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CHAPTER 1
Getting Started
Water. Ammonium laureth sulfate. Glycol distearate. Cocamide MEA. Stearyl alcohol. Disodium EDTA. All very common liquid soap ingredients, but the only recognizable ingredient for most consumers is the water.
These laboratory-produced compounds are part of a long list of ingredients found in modern liquid soaps, which are actually detergents. Aside from their cleansing properties, these "soaps" have been engineered for stability because they're often shipped thousands of miles to market and suffer from exposure to heat, cold, and light. Before the days of international commerce and mass marketing, liquid soap was soap, often consisting of little else besides coconut oil and potassium hydroxide.
The ingredients and additives for "old-fashioned" liquid soap are listed in this chapter. You can formulate soap with a single oil and potassium hydroxide, or create blends of many oils enhanced with a wide variety of additives. A review of the procedures and recipes in the following chapters will help you decide before you spend your money.
HARD FATS
Hard fats are composed primarily of stearic, palmitic, and lauric acids. These fatty acids are solid at room temperature, and the fats containing a predominance of these acids — whether tallow, coconut oil, or palm oil — also tend to be hard at room temperature.
COCONUT OIL
Coconut oil forms the backbone of most liquid soap formulations. Why? Because of lauric acid, the predominant fatty acid in coconut oil. Lauric acid possesses one supreme virtue: solubility.
The more soluble the fatty acid, the less potential for cloudiness in the finished soap. Solubility also means that the soap has a quick, voluminous lather. This property is particularly important for liquid soaps because dilution by water reduces the soap's foaming action. The minerals contained in hard water also reduce lather, making coconut oil soaps the best performers in unsoftened water.
Because coconut oil — based liquid soaps are so soluble, higher proportions of soap to water are possible before the soap begins to congeal. A 100 percent coconut oil soap is still fluid at 40 percent soap to 60 percent water, whereas an olive oil soap begins to congeal at a much lower concentration: around 20 percent soap to 80 percent water. This is one reason why most public soap dispensers are filled with coconut-based liquid soap: This won't clog the dispenser.
One drawback of coconut oil is the drying effect of lauric acid. This negative property can be overcome by blending coconut oil with soft oils, such as olive, canola, or safflower oil. Palm kernel oil can be substituted for coconut oil because it has a similar fatty acid profile, but it requires approximately 20 percent less caustic than coconut oil for neutralization. See the chart on page 50 for specific information on the proportions of alkali to oils.
PALM OIL AND TALLOW
Palm oil and tallow possess characteristics that make them ideal bases for opaque hand soaps. They form rich, stable lathers and create a hard, long-lasting bar. These qualities are derived from the palmitic and stearic acids that constitute the bulk of both oils. But palmitic and stearic acids are mostly unwelcome in liquid soaps, where crystal clarity is desired. The two acids react with potassium hydroxide to form insoluble soaps, and these insolubles cloud an otherwise clear liquid. Used sparingly, however, palm oil or tallow gives extra "body" to liquid soap.
In gels, a small percentage of either palm oil or tallow helps prevent "thinning" of the gel during hot summer months.
COCOA BUTTER
Extracted from the roasted seeds of the cacao plant, cocoa butter is an excellent emollient and skin softener. Like palm oil and tallow, however, cocoa butter contains a high percentage of palmitic and stearic acids and should be used judiciously in liquid soap formulations.
SOFT OILS
Soft oils are generally liquid at room temperature: olive, canola, soybean, safflower, corn, or peanut oil. High in oleic, linoleic, and linolenic fatty acids, these oils form moisturizing soaps with thin, weak lathers. A mixture of 10 to 20 percent coconut oil and 80 to 90 percent soft oil forms a soap with enhanced foaming.
For liquid soap formulation, the choice of soft oils is up to the soapmaker because all soft oils (except castor oil) require a similar amount of alkali for neutralization. Aside from affordability and accessibility, these choices are in part aesthetic: How deeply colored is the oil? How strong is its odor? Dark oils, such as soybean oil, impart a markedly amber tone to liquid soap; strongly scented oils, such as sesame oil, can alter the fragrance of the finished soap.
Another consideration in the choice of oils is stability, or shelf life. Soft oils are unsaturated and therefore combine more readily with oxygen than saturated fats, such as coconut oil or tallow. Oxidation leads to rancidity. In general, oils high in linolenic acid are the least stable and most prone to rancidity (see the chart below). But this is a bit simplistic because many other factors influence the stability of a given oil, such as processing conditions, type of container, temperature of storage, and presence of natural antioxidants. It is safe to say that if you start with recently purchased oils that smell "clean" when opened, your finished soap should enjoy a long shelf life.
Other High-Oleic Soft Oils
Canola, almond, corn, and peanut oils, like olive oil, are high-oleic soft oils. Avocado oil contains a high percentage of oleic acid but should be used sparingly because it also contains a fairly high percentage of substances that do not saponify and can cloud liquid soap.
