How to Design Your Own Soap Recipe
This post may contain Affiliate Links. Thank you for your support!
Being able to design your own soap recipe is fantastic!
You are no longer inhibited by someone’s else’s ideas, favorite oils to use, or even batch size amounts. Instead, you make all the decisions.
Want a large 36 bar, 9 pound batch? Great, start designing.
Want to use the oils you have in the house and not have to go searching for an obscure oil? You can do that!
Designing your own soap recipes is not only fun and creative, it’s practical and very helpful if you are trying to be frugal.
Knowing how to design your own soap recipe also gets you ready to make adjustments to other people’s recipes. I get questions almost every day asking how to tweak a recipe. People want to make it smaller or larger, want to substitute one oil for another. I also get questions asking if they can make soap without the lye. Knowing more about how recipes are designed helps you understand what you can and cannot do (e.g. you can’t make soap without lye, only redesign it.).
Now that we’ve discussed the benefits and practicality of having the knowledge to be able to design your own soap recipe, let’s jump into it!
If you’re just getting started making soap, then you first need to understand the basics. Get my book Natural Soapmaking Book For Beginners, and head over to my Step by Step Lye Soap for Beginners page to get a handle on what’s happening chemically when you make soap, as well as what is involved in making soap from beginning to end.
I will get into the how-to of soap making a little bit here, because to design your own soap recipe, you need to understand what is happening within the soap making process.
You Can’t make Soap Without Lye
You need lye and oils to make soap. They come together in a saponification process (a chemical reaction) that basically busts oil molecules apart and forms new bonds which create soap.
Don’t be afraid of lye. Just don’t touch it and don’t breathe the steam in when you pour the lye crystals into the water. The steam dissipates after a few minutes and the lye water can be brought back inside or left out to cool.
Just be careful not to leave it around children or pets. We had a puppy that was supposed to be kept inside, but someone let out. She ran right up to a bowl of lye water that I was letting cool and took a big lick before we could grab her. She immediately started shaking her head and jumping around. It was horrible! She was already 50 pounds but I was able to grab her up and run her to the sink where we flushed out her mouth. She’s fine, but it really was a horrible experience. Yet, with the hundreds and hundreds (and hundreds) of batches I’ve made, I’ve never had any other accident. The only time I’ve had lye touch me is when making soap and a tiny bit of the batter splashes out onto my hand. You feel an itch and go wash your hand. That’s it. Or better yet, wear gloves until you’re done.
Don’t be afraid to use lye. Just be careful, just as you would using other chemicals you have around your house.
This is an important question!
Each recipe needs to have enough oil to use up all the lye in the chemical reaction. In the “olden days” people passed down recipes or they had to add up how much lye it took to use up all of a certain kind of oil because you need different amounts of lye for different oils!
Too much lye and the oils are all used up and your soap has lye leftover. Leftover lye is unhealthy for your skin (Stings, tingles, burns, yeah not good. So watch it when you see sodium hydroxide on your foot cream when it’s not used in a saponification process. Using it to burn off your foot layers is not healthy.)
How do you know you’re using the right amount? Use a lye calculator! When you substitute oils, unless you’ve done it a lot and already know the answer, run it through a lye calculator so you know there wasn’t a change.
What Does Too Much Lye Look Like?
You’ll know if you have too much lye in your soap, because it will be chalky and crumbly (literally fall apart in your hands in crumbles). Or if you haven’t stirred it enough, your temperatures were too cold, or you’ve used a toxic ingredient like fragrance oils, you may have “lye rivers” where the lye water hasn’t incorporated into the oils and it runs out of your soap as liquid.
Superfatting (or lye discounting) is the best way to ensure that you have exactly what you need for the type of soap you are making. Superfatting is the term used for left over oils in your soap after all the lye is “used up”.
For a laundry soap, I like to use a low superfat amount of 2%, because I don’t want a lot of oils left over to gum up my clothes and washing machine.
For body soap I like to use 5-10% superfat. This is a great amount that doesn’t dry out the skin.
For facial bars, 15-20% makes for a cleansing, but nourishing and moisturizing bar.
Shampoo bars seem to do best around the 5-15% depending on your oils and hair needs. If you have very oily hair, then more oils don’t always work very well.
Water in Soap Making
Water is used to dissolve the lye and help it to emulsify with the oils when blending. The standard percent of water to total oils in your recipe is 38%. I like to use closer to 34-35%. Some of that water needs to evaporate so your bars become hard. Lowering the water amount helps that process along. Most lye calculators will let you adjust this amount.
You can substitute goat milk or cow milk for ANY amount of the water in your recipe. If you make a recipe and it calls for 12 ounces of water in the lye calculator, then all 12 can be goat’s milk, or you can only substitute 6 so that you use half water and half milk. The reason that some people may not substitute the entire amount is twofold:
- Milk can scald easily, and if it does your soap will be very dark.
- Milk has sugars and sugars cause soap to heat up. If you’re already using hot oils like clove or cinnamon then adding milk and other sugars like honey may make your soap overheat if not watched very carefully. If you don’t want the worry, then substitute half instead of the whole thing.
The Benefit of Oils
Just like lye, oils are needed to make soap. The lye and oils come together in a chemical reaction to make soap. A variety is needed. You can make a fantastic soap with three specific oils but knowing which oils you need is important.
