oil is another one of my favorite oils for soapmaking. It provides a lot of lather and soaps made with coconut oil do a great job cleaning. I made my easy laundry soap with 100% coconut oil.
On the downside, soaps made with only coconut oil are said to be drying. That’s why it isn’t used alone in most soap recipes. You can , however, counteract that by superfatting by a large percentage, even to around 20%. (Superfatting is when you add more oil/fat than what is needed to make soap so that some unreacted oil remains in your soap.)
Easy Homemade Laundry Soap From Scratch, For Beginners!
As I stated earlier, when it comes to liquid soaps, I haven’t noticed the same differences that I’ve noticed with bar soaps. A bar soap made with 100% olive oil is completely different from a bar soap made with 100% coconut oil.
On the other hand, I have a hard time distinguishing the various liquid soaps I have at home. I’ve used my homemade liquid coconut oil soap in the shower for years now and don’t find it especially drying.
Homemade Liquid Coconut Oil Soap
Makes 1-2 Gallons of soap (See notes below.)
Castor oil can make a soap more easily dissolved in water. It also helps boost and extend lather time. That’s why it’s a great addition to shave soaps.
DIY Shaving Soap Recipe (& How to Use Shave Soap)
If used at too high a percentage (over 10%), though, it can make a bar of soap feel sticky. For most soaps, using up to around 5% is a good amount to use.
Castor oil can also work as an extra solvent when added to translucent soaps like glycerin soaps.
Vegan Glycerin Soap
Animal fats (Lard and tallow)
Animal fats make hard bars of soap with good cleansing abilities. You can make a good laundry soap with 100% lard or tallow. Normally, though, I suggest adding them up to 50% of a recipe to give a good stable lather.
In my first glycerin soap recipe, I used tallow to help make a hard bar of soap. When making glycerin soaps, solvents are used to remove part of the crystalline structure of the soap. That’s what gives the soaps a translucent appearance. If you don’t start with a hard bar of soap, the solvents would make a soft soap even softer!
Homemade Glycerin Soap Recipe (From Scratch)
Makes around 8 bars of soap.
For my peppermint holiday soap, I chose to add both coconut oil and lard to make a hard, white bar of soap. Because soaps made with hard oils also harden up quickly, I was able to make the peppermint candy design in a short time.
Laurel Berry Oil
Laurel berry oil is the oil that’s used together with olive oil in the traditional Aleppo soaps made in Aleppo, Syria. It may add a bit of lather to an otherwise low-lather Castile soap.
It’s usually added at around 20-40% of an otherwise pure Castile soap.
Laurel Berry Soap (Aleppo Soap Copycat Recipe)Check it out!
Liquid oils (Jojoba, avocado, sunflower oils, etc.)
Many liquid oils can be used up to 10-15% in soap recipes for medium lather and mild cleansing. When used in higher concentrations, the bar of soap can become too soft or the soap or can even go rancid prematurely.
Jojoba oil is really a liquid wax, but it mostly behaves like the liquid oils in soap making. It is more stable than them against rancidity.
When using liquid oils, it generally takes longer to reach trace during soap making. It also may take longer to harden up enough to unmold.
Butters (Shea, Cocoa, Mango)
Butters like shea butter, cocoa butter, and mango butter tend to help make hard bars of soap with stable lather. Using them up to around 20% of a soap recipe is a good amount to shoot for, but they can be used in higher amounts.
A tiny amount of wax, such as beeswax, can also help harden the soap. Too much, though, can completely kill the lather and make the soap sticky. Around 1-2% of the oil portion of the recipe is a good maximum amount to add.
To get the benefits of several different oils in a way that complement each other, most soaps use a combination of a variety of oils.
Liquid oils are used for their moisturizing and/or conditioning properties. They tend to make mild soaps, but if used alone, they can make bars of soap that are too soft. Olive oil is the exception and can make a hard bar of soap, albeit one that doesn’t lather much.
Some people love pure Castile soaps for their mildness. Other people hate them and say they are too slimy and don’t lather.
To help harden the soaps, increase their lather, and improve their cleansing ability, hard oils are added to the soaps. If you are using olive oil as the main liquid oil, only a small amount of hard oil is needed to improve the qualities of the soap. Otherwise, it’s good to shoot for at least 50% of the oils to be solid oils.
