MAKING SOAP IN SHELBY COUNTY
I teach the four general categories of organic compounds in my Junior College class. “Organic” originally meant that such a compound was produced by life forms. Not always the case, but a good enough definition for this essay. The four categories are carbohydrates (simple sugars, starch, cellulose), proteins (amino acids, enzymes, muscle, hair), lipids (fatty acids, fat, oil), and nucleic acid (genetic material such as DNA and RNA). Of the four, lipids are the richest in energy stored in carbon-to-carbon bonds. Much more energy than that contained in sugar. Lipids are life’s living storehouses, a larder secreted away against times of poor harvest, hunger, and weather. Just look at your nutritional label!
In animal lipids, chains of carbon, bounded by hydrogen atoms, are semi-solid at room temperature. They are called fat, lard, tallow, or butter. Plant lipids are generally liquids at room temperature and are called oils. The number of double carbon-to-carbon bonds account for this fluidity. The level of “saturation” refers to the presence of these double bonds. The nutritional label will indicate if there are fatty acids with no double bonds (saturated, as in lard), one double bond (monounsaturated, as in olive oil), or many double bonds (polyunsaturated, as in lighter oils). Some plant oils with more saturated fatty acids, such as palm or coconut oil, are solid at room temperature. They have many uses in our food and cosmetic industry. Face makeup removal and skin conditioning, for example.
One more scientific description before we continue. The “fatty acid” is the basic unit of a lipid and, as you will see, of soap, too. As a long chain of carbons encased in hydrogen atoms (hydrocarbon), it has a neutral “tail,” meaning that there is no electric charge on that end of the hydrocarbon chain.
Its “head,” however, is composed of one carbon atom attached to a double-bonded oxygen, with that same carbon also attached to another oxygen carrying a single hydrogen. This latter oxygen, with its single hydrogen rider, is called an “alcohol group.” A similar oxygen- hydrogen group gives drinking alcohol its effect. The complete configuration around that one special carbon is called a “carboxyl group.” In water, the hydrogen attached to the alcohol group is drawn away. This leaves the “head” of the fatty acid with a negative charge. A crucial event if you are going to have a successful shower this morning! So let’s lather up.
Here’s the rub. You must first find a source of fatty acids to use as soap. You see, that carboxyl group can also act like a clamp at the end of a train car. Back it up to a locomotive, in this case glycerol-a simple molecule with three free alcohol groups waving in the water-and it will lock onto the fatty acid! Do it three times and the single glycerol engine will pull a train with three fatty acids attached. When you go to the doctor, doesn’t she test for triglycerides? Yup. Each one a glycerol locomotive chugging along in your bloodstream pulling three fatty acids along. The type of fatty acids can make a medical difference.
In fact, most plant and animal lipids are fatty acids carried along in the form of triglycerides. Charge wise, that renders them as neutral molecules. Water is a polar molecule with both positive and negative charged ends. That is why water seems so silky and slick.
Fatty acids carried by triglycerides can’t be pulled apart by water’s ionic attraction. So, to mix oil and water for your salad, you must shake vigorously and pour quickly. Let it sit and the oil separates as a separate layer on top. A good way to smother mosquito larvae in your backyard birdbath!
Remember those famous Roman baths? Steam up, sweat out, and cover your body with pure olive oil. Wait a minute. Olive oil is not soap! The Greeks and Romans did not use soap to wash. They scraped off the spread olive oil that had mixed with the sweaty oils on their skin with a special tool called a “strigil.” Don’t you think that the layer of olive oil left on your body would go rancid? Stink? Yikes!
Well then, when did soap show up? The Roman word “soap” comes from the Celtic culture. It was known to earlier peoples, but generally not used for personal hygiene. Wow, that’s a mouthful, “personal hygiene.” We must be afraid to admit that we are “dirty!”
Back to soap. And a good, clean shower!
It is those fatty acids that work the washing magic. But you have to break them away from their glycerol locomotives. Make them free again! We call this process “saponification.” That is where the lye or potash comes in. Once oil or fat is mixed with lye at the right temperature, it thickens in “trace,” and the fatty acids break off and solidify out as soap salts. Add your perfumes and swirling coloring agents then. Hard soaps and soft soaps vary by which “salt” partner is incorporated in the soap. Generally sodium or potassium. But there are lithium “greases” that are also produced.
Here is how soap works. Your body secretes oils onto your skin with sweat. That is where your unique “bouquet” of body scent comes in. You know, the one your dog recognizes. Actually, that odor is probably produced by metabolic byproducts of the protozoans, bacteria, and fungi that feed on those oils and lounge around on your skin. You carry billions of compadres!
Free fatty acids, when lathered onto your skin as soap, dissolve their neutral tails into your oils and sit on your skin with their charged, carboxyl group heads, bobbing freely around like a colony of sea snakes. Rinse that skin with water and something marvelous happens. The polar-charged water molecules of the water are held onto by the hungry heads of the fatty acid sea snakes. Then as you willingly wash away the water, those fatty acid snakes are swimmingly caught up in the movement, pulling away the tiny blobs of oil in which their tails are buried.
Voila! You’re clean!
Here in Shelby County, you can find longtime soap makers at the summer Farmer’s Market at the Fairgrounds. One local artisan makes soap the “old fashioned way,” with wood ashes at the Painted Stone Settlers pioneer reenactments. And there is plenty of lovely, locally grown, lavender-scented soap sold by the Little Mount Lavender Company store in downtown Shelbyville.
My favorite? It is the soap made by hand by Dr. Maia Langley with my Junior College class in Human Ecology!
Better showers through science!