Fatty Acids and Lye… Oh My!

This past weekend, I had the honor of being the resident Pioneer Soapmaker at an outdoor fall festival. My task was to explain, to a crowd of 6000 people over a span of six hours, how our country’s settlers made and used soap.  What I found, though, was that most visitors were far more interested in modern soapmaking: how we do it today, why soap works, and what it’s made of.  And they wanted to know details! Upon my return home, I thought, now that’s a great blog post.  So, I’d like to offer a big thank you for so many inquisitive minds and great questions!

What is soap?

Soap, at its most basic chemical level, is a salt.  The head of a soap molecule is attracted to dirt, and its tail repels dirt. That’s why it cleans!  And this salt, like any other, is created by the chemical reaction between two ingredients:  An acid and a base.  We all know that lots of fat isn’t good for our insides, but interestingly, as far as our outsides go, many fats and oils are great for our skin and are technically made of acids (ever heard the term “fatty acids”?), and that’s what we use to make soap.  Some are animal products–lard from beef, for example–and some are derived from the plant kingdom, such as olive oil or  coconut oil.   In soapmaking, we choose from two bases, also called alkalis:  Sodium hydroxide, or lye, combines with fats/oils to create solid bar soap.  Potassium hydroxide combines with fats/oils to create liquid soap.

Soapmakers carefully craft their soap formulations, aiming for balance among specific factors in the finished soap. Every fat or oil contains a unique combination of fatty acids, each with specific properties, and soapmakers skillfully combine multiple fats/oils within one formula to reach just the right balance of mildness, great lather, feel on the skin, and hardness for a long-lasting soap.  Coconut oil contributes to hardness and great lather, but too much of it and you have a soap that will feel drying to your skin.  A pure olive oil soap creates a lather that some people don’t care for (many people prefer a more fluffy lather), but it creates a wonderfully mild soap.  Combine the two, and you are on your way to a better formula.  As you can see from this simple example, balance is key!

Now, let’s revisit the concept of alkalis. You might be a little put off by the prospect of rubbing lye on your skin… so, a little more information.  First of all, you literally cannot make bar soap without lye.  I guarantee you that every single bar of  true soap you’ve ever used was made with lye.  Secondly, the interaction of lye and fats/oils is a chemical reaction, a complete transformation.  These substances chemically combine to create a completely new substance, and that substance is soap, which contains some really good stuff… read on!

We’ve all heard the stories of soap from even the early 20^th century being harsh and drying.  Modern handcrafted bar soap isn’t your grandma’s lye soap!  Nowadays, we understand so much more about the chemistry of soapmaking, and we know exactly how much alkali we need to combine with our fatty acids to create a wonderful, mild soap.   Many soapmakers, myself included, even use computer software to help us create our formulas.  Soapmaking is the ultimate meeting point of art and science!

The good stuff

Handcrafted soap aficionados cling tightly to their bars and refuse to switch back to detergent-based “cleansing bars”!  One benefit they claim is that handmade soap is more moisturizing.  Let’s clarify that statement a little.  Glycerin is present in artisanal soap as a naturally-occurring byproduct of the chemical transformation of alkalis and fats.  Glycerin is good stuff! It’s a humectant, which simply means that it draws moisture from the air into your skin.  All skin types need moisture, even oily skin! Many creams and lotions, what we think of as moisturizers, rely on direct skin application of oils (yep, fatty acids) to help your skin feel soft. Glycerin is not an oil and is non-comedogenic (meaning it will not clog your pores).  So, handmade soap works a bit differently than moisturizers, and I like to make sure my customers know the difference.

Mass-manufactured, commercial soaps are often stripped of their glycerin through additional manufacturing processes. Glycerin is very profitable (more profitable than soap itself, actually) and is used to make other products. Handcrafted bar soaps, on the other hand, retain all of their naturally-occurring glycerin, and many people notice a difference in how their skin feels with regular use.

The benefits of handcrafted soap don’t stop there.  With some very notable exceptions, detergents are largely petroleum-based and are not biodegradable.  Soap, on the other hand, biodegrades and is thus a “greener” product.  And when you purchase from a soapmaker who specializes in creating handcrafted soaps, you get the added benefit of direct interaction and access to more information about the product you are choosing for yourself and your skin.  Many of us choose to make soap with only natural ingredients, such as essential oils and botanicals, or soap that is very beautiful and unique to look at.

OK, but how do you make it?

The soapmaking process itself is very simple!  Most of what happens in the soap pot has been carefully planned and formulated long before soapmaking begins.  I’m going to describe “cold process” soapmaking, so named as it relies on no external heat source to make soap.  There are other methods; this is my favorite.

First, a liquid alkali solution is created by adding lye to water (I use distilled water to prevent any excess minerals from complicating things in the pot).  This is added to the fats and/or oils, and as they are carefully and thoroughly combined, a chemical reaction starts to occur right before your eyes!  What looked like a murky, oily slurry starts to take on a silky, creamy appearance and is about the consistency of thin cake batter.  (It’s easy to fall in love with the process!)

Next, we add scents (essential oils or fragrance oils), pigments, herbs, or other goodies (for example, I add corn meal to my Gardener’s Hand Soap for scrubbing action) to the pot.  Here is where the soapmaker changes from chemist to artist.  Many soapmakers create stunning, colorful swirls and layered effects by coloring different portions of the soap mixture and pouring them into the soap mold in special ways.  Every soapmaker has his or her own special touch and signature.

Whether pigmented or plain, the liquid “raw soap” mixture is poured into a mold.  I use rectangular wooden molds lined with parchment paper (just like lining a baking sheet, for easy removal of my soap).  Other soapmakers use special plastic or silicone molds.   The soap is then covered, insulated with blankets, and left to rest for a day or so.

This resting period, however, is anything but rest!  The chemical transformation continues.  The soap naturally heats up (this is why we insulate it: to protect heat loss) and goes through a few more visible stages of transformation until finally it cools down by itself and has hardened to where it can be removed from the mold.

At this point, the soap is sliced and placed on racks to cure, or harden, for up to a month.  This creates a longer-lasting bar of soap and ensures that the chemical reaction is given more than enough time to complete.

Whew!  Soapmaking is simple but not easy! Did you know soap took so long to make?  And this is why sometimes your favorite variety of soap is out of stock for longer than you’d like:  You can’t rush the soapmaking process, and we were probably just as surprised as you that it sold out so fast!

So, there you have it!  Hopefully I’ve demystified soap and soapmaking a little for you.  Amazingly, the soapmaking process has remained largely unchanged over time, and this is what really stood out for our festival visitors.  I’m proud to be among the many contemporary artisans who bring you this time-tested, beautiful craft, a true blend of art and science.

____________________________

Michelle Gilbert-Hoskin, owner and creative director of Sarva Natural Artisan Soaps, receives wide acclaim for strikingly beautiful soaps which feel and smell as good as they look. Sarva creates artisanal soaps to benefit body, mind, spirit, and planet using principles of aromatherapy, completely natural/vegan-friendly and sustainable ingredients, and 100% postconsumer packaging. Michelle is also an aromatherapist and holistic wellness practitioner in private practice.

---

More about the author:  Guest posts are provided through article submissions. Read more from this author

---

Related posts:

1. Do You Saponify?
2. The Unchanged History of Soap
3. A Closer Look at Sodium Hydroxide