Avoid formulating with vegetable shortening. Through the process of hydrogenation, unsaturated fatty acids are converted into their saturated analogs; for example, unsaturated oleic acid becomes saturated stearic acid. Saturated acids form insoluble soaps, which consequently produce milky liquids.
OLIVE OIL
Olive oil, which is 85 percent oleic acid, has been the favorite of soapmakers for centuries. It penetrates the skin better than almost any other vegetable oil except castor oil. The resulting soaps are moisturizing as well as mild, making olive oil an excellent base for baby shampoo.
CASTOR OIL
Castor oil is in a class of its own. It's part oil and part alcohol a peculiarity derived from the molecular structure of ricinoleic acid, the fatty acid accounting for almost 90 percent of castor oil's bulk. Alcohols act as solvents, and castor oil's solvency is readily apparent in soapmaking; it speeds saponification and adds exceptional clarity to both transparent and liquid soaps. This explains why castor oil is the only soft oil you'll ever see in transparent bar formulations. Aside from its transparency-producing virtues, castor oil is exceptionally mild and is easily absorbed by the skin, making it an excellent emollient and moisturizer.
SULFONATED CASTOR OIL
Also known as "turkey red oil," sulfonated castor oil is created by the reaction between castor oil and sulfuric acid. This oil first proved useful to the textile industry over a century ago; its water- soluble nature not only allowed for better penetration of dyes into wool and other fabrics but also increased the brightness and luster of the colors. "Turkey red" refers to the brilliant red color produced specifically on cotton cloth.
Water solubility makes sulfonated castor oil an ideal superfatting agent in liquid soapmaking, adding the lubricity of an oil without compromising the clarity of the soap. Sulfonated castor oil forms the base of "soapless" shampoos (see recipe in chapter 4) and is effective in both hard and soft water. As an unsaponifiable oil, it should never be substituted for regular castor oil in soap formulations.
WAXES
Waxes are chemically similar to oils except that the wax molecules are composed of more alcohol than glycerol. Small additions of a wax to liquid soaps enhance the moisturizing properties of the lather.
LANOLIN
Lanolin, produced from the oil glands of sheep, is a water- absorbent base material and consequently an effective moisturizer. Because lanolin contains a high percentage of substances that do not saponify, it clouds liquid soap and should be limited to 1 to 2 percent of any formulation.
JOJOBA
Jojoba, which is similar to the sebum produced by our own oil glands, is a liquid wax derived from the seeds of a desert shrub. Mexicans and Native Americans have long used the oil as a hair conditioner and skin moisturizer; modern marketers promote its usefulness as a sunscreen and treatment for wrinkles, crow's feet, and dry skin. Like lanolin, it contains substances that do not saponify, and it must be used sparingly if crystal-clear soaps are desired.
POTASSIUM HYDROXIDE
(CAUSTIC POTASH)
Because of its solubility, potassium hydroxide forms the ideal base for all liquid soaps. Manufactured commercially from the electrolysis of potassium chloride, potassium hydroxide is sold as a liquid or crystalline flake. It's much more chemically reactive than sodium hydroxide, and more potassium than sodium hydroxide is needed to saponify a given amount of fat — 1.4 times more, to be precise.
SOLVENTS
The solvents alcohol, glycerin, and sugar are what enable a soapmaker to transform opaque bar soap into transparent soap. The solvents literally dissolve the soap crystals and then hold them in suspension, allowing the light to pass through.
Solvents are very useful in liquid soap-making. The soap can be dissolved and "cooked" in alcohol (see the Alcohol/Lye Method), and small additions of alcohol, glycerin, and sugar will improve the brightness and clarity of the finished liquid.
ALCOHOL
Alcohols are solvents. In liquid soapmaking, solvents can speed saponification as well as lower a liquid's cloud point, or the point at which insoluble substances precipitate out of solution. When liquid soaps are slightly cloudy because of excess fatty acids or minerals, a small addition of alcohol often clarifies the solution. Excess alcohol, however, reduces the sudsing action of the soap.
The liquid soapmaker has a choice of two types of alcohol: ethanol or isopropyl alcohol.
Ethanol. Colorless and odorless, ethanol is produced from the fermentation of sugar, starch, and other carbohydrates. In liquor stores, ethanol is sold under the brand names Everclear and Clear Springs. Scientific supply houses sell denatured ethanol in gallon containers a much cheaper option than pure liquor store ethanol. When ordering denatured alcohol, be sure to specify SDA (specially denatured alcohol) 3A or SDA3C, two cosmetic grades approved by the FDA. Both have been denatured with trace amounts of isopropyl alcohol and methanol.
