Modern Soap is Detergent
Even though we call it soap, almost all the product we use today for cleaning our skin isn't traditional soap. It's detergent.
That's not to say that detergents aren't good cleaners. In fact, they are fantastic. They are very good at what they do - stripping all the dirt off our skin.
The problem is that they are TOO GOOD at what they do. They not only strip all the dirt, but also all the good things that are part of our skin. Like skin oils.
They are also full of interesting chemicals. When we use these detergents on our skin, our bodies absorb some of the chemicals as well. The government has already warned us about using these chemicals, and is even doing what it can to teach us to wash our hands properly.
Here are more details about the chemicals used in modern "soaps" including shampoos, conditioners, and lots of other personal care products.
In modern liquid soaps, the ingredient list extends far beyond fats and bases. Below is a list of the seven most common ingredients in liquid soap, along with their functions.
- Sodium Benzoate and Benzoic Acid
- Water-based soap will need a preservative — if not, the product can become rancid and develop mold and bacteria. Even cold-process soaps made without water will need preservatives if they will contact water, which is true of most cleaning products.
- Sodium benzoate is the sodium salt of benzoic acid, used as an anti-corrosive and preserving agent in a wide range of industries. It goes by a variety of names, including benzoate of soda, sobenate, natrium benzoicum, and benzoic acid.
- In cleaning, sodium benzoate is beneficial for its antifungal and intrinsic preserving qualities. As a preservative, sodium benzoate extends the shelf life of liquid soap and prevents fungi like yeast and mold from colonizing. Sodium benzoate is often an alternative to parabens in cleaning products such as dishwashing detergent, toilet bowl cleaners, and upholstery cleaners.
- Sodium Laureth Sulfate
- Sodium laureth sulfate (SLS) is both a surfactant and emulsifier and contributes a sudsing and foaming element in soap.
- Also known as sodium dodecyl sulfate, SLS is highly effective at removing oils and residues. Since it can clean grease from engines and floors, industrial settings often use liquid SLS soaps in high amounts.
- For personal care soaps and household products, SLS is more common in less concentrated amounts. In addition to emulsifying oils, SLS suspends dirt and soil in water, allowing it to wash away easily. It reduces the surface tension of water, allowing it to more thoroughly wet and clean surfaces.
- Methylisothiazolinone and Methylchloroisothiazolinone
- Methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT) are common preservatives in many liquid soaps. Both chemicals individually work to inhibit bacteria growth, but they are most often combined.
- Typically, MIT and CMIT are ingredients in cleaning and personal care products, and also act as preservatives. Powerful biocides, they eradicate the slime-forming fungi, algae, and bacteria that can develop in many industrial settings, including fuel storage tanks, water cooling systems, paper, and pulp mill water systems and oil extraction systems.
- In soap, MIT and CMIT are often excellent for cleaning wood products, as they can control sap stain, mold, and mildew.
- Cocamidopropyl Betaine
- Cocamidopropyl betaine (CAPB) is a surfactant — it helps water clean effectively.
- CAPB derives from chemicals found in coconut oil and is the result of mixing raw coconut oil with the chemical dimethylaminopropylamine. Classified as an amphoteric surfactant detergent, CAPB can function as either an acid or a base, depending on its chemical surroundings. With a polar head and a hydrocarbon tail, CAPB helps soap break down debris and wash it away in water.
- CAPB acts as a thickening agent in many liquid soaps. Manufacturers include CAPB in their liquid soap formulas for its surfactant and foaming properties — in soaps, CAPB creates a rich and thick lather. CAPB also has some antiseptic properties, which makes it a common addition in personal sanitary products.
- Many liquid soaps contain some fragrance. The exact ingredients vary from manufacturer to manufacturer — currently, the law doesn't require the fragrance industry to disclose the specific chemicals they use in their scents.
- In one fragrance, there could be hundreds of ingredients or just a few — more than 3,500 oils and chemicals are approved for use in fragrance products. These add a perfuming element to soap, helping it deodorize as well as clean surfaces.
- Synthetically produced fragrance oils are the most popular choices for scented liquid soaps. When compared to other fragrance options like essential oils, synthetic fragrances are inexpensive and relatively easy to produce. That makes them an economical and attractive choice for many companies.
- pH Adjusters
- In chemistry, pH is the measure of the acidity or alkalinity of a solution or surface. The higher the pH number, the more alkaline a substance is — low numbers indicate acidity. A neutral pH is seven — pH numbers lower than seven are acidic, and numbers higher than seven are alkaline.
- The human body has a natural pH of 7.4. By nature, soap is an alkaline substance and will have a high pH balance. However, if a soap will come into contact with humans, it should never have a pH higher than 10 — the closer the soap's pH is to the pH of human skin, the better. If the pH of the soap is too high, it will be irritating and even toxic to humans.
- In liquid soaps, some chemical ingredients alter the pH balance of soap. Most often, the pH adjusters in liquid soaps will be citric acid or sodium chloride.
- Citric acid is a naturally occurring chemical in citrus fruits and results from the fermentation of carbohydrates. An acid, this product lowers the pH of soaps, making them less alkaline. Citric acid enhances the effectiveness of preservative and antioxidant ingredients in soaps.
- Sodium chloride, or salt, reduces the pH of soap solutions. It acts as a stabilizing agent, helping pH levels remain steady. A thickening agent, sodium chloride also has a de-greasing effect, enhancing the cleaning potential of liquid soap.
- In liquid soaps, dyes give the soap an appealing color. Like fragrances, the exact ingredients of synthetic dyes depend on the specific manufacturer. Often, they chemically derive from petroleum and coal tar.
- The purpose of dyes is purely aesthetic — they make the product visually appealing and have little to no functional value. Because of this, many companies choose synthetically produced dyes and colorants, as opposed to naturally derived compounds, since synthetic dyes are almost always cheaper and more readily available.
- The best dyes have long-term color stability and resist fading. Common color choices for liquid soaps are yellow, blue, and green, but the right dye can achieve almost any color.