August 2, 2015

Fatty acids and lye… oh my!

For a decade, I was the Creative Director of an aromatherapy soap company. Soapmaking is an art form largely unchanged over hundreds of years. Read on to learn how soap is made, why handmade soap is great for your skin, and more.

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!  It is created by the chemical reaction between two ingredients: an acid and an alkali.  We all know that lots of fat isn’t good for our insides, but many are great for our skin. Fats are technically made of acids (think “fatty acids”), and that’s what we use to make soap.  Some are animal products–lard from beef, for example–and some come from the plant kingdom, such as olive oil or  coconut oil.  In soapmaking, we choose from two 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 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 and soap  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!

Wait… there’s lye in soap?

You may be a little put off by the prospect of rubbing lye on your skin… so, a little more information.  Firstly, you cannot make bar soap without lye.  Every single bar of  real 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–soap–which contains some really good stuff… read on!

Some people say  soap from even the early to mid 20th century was harsh and drying.  Modern handcrafted bar soap isn’t your grandma’s lye soap!  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 use computer software to help us perfect our formulas.  Soapmaking is the ultimate meeting point of art and science!

Benefits of handmade soap

It’s great for your skin

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, but let’s clarify.  Glycerin is present in artisanal soap as a naturally-occurring byproduct of the chemical transformation.  Glycerin is good stuff! It’s a humectant,  drawing moisture from the air into your skin.  All skin types need moisture, even oily skin! Many creams and lotions 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.

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

It’s environmentally friendly

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.  Many artisanal soaps are made with only natural ingredients, such as essential oils and botanicals, adding to its natural appeal.

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.

First, a liquid alkali solution is created by adding lye to water.  This is added to the fats and/or oils, and as they are carefully and thoroughly combined, a chemical reaction starts to happen 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 (such as essential oils), pigments, or other botanicals to the pot.  Here is where the soapmaker changes from chemist to artist.  Many soapmakers create stunning, colorful swirls by coloring different portions of the soap mixture and pouring them into the soap mold in special ways.  Every soapmaker adds a special touch, like a signature.

Whether pigmented or plain, the liquid “raw soap” mixture is poured into a mold. 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 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?  You can’t rush the soapmaking process!

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 hundreds of years.  I’m proud to be among the many contemporary artisans who enjoy this time-tested, beautiful craft, a true blend of art and science.

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Michelle Gilbert

Michelle Gilbert, CCA, APAIA, R.SPE.P. is an educator and writer who helps aromatherapy entrepreneurs create better products, services, and results. Her work has been featured in Prevention, AromaCulture, and Health. She offers personal mentoring, freelance writing, and formulation review services for professionals and entrepreneurs who want more income and satisfaction from their work with essential oils.

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