A soap calculator is one of the most important tools you will use when creating your own soap recipes. In fact, you should run every recipe you try through a soap calculator just to be safe. A soap calculator will give you an idea of the basic qualities that your recipe will have, and the safe amount of lye to use.
Let's get into it! First things first head over to SoapCalc.net. There’s many sites that have soap calculators but I prefer this. At the top of their homepage click on Recipe Calculator.
Now, it's time to work your magic! On the webpage, you'll see a bunch of fields waiting to be filled with your soap-making secrets.
Step 1: Type of Lye
This will default to sodium hydroxide, leave it at that because this is the type of lye used for bar soap.
Step 2: Weight of Oils
This will be the total weight of your cured batch of soap. For a new creation I always make a 1 pound loaf first. That way I have enough to use for testing, but if something goes awry then I'm not wasting a large amount of oils.
Step 3: Water
This is where you select the percentage of water to lye used in your recipe. Lots of people use the Water : Lye Ratio but I have always used Water as % of Oils, it's just how the math in my brain understands easier. The default setting for this is 38% and that is for a hot process batch of soap. I am calculating for cold process, and the sweet spot for my recipes is at 30%. Extra water in a cold process batch of soap will yield more soda ash and glycerin rivers. It also will help keep your batter more fluid which helps with certain designs. I don't want to dive into water (pun intended😁) because that's a whole other rabbit hole. For the sake of this soap calculator demo, we are using Water as % of Oils at 30%.
Step 4: Super Fat
Super Fat refers to the extra oils in the soap that didn't bind with the lye. Basically, more oils and less lye = higher super fat. Too low of a super fat and your soap will be very drying on the skin. Too high of a super fat and your bar will be soft and mushy. The average amount used in bar soaps is between 5-10% super fat. I like it around 7% because it's a very moisturizing and nourishing bar, but still hard and doesn't dissolve too fast.
Step 5: Fragrance
What you enter here depends on what fragrance you are using. You can use fragrance oil or essential oils, and every single fragrance has a different percentage that is safe for skin use. You absolutely MUST do your research for this. For this recipe I am going to use Lavender essential oil which is safe in bar soap up to 33%. That's a huge amount, for fragrances safe in large amounts I like to use 1oz per pound.
We are skipping past Soap Qualities and Fatty Acids and I'll touch on that later, now it's time for the fun part! Choosing the ingredients!
Step 6: Oils, Fats, and Waxes
Select the ingredients you want to use from the drop down menu. Don't worry about the amounts yet, just get all your ingredients selected.
Click the Add button, you will see your ingredients listed on the right. Keep adding until every oil/butter/wax you're using is listed.
Step 7: Amounts
This is when you enter the percentage or weight of each oil. If it's a new recipe you're making then use percentages and make sure they add up to 100. If you already have a recipe and it's converted to weight then use the lb column.
Step 8: Calculate Recipe
Click Calculate Recipe and the weights or percentages of ingredients are calculated for you in both columns.
Now for the most exciting part, click on View or Print Recipe!
Your final recipe!
You can name your recipe at the top of the page, I'm calling this one Starter Soap Recipe because we are going to make it for my next blog post. There's a box at the bottom of the page called Additives, you can list any extra ingredients here like clays, mica, exfoliants, etc. There's also a Notes section where I usually just list what mold I used, and I'll make a note afterwards about how the soap batter behaved, how long it took to cure, and anything visual I notice after 24 hours.
Now to wrap things up, I want to touch on Soap Bar Quality. What do all these terms mean?
- Hardness: Hardness determines how long your soap will last. Aim for a higher hardness value but keep it in range to keep your bars firm and long-lasting.
- Cleansing: This property measures how well the soap removes dirt and oil from the skin. A higher cleansing value means a more effective cleanser, but be careful not to strip your skin of its natural oils! You want to be in the mid to low range to not dry your skin right out.
- Conditioning: Conditioning refers to how moisturizing the soap is. Aim for a high conditioning value for a luxurious lather that leaves your skin feeling super soft.
- Bubbly: Bubbly measures the amount of lather your soap produces. Higher bubbly values mean more bubbles – it's as simple as that!
- Creamy: Creamy measures the richness of the lather. A higher creamy value equals a decadent lather that feels gorgeous on your skin.
- Iodine: This property indicates the level of unsaturation in your soap, which can affect its stability and shelf life. Aim for a moderate iodine value to strike the perfect balance between hardness and conditioning.
- INS (Saponification Value): This magical number is calculated by combining the iodine value with the sap value of your oils. It gives you a comprehensive measure of your soap's overall quality and performance. Aim for an INS value in the 136-165 range for a well-balanced bar of soap that's gentle on the skin.
There you have it, that's your crash course on using a soap calculator. In my opinion it's a necessity in soap making to not only create but also to safety check recipes passed on to you. Now that we've covered equipment, safety, and using a soap calculator, you're definitely ready to make your first batch! I'm going to make this recipe and see it all the way through with you all, it's a good starter with oils that are easy to obtain. So follow me on my social media's listed below to keep up to date with new blog posts and more recipes.
Lindsay💜
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