Isopropyl alcohol. Common isopropyl alcohol, or rubbing alcohol, can also be used for liquid soapmaking. As a solvent, it's "weaker" than ethanol, but because potassium soaps are so soluble, this weakness isn't a handicap. The strong odor of isopropyl alcohol can potentially taint the finished liquid, but this problem is easily rectified by evaporating the alcohol out of solution at the end of the soapmaking process.
All drugstores carry isopropyl alcohol, usually at a 70 percent strength (the remaining 30 percent is water). For the purposes of liquid soapmaking, stronger concentrations, in the range of 90 to 99 percent, are desirable. Many pharmacies stock the stronger solutions on the shelf, and some will special-order 99 percent concentrations; otherwise, contact the nearest scientific supply house.
GLYCERIN
A natural by-product of saponification, glycerin is technically an alcohol. Added to finished liquid soap, it lowers the cloud point the same way alcohol does, helping clarify residual milkiness. In addition, it functions as a humectant, drawing moisture from the air and holding it to the skin. Like ethanol or isopropyl alcohol, excessive amounts of glycerin dampen the foaming action of soap, though small amounts actually boost the foam. Purchase glycerin at pharmacies or through the suppliers listed in Resources.
OTHER KEY INGREDIENTS
In the strictest sense, soap consists of a hydroxide in chemical combination with a fat. But many other ingredients determine the appearance and quality of the finished soap — what kind of water is used for both the lye solution and the dilution of the soap base, how the soap is thickened and preserved, and what to use for creating a neutral pH. The following are descriptions of some of these ingredients.
SUGAR
Small percentages of sugar solution added to liquid soaps help dissipate cloudiness. Ounce for ounce, sugar is a more effective clarifier than glycerin, though it lacks glycerin's moisturizing properties.
SOFT OR DISTILLED WATER
Minerals in hard water react with fatty acids to form insoluble fatty acid salts. The result? Cloudiness, much like the cloudiness formed by insoluble palmitic and stearic acid soaps mentioned earlier. For this reason, the use of soft or distilled water is essential for all phases of liquid soap production.
ROSIN
Pears, the very first transparent soap, was formulated with rosin. Distilled from the oleoresin of pine trees, rosin saponifies much like an oil, but without any resulting glycerin. It imparts clarity to soap and a smooth cold-cream finish to the lather. It also acts as a detergent and preservative. Sold as fragrant, amber-colored crystals, rosin can be purchased through the suppliers listed in Resources.
BORAX, OR SODIUM BORATE
The detergent and water-softening properties of borax were first discovered by Native Americans, who noticed that clothing washed in streams near borax deposits came out cleaner.
Borax is one of the best all-around additives for liquid soaps, possessing many desirable qualities. It's a viscosity modifier (thickener), an emulsifier, a water softener, a moisturizer, a foam booster and stabilizer, a pH buffer, and a preservative. Pharmacies carry borax (often behind the counter, so ask if it's not on the shelf), or it can be obtained from the suppliers listed in Resources.
CALGON
Like borax, Calgon brand bath preparation enhances foaming, softens hard water, and triggers gelling in liquid soaps. Calgon is a blend of various sodium salts, mainly sodium carbonate and sodium hexametaphosphate. Buy the nonfoaming bath variety. One drawback of Calgon is that the finished soap turns blue because of the dye in the powder.
NEUTRALIZERS
The recipes in this book all contain slight excesses of potassium hydroxide. This ensures that no unneutralized fatty acids remain at the end of saponification. The excess alkali can be neutralized with an acid. Boric acid, the buffer of choice used by old-time liquid soapmakers, can be found in any pharmacy. Citric acid also works. Wine-making supply shops carry citric acid, or it can be purchased through the suppliers listed in Resources.
Borax, at a pH of 9.2, is also an excellent neutralizer. If you use borax as a thickener in any formulation, no additional neutralizers will be necessary.
POTASSIUM CARBONATE
Potassium soap bases are quite sticky and viscous; stirring them is almost as difficult as stirring hot tar. One additive used by old-time liquid soapmakers to loosen the soap was potassium carbonate, or pearl ash. Pearl ash is a salt of potassium. When it is added to a potassium paste, the molecules of the carbonate actually insert themselves between the molecules of potassium hydroxide, making the soap much more pliable. Potassium carbonate is an optional ingredient, but if you'd like to experiment with it, purchase it through any scientific supply house.
PRESERVATIVES
The most effective preservative for liquid soap is complete saponification. Oxygenated fats trigger rancidity. Because oxygen attaches most readily to free fatty acids, it follows that thoroughly neutralized soap offers no oxidation sites. Fresh, clean-smelling soft oils are also very important because soft oils are by their very nature unsaturated and are more receptive to oxygen than saturated fats such as coconut oil and palm oil. A completely saponified rancid oil will produce a rancid-smelling soap. No amount of cooking reverses preexisting rancidity.
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Excerpted from "Making Natural Liquid Soaps"
by .
Copyright © 2000 Catherine Failor.
Excerpted by permission of Storey Publishing.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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