What is the dirt that has to be removed? It consists of: Dust, Soot (from the air), Sweat, Breakdown products of serum, Residues of cosmetics and makeup previously applied to the skin, and Other substances carried in the air which vary depending on the geographical location and immediate environment. All the above substances stick to the thin, oily layer on the skin’s surface. Since the dirt is embedded in the oily layer, washing with water is not effective enough to cleanse the skin. Water is repelled by the oil, and is not able to remove the oily layer of the skin surface containing the dirt particles. Anyone who has ever tried to wash oil or fat off one’s hands will know that water alone cannot remove it. Thus, to effectively remove the dirt embedded in the oily layer on the skin’s surface, one has to use soap.
The active ingredients in soaps consist of salts of various fatty acids.
Fatty Acids Commonly Used in Soaps: Stearic acid, Palmitic acid, Oleic acid, Myristica acid, Lauric acid
In terms of its basic chemical composition, regular, classic soap, known as hard soap or toilet soap, comprises the sodium salts of fatty acids. These fatty acids are derived from either animal or vegetable sources. Because of soap’s particular molecular structure, the soap particles “coat” the fat droplets in which the dirt is embedded, and allow them to be washed off the skin with water. These soap structures, called micelles, coat the fat (and dirt) particles, allowing them to be removed from the skin. The soap molecules arrange themselves in the form of micelles because of the electric charge they carry. The soap micelles surround the fat droplet, and thus enable its removal from the skin.
Normal tap water contains calcium and magnesium. When ordinary soap is used with tap water, calcium and magnesium salts of fatty acids are formed. These are “sticky,” not readily soluble salts. The salts stay on the skin surface and may lead to skin irritation. Another reason regular soap may cause skin irritation is that it has a high pH. The pH of regular soap lies between 9 and 10 (and sometimes higher than 10) higher than the normal skin pH (which is between 4 and 6.5). Consequently, it raises the skin’s pH. However, healthy skin has mechanisms for adjusting its pH, so that shortly after it has been exposed to regular soap, its level of acidity returns to normal. The pH returns to normal any time from half an hour to two hours after soap has been used. Nevertheless, in some people, abrupt changes in pH can cause significant skin irritation. Therefore, the current trend in the cosmetics industry is to adapt the pH of cleansing agents and other cosmetic preparations to that of normal skin.
Skin Acidity Protects Against Infections
The acidity of the skin is a protective mechanism of the body against bacterial and fungal infections. The natural pH of the skin acts as a protective acid mantle.The “pH factor” is a numerical value that expresses the level of acidity or alkalinity of a solution. The acidity of a solution is determined by the concentration of hydrogen ions in it. pH values range from 0 to 14. The real value of the pH of a solution is derived from a logarithmic calculation based on the concentration of hydrogen ions in the solution.
There are four groups of surfactants such as: aniconic surfactants, Cationic surfactants, Nonionic surfactants, Amphoteric surfactants. The nature of each group is determined by its chemical charge. Each surfactants group has different chemical properties that affect the way it cleans.
Clarification of the Term “Detergent”
Some people include any cleaning agent under the definition “detergent.” However, the term “detergent” actually refers to a soap less soap. In general, manufacturers avoid using the term “detergent” with skin cleansing agents or shampoos; they prefer to use the terms “soapless soap” or “surfactants.” This is because the average person tends to associate the word “detergent” with those strong detergents used for cleaning dishes, etc. In fact, all detergents carry out their cleaning action by the same principle. Synthetic soaps usually cause less skin irritation than regular soaps do. The pH of synthetic soaps can be adjusted to that of the normal skin by the addition of substances such as lactic acid or citric acid. Some of the soaps on the market are a combination between regular soaps and synthetic soaps. Hence, they are actually made up of regular soaps, composed of sodium salts of fatty acids, to which surfactants have been added. The resulting pH lies somewhere between the two types of soaps, according to the amount of surfactants added.
Are Surfactants in Soaps and Shampoos Hazardous to Health?
Sodium lauryl sulfate and sodium laureth sulfate are surfactants contained in a range of cosmetic products, mainly liquid soaps and shampoos. Since the 1990s, an increasing number of publications has started to appear in the Internet, warning of the risk of exposure to these substances. Consequently, the Cosmetic Ingredient review Expert Panel, the U.S. cosmetic industry’s independent body of experts for the safety of cosmetic ingredients, has examined this issue. The panel concluded that these substances are safe for use in low concentrations, intended for cleaning skin and hair, and when washed out shortly after being applied. However, similar to the effect of other surfactants, these substances may irritate the skin and eyes of some people. The severity of irritation increases with the amount of surfactants in the preparation. Irritation is fairly common when dealing with concentrations of over 2%.
Substances that alter skin pH are usually acids, such as lactic acid and citric acid. The aim is to adjust the pH of the substance to the normal pH of healthy skin (the normal value being between 4 and 6.5). Certain soaps are designed to deliberately lower the skin pH, since lowering the skin pH is supposed to produce some antibacterial effect.
Certain soaps contain other ingredients, such as vitamins, various medical preparations, and a variety of exotic “natural” ingredients (usually derived from fruits, other plants, etc.). In most cases, these additives are of no documented medical value. Soap is in contact with the skin for a brief period only, and, in any case, if the soap performs as it is supposed to, these substances would quickly be washed off the skin. The effect of any additive on the skin must be considered. If a certain ingredient really does benefit the skin, it would be preferable to use some other cosmetic preparation (such as a cream or an emulsion) containing the required ingredient. That way, by applying the preparation to the skin, the substance in it would be in contact with the skin for a longer period and may truly have some beneficial effect on the skin.
Mild” or “hypoallergenic” soaps have had certain ingredients, such as fragrances and coloring agents, removed. The substances excluded are those that, statistically, have a higher chance of causing skin irritation or allergic reactions. Another feature of these soaps is that they may contain substances from the betaine group, which are amphoteric surfactants. These are known to be relatively mild, and do not tend to cause stinging of the skin or eyes. Nevertheless, even “mild” and hypoallergenic soaps can cause skin irritation and allergic reactions-although the likelihood of this happening is theoretically less than with regular soaps. Hypoallergenic soaps are designed for use by people with delicate skin and for infants.
As noted above, some of the soaps intended for use in acne contain antibacterial substances such as benzoyl peroxide. Benzoyl peroxide is a strong oxidizing agent that penetrates the hair follicle and acts on the bacteria that are involved in the development of acne. The other soaps intended for use in acne are mainly those designed for use on oily skin, which have very potent cleansing properties. Reducing the oiliness of the skin may help in the treatment of acne. Note, however, that most of the medical preparations used today in the treatment of acne may dry out the skin. This, in addition to excessive use of soaps that also tend to dry out the skin, can lead to extremely dry skin.
A mild soap, suited to the skin type, should always be used. For dry skin, soap with moisturizer should also be used. Excessive scrubbing of the face while washing is unnecessary. There is no advantage in using an abrasive substance or device to remove dead cells. They will fall off anyway. When drying the skin, vigorous rubbing, which may irritate the skin, should be avoided. The face can be wiped by gently dabbing with a soft towel.