Lye is dangerous stuff. If you’ve ever thought about making soap (or lutefisk, ew) but have been too scared, allow me to assuage your fears. If lye were a Ghostly Gondolier who haunts Venice, I would be the Scooby-Doo team who shows up to reveal that the boatman is really just an loser who wants to steal valuable medallions. By way of a clumsy metaphor, I’m trying to say that understanding what makes lye so scary can be a great way to face your fears.
Tag: soap science
How Soap Gets You Clean
Now that you know how soap is made, let’s take a closer look at how it gets you clean.
Developing a Soap Recipe
When I was learning how to make soap, I felt completely overwhelmed by all the information out there. Some recipes are in ounces, others are in grams. Some throw in tablespoons and teaspoons for good measure (ha!). Superfatting is baffling. There are 937 lye calculators out there. Am I an evil person if I use palm oil?
My blog is my space where I sort through information and try to demystify DIY so today, I want to talk a little about developing recipes. I’ve been trying to think of a way to make soaping a little easier for people who don’t have the perfect sized mold or are missing an expensive oil but want to re-work the recipe into something they can use.
Like many good things in life, it all comes down to math. When you’re making soap, the difference between good math and bad math can be a really nice bar and one that burns your skin off. Not really a chance that most people are willing to take, I’m thinking. With all that in mind, this is a step-by-step guide to making your own soap recipe.
1. Determine the capacity of your soap mold in grams or ounces by filling it up with water and weighing the water. Don’t forget to tare the weight of the mold.
2. Calculate how much liquid and total oil you’ll need. This will be determined by what liquid you decide to you to dissolve lye. As a guideline, waters use a 1:3 water to oil ratio where as milks use a 1:2 ratio. Although this is a useful rough estimate, always use a lye calculator to make sure that your recipe will be safe.
- Waters (1:3 ratio)
- Beer (freeze first)
- Coconut water
- Milks (1:2 ratio, freeze first)
- Almond milk
- Cow’s milk
- Goat’s milk
Once you’ve chosen a liquid, you can move on in your calculations. I think best visually, so I use charts when I do the math. Let’s use one of my molds as an example. My mold holds 36 oz of water so I put that number in box A2. The recipe I’m using in this example uses water to dissolve the lye, so we’ll use a 1:3 ratio. That means that 75% of the oil/water will be oil (box B2). All that’s left to do is multiply across the row to find out how much water you’ll need in your recipe.
|2||Water||36 oz||25%||9 oz|
|3||Oil||36 oz||75%||27 oz|
3. Come up with your oil recipe. This is the science part. Check out my page on soap making lipids to make sure you’ve got the right balance of moisturizing, cleansing, hardness, and bubbles.
Note sure where to start? Try soap queen’s favorite recipes or tips for formulating your own recipe.
Here are some of my bases:
- Mamoot (1 august 14)
- 59% olive, 40% coconut, 1% shea
- Nice and hard, good bubbles, a little drying
- Mamoot (25 may 14)
- 70% olive, 20% cocnut, 8% avocado, 2% shea
- Nice suds, but melts quickly and took days to unmold
- The Nerdy Farm Wife (4 october 14)
- 68% olive, 25% coconut, 7% castor
- Very easy to cut and stamp, bubble and smooth
- Mamoot (10 december 2014)
- 30% olive, 30% coconut, 30% palm, 5% castor, 5% avocado
- Nice and hard the next day, easy to cut and stamp
- Mamoot (10 december 2014)
- 30% olive, 30% palm, 20% coconut, 5% sunflower, 2.5% castor, 2.5% avocado
- Still soft the next day, very hard to stamp and cut cleanly
- Mamoot (11 december 2014)
- 32% olive, 32% coconut, 32% palm, 4% sweet almond
To work with percentages in recipes, I use charts again. Let’s do another example. Remember how we found how out how much oil we’ll need in our sample recipe in box D3 above? Let’s put that number in each box in column G.
|2||Olive oil||67%||x 27 oz||= 18 oz|
|3||Coconut oil||26%||x 27 oz||= 7 oz|
|4||Castor oil||7%||x 27 oz||= 2 oz|
4. Run your oil recipe through a lye calculator to see how much lye you’ll need. I usually go for 5% because it’ll make a bar that’s not so soft that it melts in the shower but still in a safe level.
