Additives which harden soaps

It’s surprising that rendered animal fats, ashes and water could help produce cleanliness. But mix them together and soap is created.

Photo Credit: Samantha Grandy
By Regenia Butcher

If cleanliness is next to godliness, perhaps society should think more highly of the soapmakers.

One of the most basic explanations of soap is that it is a product that results when a fat mixes with a powerful alkali. Plant oils have forever been used for their cleansing properties. However, the first “real” soaps were made of animal fats or plant oils mixed with ashes (the alkali). Early soap was soft and was stored in clay containers, kegs or barrels. Although ingredients and techniques have changed throughout the years, the basic formula for making soap (fat and water and alkali) has remained the same.

To understand what causes soap to harden, we must know a bit about how it is made. Early soapmaking required the soapmaker to build a fire, collect its ashes and drain water over those ashes until “lye” was produced. Animal fat was boiled in water and then cooled, which separated the impurities and allowed the “rendered” fat to be collected from the top. The fat and lye were finally mixed together, which caused a reaction known as “saponification.” The saponification continued as the soap “set” and evaporated its moisture. This mixing and evaporation process also changed the lye and made it non-toxic.

Today, anyone wanting to make a batch of soap can simply purchase the lye and other ingredients, combine them, pour the mixture into molds and let it “set” or “cure”. The lye of choice is the “Red Devil” brand. If they want to simplify the task even further, they can purchase a “melt and pour,” which is a solid “base” soap to which fragrances, colorings and embellishments can be added and then placed in molds to harden. This method is a short cut that eliminates the concerns of having to determine the correct ratio of the lye and fat and then having to mix them together.

Whether you use the “melt and pour” method or make soap from scratch, the main thing to use is good water. Distilled water is highly recommended because the additives in regular home drinking water could interfere with the soapmaking process.

Fats, oils and waxes are used to harden soaps. Beef or sheep tallow and pork lard have been used for years as the main fat ingredient for bar soaps. Tallow is the fat that has been rendered. Vegetable shortening and cocoa butter are used as well. Palm oil is also often preferred because it helps the batch to process quickly and to preserve well. Coconut oil and olive oil are also choices to harden soaps. Stearic acid is popular for hardening soaps and is found in tallow and palm oil or purchased separately. Another item that has been welcomed for its hardening quality is beeswax. Candelila wax and Bayberry wax can be used instead of beeswax, as can JoJoba oil since it has a wax structure which causes a batch of soap to thicken more rapidly.

Every fat and oil that is chosen is affected by the lye differently, so the fat/lye ratio needs to be adjusted accordingly. When making soap from scratch, each fat or oil chosen must make the lye react or soap will not be produced. Later in the process, additional oils can be added for other reasons such as fragrance, moisturizing or lather enhancing.

Hand-milled soaps are those that have extra, previously-made, shaved or diced bits of soap added into their mixtures. This is done after a batch has been saponifying for a few days. At that time, this “curing” soap is remelted and the previously-made, solid soap is grated into it. Also, at that time, other additives can be blended in. Most commercial soaps are milled.

The ingredients and techniques mentioned have been widely accepted when it comes to producing hardened bars of soap.

The next time you make a conversation faux pas and someone suggests that you wash your mouth out with soap, ask, “Short cut or made from scratch? Saponified or still curing?” Afterall, there is a difference.