My easy beginner soap recipe is an example of what some call a “Bastile” soap. Bastile soaps are modified Castile soap recipes. They are mostly olive oil-based but have the addition of another oil/other oils. In that recipe, I added some coconut oil to improve the lather and cleansing ability.
That soap has become very popular. People love the simplicity of making a soap with oils that are very easy to find. If you’ve never made soap before, it’s a great place to begin your soap making journey!
Easy Basic Beginner Soap
Because that post was so popular, I based a couple of other recipes on it. They each were based on the same oil combination.
In my post with a recipe for pumpkin spice soap, you learn how to add goat milk to your soap so that it won’t be scorched. It also teaches you how to use a basic swirling technique to add a fun look to your soaps.
Easy Pumpkin Spice Soap
Another holiday soap based on that recipe is my gingerbread soap. It incorporates molasses for color and a mild boost in lather.
Easy Gingerbread Soap
Helping find the best combination
Once you know the basic tendencies of the oils in soap making, you can start experimenting with formulating your own soaps.
To do so, a lye calculator is a very helpful tool. It allows you to calculate how much lye to use in your recipe.
Soapcalc has a great lye calculator that can actually help you predict what your soap will be like. It will give you certain numbers for qualities like “hardness”, “Cleansing”, “Conditioning”, “bubbly”. The numbers may be confusing at first. If you click on the “view or print recipe” button, though, a new tab will be opened with all sorts of information about your recipe.
Next to the numbers for your soap’s qualities, you’ll also see a good range for each property. It gives you a guideline to shoot for. At first, you may want to stick to trying to get within the ranges for all of the properties. With time and experimentation, though, you may find that you like some soaps outside of those ranges. It’s all a matter of each person’s preferences, of course.
For more information about how to use a lye calculator, check out the following post…
very clear and good article easy to understand. Thank you
Thank you 🙂 easy to understand and simple writing makes me want to read it.
very simple explanation. i have just started dabbling in melt n pour soaps and want to learn cold process soap. thanks for such easy explanation and the recipes
Tracy Ariza, DDS
You’re very welcome! I wish you the best of luck with it!
Hello I am looking for a great base soap for melt and pour. I’m interested in making neem soap but I don’t know what would be best to mix it with. So far I’ve made a few to test with fresh neem leaves and glycerine soap base, coconut/mangosteen oil. Having washed with I can say it cleans well but doesn’t have a nice soapy lather. I feel like Id want a fattier soap base for this. I don’t know which one to use. Can you provide guidance please ? My goal is for the soap to have a nice foam later and be soft for sensitive skin since it is meant to combat psoriasis, acne, fungus etc. . Any help will be greatly appreciated. I feel like I’m running around in circles at all of the information but cant find anything precise to what I need.
Tracy Ariza, DDS
Check the ingredients of your glycerin soap base as many of them aren’t actually soap, but are instead syndet (synthetic detergent) bars. Regular soap doesn’t readily melt and pour smoothly like those soaps unless other additives are added to them.
I don’t have experience working with neem and soap, but if you are looking for a gentle soap with a lot of lather, you can play with adding some coconut oil to a soap that is mostly oils like olive oil that give a milder, more conditioning soap. (My beginner soap is like that. I have a second version in the notes section that adds a bit more coconut oil for more lather.)
If you prefer a glycerin type soap, I have 2 recipes up on the blog for glycerin type soaps (regular glycerin soap and vegan glycerin soap). They are pretty gentle and do provide a lot of lather.
The more lather you get, the more likely the soap is to be drying as the oils that provide the most lather also tend to make less conditioning soaps. You’re going to have to play with the ratios to find a good balance for what you are looking for.
Thank you so much. After a year now of soaping. I have clearer understanding of the oils and what they are used for. I have been to classes often it’s more around the use of lye and safety and very little about the properties of the soap. You have given me insight to the variance of oils and superfats and what they produce. I’m learning about differences between fragrance oils and essentials oils. You have the best information I’ve come across.. I’m looking forward to making some of your recipies.
Tracy Ariza, DDS
I’m so happy it’s helpful for you!
This post is great! I love olive oil (I actually use it on my skin from time to time) and feel it would be very moisturizing to use as a base for a bar of soap. Thanks for sharing!
Thank you very much for your information…I would love to take your class