5. If oils are the science, this is the art part. Create a bar recipe by adding scents, exfoliants, colorants, and other additives. Unless the ingredient mentions otherwise, these parts are added after the soap has reached trace.
- Essential oils – Expensive, yes, but worth it in my opinion. They give crispy, unchanging scents and are easily predictable as to what they’ll do to the soap.
- Fragrance oils – Honestly, I’m not the biggest fan of fragrance oils. I’ve tried a few and they’ve all been so heady that I’ve had to leave my windows open for hours afterward to make my headache go away. I’ve also found that most smell very different in the bottle and after saponification. Plus they’re not much cheaper than essential oils.
- Citrus zest
- Coffee grounds – If you don’t think you’ve added enough, STOP. You probably have. Coffee grinds really are lovely in moderation but painful in excess.
- Oatmeal – Grind it up so that it doesn’t clog your shower drain
- Powdered or crushed nuts
- Seeds – poppy, chia, flax, cranberry, strawberry
- Tea bag contents
- Australian pink clay
- Australian red reef clay
- Brazilian red clay
- French red clay
- Moroccan red clay
- Red oxide
- Brazilian yellow clay
- Buriti oil
- Carrot Baby food – Only ingredients can be vegetable/fruit and water; to use, replace half of your liquid with baby food and combine it with lye at the beginning of the recipe
- French green clay
- Green oxide
- Zeolite green clay
- Alkanet root
- Brazilian purple clay
- Kaolin clay
- Titanium dioxide
- Bentonite clay
- Activated charcoal
- Australian black clay
- Pumpkin Puree – Replace half of your liquid with baby food and combine it with lye at the beginning of the recipe
- Clay – Provides slip; good for shaving soaps
- Dried flowers
- Honey – A humectant
6. Take notes. You’ll only get better as you make more soap so you might as well start noting now what works and what doesn’t.
Soap is the metallic salt of a fatty acid. What in the world does that mean? Well, in chemistry, salt isn’t just the white stuff that always hangs with the pepper, it’s any product that comes from neutralizing an acid and a base. Let’s take kitchen salt (sodium chloride) as an example. When you combine hydrochloric acid (HCl) with sodium hydroxide (NaOH), you get sodium chloride (NaCl) and water.
HCl + NaOH –> NaCl + H2O
This is particularly cool because hydrochloric acid is crazy acidic (it’s the stuff that your stomach uses to break down food) and sodium hydroxide is suuuuper alkaline (remember the scene in Fight Club when Brad Pitt burns that ugly hole in Edward Norton’s hand? That’s lye AKA sodium hydroxide) which means achtung, baby! Put them together, though, and you get two completely safe and consumable substances.
Making soap – or saponification, if you’re savvy – is pretty much the same thing. Add lye to an oil and you get a salt that we call soap! More specifically, you combine a trigylceride with lye and end up with soap and gylcerine.
C3H5 COOR COOR COOR + 3 NaOH + (H2O) –> 3NaCOOR + C3H3 OH OH OH
You already know what lye is, but what’s about triglycerides? As it turns out, all the oils we’re familiar with are different types of triglycerides. If you look at the formula for triglyceride, you’ll notice there are some R’s up in there. Those R’s stand for fatty acid radicals, three of which are combined to create a single type of oil. Olive oil, for example, is made up of two oleic acid radicals and one palmitic acid radical. Because of their chemical makeup, different oils and fats have specific properties that can be helpful or harmful in soap making. We’ll talk more about this when we get to the recipe.
The glycerin that’s a byproduct of the reaction is one of the best reasons to make your own soap. Glycerin is a humectant (a thing that keeps moist things moist) and makes your skin soft and moisturized. Often, store-bought soaps have been stripped of most of their glycerin, which is then sold to be used in more expensive bath products.