Castille soap has become popular over the past few years, but in reality, olive oil doesn’t make the best of soaps. It doesn’t harden well so it doesn’t last long, and it has very little bubbles or cleansing ability. Maybe that’s what you want; it’s a gentle soap that doesn’t remove many oils but helps to slightly cleanse the body. It’s a great soap for babies for that reason.
Some oils are higher in vitamin A, others in vitamin E. Learn about your oils if you have certain needs or desires you want to achieve with your soap.
To learn more about oils and their soap making properties, click here. That page has a chart on common oils used in soap making and what they bring to a soap recipe.
Which Oils Will You Use?
If all the knowledge about oils is overwhelming, just stick to using a lye calculator and playing around with oil amounts until you get the desired result. That may sounds nuts, but the more you do that, the more you’ll learn which oils make your soap more bubbly, make a creamy lather, make the soap harder, add moisture. So if all else fails, play with a good lye calculator.
A good rule of thumb is to have both liquid and hard oils. Varying oils brings multiple characteristics to the soap, as well as insures that you have a hard and bubbly soap. Using all liquid oils can sometimes (not always) make the soap softer and longer to cure. Using tallow, cocoa butter, shea butter, lard, beeswax, or coconut oil will create a harder bar.
As a cheat, and if you’re not vegan, keep in mind that the three oil beginning standpoint is:
- coconut oil
- olive oil
- lard (or tallow).
These three will give you a hard, bubbly, moisturizing bar.
If you’re vegan, then you may have to use some extra oils to get the same effect, but a good shortcut, starting point to play with is:
- coconut oil
- olive oil
- cocoa butter
Check out Soap Making Oils and Their Properties for more information on oils.
How Much of Each Oil
So now you have an idea of what oils you want to use, but how much of each? Where do you start?
What size batch do you want to make? Honestly, I have a general idea of how much I need and I just plug in amounts into the lye calculator and then calculate it. If it says that’s too much then I just shave off a few ounces here and there. After you make a lot of soap, this becomes an easy way to do it. You do not have to do it like that though. You can definitely start by counting your ounces up to the amount desired.
Another way to start is by choosing larger amounts for your bulk oils (olive, coconut, rice, cocoa butter, mango butter, canola) and less of oils you usually use less of (shea, argan).
A third way to begin is by choosing the same amount of each oil, plug it into the lye calculator, and then adjust.
- If there’s too much cleansing, lower cleansing oils like coconut oil.
- Not enough bubbles, add castor oil and honey.
- Not enough hardness, lower liquid oils and add more hard oils.
- Don’t use a large percentage of shea butter, as that can make the soap slimy feeling.
You’ve decided on the superfat content, the oils to use, and you’ve put them all in a lye calculator and found the perfect amount. What about the extras?
I call the following extras, because they don’t come into play in the initial stages of designing your recipe. They’re the second stage beauties that make your recipe amazing.
- Essential oils – Use essential oils instead of questionable fragrance oils. They often are the cause of soap going wrong.
- Herbs and clays for coloring – learn more here and here
- Exfoliants like oats or coffee grounds
- Honey – Honey is a sugar and sugars cause soap to heat up. It adds great bubbles to your soap, but watch the batch so it doesn’t overheat. Don’t insulate as much.
- Fruits, veggie puree – whatever puree you add to the oils as they’re cooling, remove that same amount from your water total. If I add 8 ounces of pumpkin puree to my cooling oils, then I will remove 8 ounces from my water total before pouring the lye into it.
- Alcohols –If you want to use Champagne, then let it sit out for 24 hours so that there are no more bubbles before use. Also, alcohols add sugars so don’t insulate. Some people even put their wine or Champagne soaps into the refrigerators after pouring.
With all of the information together from above, you should be able to start putting it all together.
- Superfat amount.
- Oils you want to use (be open for change if you find the recipe is too soft or doesn’t have cleansing).
- Extras you want to use.
Once you’ve jotted down those ideas, head to the lye calculator. My favorite to use by far is on soapcalc.net.
When you open this website, click on “recipe calculator” in the menu at the top.
You’ll have 5 things you can change to get ready: Type of Lye, Weight of oils, Water, and Superfat and Soap Qualities.
You don’t need to mess with type of lye unless you’re using KOH to make a liquid soap. You also don’t need to touch soap qualities as those are pretty standard.
I change weight of oils to ounces (though obviously choose grams if that’s what you work with). I then change the water amount from 38% to 35% (You can leave this alone if you want to). Then I change the superfat content if needed. The default is set at 5%.
Now you’re ready to put in your oils and amounts. Choose oils from the list and click add and then put in the ounces you want. Click “calculate recipe” at the bottom and then “view and print” right under that. This will open a new page that will show you your totals, recommended lye and water amounts, and fragrance amounts.
It will also show you how hard, bubbly, moisturizing, etc your soap will be. The INS number is a standard that was developed and is not something to die over. If your recipe falls within the range of the other categories then you’ll end up with a great bar of soap.
What have I left out? Have more questions? Don’t hesitate to ask. I don’t mind answering questions and love that more people are jumping into this age old skill.
If you’d like to jump off of a recipe that is already made, then check out these soap recipes to get started:
- Holiday Soap Recipes
- Christmas Soap Recipes
- Shampoo Bar Recipes
- Fall Soap Recipes
- Rose Soap Recipe
- Acne Detox Soap Recipe
- More Soap Recipes