Just where and when humans first observed the chemical reaction between oil and potash is unknown. Legend says it may have occurred in ancient Rome, on Sapo Hill, in an unusual scenario where a creek flowed over a deposit of wood ash and animal fats, created through many years of sacrificial fires and beasts incinerated for the gods. This mixture of oil, ash and water, so goes the tale, had its effect on the local populace, for whom cleanliness came noticeably easily when bathing in the current downstream of the sacrifice site. Other centers of soap origin may have existed – but regardless of who first saw the chemical reaction in action and of how the knowledge spread through the world, we can safely assume this: By observation of nature, people learned to recreate the chemistry of water, potash and oil, thereby producing the first liquid soaps.

Subsequently, standards of cleanliness grew and spurred the rise of industries. Solid soaps were innovated in the 19th century, facilitating shipping and selling. And whereas soaps had once been pure and natural blends, the soap industries of the 19th and 20th centuries introduced problematic chemicals to the equation, like propyl alcohol, limonene, benzaldehyde, methylene chloride and many more. Today, some soap ingredients are derived from animals rendered in factories, while others are byproducts of petroleum. Many are toxic, and some are carcinogenic. (Notice how large commercial soap brands tend to list their product ingredients on the back of the package.)

All-natural, plant-oil-based soaps provide a minimalistic alternative to additive-heavy cleaners from larger manufacturers – but one downside remains: the disposable, one-time-use plastic bottles and packaging. Speaking of the packaging, pick up one of these bottles the next time you visit your local natural foods store and read the list of ingredients (which is likely displayed candidly on the front). It probably mentions water, saponified oils and little, if anything, else.

In fact, making soap at home is easy and not much more complex than making bread and certainly simpler than brewing beer. In its most basic form, soap consists of just three components – a strong base (usually potash or, alternatively, lye, which we’ll be using), oil and water. Blended at the right proportions and temperatures, these ingredients produce a chemical change called saponification which renders the lye, normally caustic and dangerous when mixed with water, entirely benign while breaking the oils apart and eliminating their cloying greasiness. And although a curing stage lasts nearly a month while the soap dries and hardens, the first step – and the most logistically, physically and mentally demanding – can take just 30 minutes for practiced home soap-makers.

Now consider that a year’s supply can be made in a batch, and that each bar will cost just over a dollar, and that the soap contains no lingering poisons – and one by one they mount: the good and healthy reasons to free oneself from chemical industries and never buy soap or shampoo again.

Project Steps

Notes before starting:

Do not use any aluminum kitchenware while making soap.

Olive oil need not be extra virgin. In fact, the quality of the oil is almost irrelevant since you’re going to be mixing the oil into a chemical bath of lye and water, and any perceived health benefits of “the good stuff” would likely be figments of your mind. Use the cheap stuff.

Coconut oil can be found at natural foods stores, often in plastic jars but sometimes, and preferably, in bulk. Buy organic or fair-trade of possible.

Potash – potassium hydroxide – is relatively tough to find. It can be made by hand, but that is a how-to tale for another time. The chemistry of potash, too, is more conducive to making liquid soaps. For these reasons and to simplify logistics and to get straight to business, we recommend using lye, as most home soap-makers do. Lye, or sodium hydroxide, is the grainy powder often sold as “drain cleaner.” Yes, we know: Yuck – and if you have potash at hand, great. If not, visit your local hardware store and buy a plastic jar of drain cleaner. You want pure 100% lye.

Step 1

Set up your soap-making station in the kitchen, and begin by weighing out your ingredients and placing each in its own vessel. The water can go into the 40-oz heat-resistant jar. The coconut oil can straight into a clean saucepan.

Step 2

Gently heat the coconut oil on the stove. The chunks of fragrant fat will melt into clear grease.

Step 3

Now don your protective gloves and glasses and SLOWLY pour the lye into the 40-oz heat-resistant glass jar of cold water. Stir with steel spoon. A fast reaction will occur as the temperature shoots to nearly boiling and the mixture momentarily emits a plume of toxic fumes. (You might keep a door or window open at this stage, and do not inhale over the jar.) Insert a thermometer and watch the temperature. It will slowly drop. Your target reading is 80 degrees Fahrenheit.

Step 4

Insert the other thermometer into the pan of melting coconut oil. When it reads almost 90 degrees Fahrenheit and the oil is entirely liquefied, turn off the heat and add the olive oil. The temperature of the blended oils should read 80 degrees.

Step 5

When both the lye water and the oils measure 80 degrees Fahrenheit, combine the two in the 40-oz jar. The mixture will abruptly turn cloudy.

Step 6

Blend the liquid using either an electric egg-beater or stick blender (friends of ours at the Ecology Center of San Francisco have used a home-made bike-powered blender in soap-making). You can also whisk by hand, though this will extend the quarter-hour process to one more than an hour long.

However you approach the blending, your goal is saponification, which occurs plainly and visibly as the liquid turns opaque and thickens. Watch closely, and to test for readiness lift the blender or hand-whisker from the liquid and drizzle the soap across the surface. When it’s thick enough that the droplets remain seated on the surface for a moment before sinking away – this is called “tracing” – the blending is finished.

Step 7 (optional)

If you’re going to add any fragrances, essential oils or oats, now is the time. Add and thoroughly mix – and do it fast, because the soap may be thickening more quickly than you realize. NOTE: Any ingredients added at this stage must be pure, all-natural materials. Artificially scented perfumes, for example, could foul up the saponification process.

Step 8

Pour the soap into your mold. Wooden molds should be lined with parchment paper, milk carton molds thoroughly cleaned.

Step 9

Cover the filled mold with a cutting board or coffee table book and set it aside for one to three days as it hardens.

Step 10

Lift the long soap block from the mold, peel away the parchment paper, and cut the brick into roughly 10 bars. Stand each bar on its end to allow the most surface-to-air contact possible and set them aside undisturbed to cure. Three weeks should do it, at which point the lye’s causticity has fully neutralized and your soap is ready to use.

Want liquid soap?

Easy: Just grind up a bar or two of your solid soap or in a food processor or by hand with a knife, and in a bowl combine the crumbs or shavings with warm water. The soap will dissolve into a soupy liquid. Dilute as necessary, funnel into a squirt-bottle, and – bingo – you have shampoo and dish soap.

Want homemade toothpaste?

You’d might as well make some since you’re learning to make from scratch all the hand, hair and body soaps found in the average household bathroom. It’s simple: Mix 4 parts baking soda, 1 part coarse-grained sea salt, and 1 part vegetable glycerin in a clean salad bowl. Stir. If too sticky, add more glycerin as needed. When you’ve hit the right consistency, add several drops of peppermint or other appropriate oil for flavor. (Ground cinnamon is another option.) The toothpaste is ready. Keep in a sealed jar.

NOTE: Unlike soap-making, mixing toothpaste involves no delicate chemical reactions. Thus, proportions and ingredients can be toyed with as you please.


Congratulations. You can now wash your hands of the chemicals and toxins of the commercial soap-making industries.

Learn more about soap-making here: http://www.eco-sf.org/resources/fact-she...