Show Me the Suds! - Why soap lathers and why it doesn't

Here at Fat Chance Farm I make 100% animal fat soaps. That means that there's no coconut oil, palm oil, olive oil, shea butter or any other plant derived fats and oils. There are two big reasons for that, which are sustainability and skin care.

Sustainability

I live in northern Vermont and want to use local ingredients in my soap both to reduce the distance my various ingredients have to travel and to support my local community. As you might guess, there are not many coconut or olive trees up here! Animal fats are also somewhat of a by product of our many small pastured pork and grass-fed beef operations, so buying animal fats from local farmers helps them make money from what is often a waste product. 

Skin Care

The second reason is that there are a lot of people who love how animal fats make their skin feel! I've heard many success stories from people who have seen big improvements in various skin ailments, simply by adding tallow and lard products to their skin care routine. I myself have sensitive, easily irritated skin that sees a lot of hard use in my roles as a farmer and ski instructor. Tallow and lard keep it in tip top shape!

Different fats and oils impart different qualities to a finished bar of soap. While tallow and lard do a good job of bringing qualities like longevity (the hardness of the soap) and moisture, one aspect where they fall down a bit is creating big fluffy suds. Tallow and lard make a denser, creamier lather.

More Suds = More Clean... right?

This is a bit of a misconception that many people have about soap. Suds must be a direct reflection of cleaning power, right? Well, no, not really! The cleaning action of soap is happening down on a molecular level as the components of soap interact with dirt and bacteria on your skin, allowing them to be washed away by water. The fluffiness of the lather doesn't change that process (more on the one exception - hard water, below). In fact, more lather typically indicates that more soap is being rubbed off the bar and getting washed down the drain. The more lather, the more of your soap bar you're using up at a time!

So the dense, creamy lather of animal fat soaps does just as good a job at cleaning as plant oil soap and the bar will last longer. Sounds like a win win to me.

More lather, please!

If you would still rather see some more suds from your tallow and lard soaps, here are a few tips to get the bubble going.

• Use warm water - Cold water just does not excite the bubbles like warm water does. Be careful using hot water though, as excessive washing in hot water can dry out the skin.
• Use a soap bag - Soap bags or loofahs can do a great job of making bubbles in the bath or shower. Did you know we sell a natural sisal soap bag?
• Look for honey, maple or milk soaps - Anything that contains sugars can help increase suds in the finished soap bar. Our Honey Soap and our Milk and Maple Soap are both tops suds performers.
• Soften hard water - more on this below, but in short, the harder your water, the less your soap will suds AND the less effective it is at cleaning. This is the one time where lack of lather does reflect on the cleaning power.

Hard Water

The concentration of minerals in your water can also affect how well soap lathers. Water with a high mineral content (more than 61mg/L of calcium carbonate) is considered "hard" while water with less minerals is considered "soft."

When you use soap with hard water, the minerals in the water react with the soap anions to create the hard to remove mineral deposit known as soap scum. Hard water makes cleaning in general more difficult, since it makes soap less efficient, leaves spots on dishes, and residues on clothing, in pipes and on water fixtures. 

The big overall solution to hard water is to install a water softening system but that's not realistic for everyone and may not even be worthwhile if your water is only moderately hard. An easier solution is to use soaps that have hard water in mind, which means we need to talk about citric acid.

Citric Acid in Soap

Citric acid is a simple, natural ingredient that can help soap lather and clean better even in hard water. Instead of the minerals in your water reacting with the soap and creating soap scum, the citric acid binds to the minerals and lets them wash right down the drain. That leaves your soap molecules free to suds and clean as they were meant to!

What citric acid doesn't do is lower or significantly change the pH of the soap bar. Soap must be very basic (high on the pH scale) in order for the saponification (soap making) reaction to take place. Products that are "pH balanced" or have a "neutral pH" are not soap. They are more likely another type of cleanser or detergent that is made with a very different process than soap.

In fact, when creating a soap recipe that includes citric acid, I need to calculate how much of my base (lye) will be neutralized by the citric acid, so that I can add more lye and maintain the pH necessary for the soap making process.

Citric Aid Production

If you don't want to get into the nitty gritty of how citric acid is made, feel free to skip this section. TL:DR, citrus fruits are actually a pretty terrible source of citric acid (ironic, I know) and it's far more efficient to make it with chemistry.

So am I going to start adding citric acid to all my soaps to improve lathering for folks with hard water? Well, here's the issue: because citrus fruits are actually a pretty dilute source of citric acid (the highest concentration found is typically only 8% and 5% is more average) a different way to manufacture citric acid on a large scale was developed over a hundred years ago. It turns out that molds can be used to make citric acid from fermented sugars. 

The process is to first make a carbohydrate solution from cheap crops and waste products such as molasses and byproducts of milling corn and then to feed this sugary soup to a strain of mold called Aspergillus niger (please note that this is not toxic black mold but it is in indeed, mold). The resulting solution is mixed with calcium hydroxide to precipitate (make solid) calcium citrate salt out of the solution, which brings us to the point we'd be at if we had started with citrus fruit, rather than sugar soup. The calcium citrate salt is treated with an acid to make the familiar white citric acid powder.

So that's all...pretty gross, honestly. But I am not someone who tosses out something useful just because it has unpleasant beginnings. Mold is used in many edible circumstances when the purpose is to actually eat the mold for improved flavor! There are wines that start with moldy grapes, moldy cheeses, salami with a mold coating, even a type of mold that grows on corn, called corn smut.

 

 
That's some pretty tasty looking mold, if you ask me.

However, there is a small subset of the population that has a severe enough mold allergy, that they may have a reaction to products containing citric acid because of trace mold residues from the manufacturing process. If you have a mold allergy, you'll probably already know it because these other uses of mold will cause you issues as well. It's very unlikely that the microscopic amounts possibly left behind in citric acid would be your first significant exposure to mold. 

There is, however, not really any hard science on citric acid related mold reations, mostly because the number of people affected seems to be very small. There's enough anecdotal evidence though to make me proceed with caution before putting citric acid into all my soap products willy nilly. Where you will find citric acid already is in my solid dish soap, since that soap is possible to use without much skin contact (dish gloves will also keep this much stronger version of our soap from drying out your hands) and the added citric acid really boosts this soap performance as far as leaving less residue in the sink and rinsing cleanly off glassware.

Thoughts?

So what do you think? Is it worth adding citric acid to more of my soaps for the benefit of more lather? Or is it better to play it safe for the benefit of those with possible allergic reactions? 

https://www.usgs.gov/faqs/do-you-have-information-about-water-hardness-united-states

https://www.usgs.gov/media/images/map-water-hardness-united-states

https://en.wikipedia.org/wiki/Citric_acid

https://www.healthline.com/nutrition/citric-acid

https://www.smithsonianmag.com/arts-culture/delicious-molds-four-fungi-fit-for-your-plate-1525717/