The aim of cleansing is to remove:
- surface dirt
- all make-up
- the top layer of dead skin cells
- potentially harmful micro-organisms (bacteria).
The way in which any individual chooses to carry out this process is determined by habit, skin feel requirements and activity.
What goes to make a cleansing product?
For many generations soaps have been made by the extraction of oils and tallows from plants and animals and then treating these with alkalis to neutralise the fatty acids they contain. Soaps are good emulsifiers (that is, they hold solids and oils in liquids in emulsion form so that they can be rinsed away), they have reasonable lathering power and an emollient action. Unfortunately, two problems are associated with soaps.
Firstly, because of their powerful cleansing action, overuse may completely eliminate the protective lipid film on the skin surface, which helps maintain the skin's physiological balance. As a result they may give rise to irritation.
Secondly, some soaps are alkaline (they have a high pH, around 9). Since skin pH is about 5, washing with soap leads to pH increases on the skin that can last for up to two hours.
'Oily' soaps are enriched with emollients such as glycerol, fatty acids or oils, which have a softening and smoothing action. They can leave the skin softer than ordinary soap does by avoiding excessive removal of lipids from the skin surface, but they suffer from the same pH problem.
Most hygiene products contain ingredients called surfactants (or sometimes detergents). The terms include a wide range of substances, all of which are effective to a greater or lesser degree in dispersing greasy materials in water. Scientists call these greasy materials hydrophobic, from the Greek words meaning 'water-hating' because oils will not mix with water unless 'helped' by a surfactant. Soaps are surfactants, strictly speaking, but the term is usually kept specifically for man-made (synthetic) surfactants.
Surfactants are found in laundry detergents, liquid cleansers, shampoos and shower products. Their chemistry makes it possible for them to remove soiling from many different materials, including skin and hair, so that oil and grime can be rinsed away. Some surfactants are harsh to the skin while others are very mild, depending on their type. Based on this wide variety of available surfactants, not all cleansers ar the same. It is important to use products that best fit your skin type.
Surfactants are classified according to their structure:
- cationic surfactants (ammonium compounds): these are poorly tolerated by most people's skins, and are now hardly used at all in skin care products
- anionic surfactants such as sodium lauryl sulphate - their molecules have a negatively charged 'head' and a long hydrophobic 'tail'; these are widely used because of their good lathering and detergent properties
- amphoteric surfactants such as the betaines, and alkylamino acids - these are well tolerated and lather well, and are used in shampoos
- non-ionic surfactants such as sucrose esters - overall these molecules are uncharged; these are tolerated better than other types, but do not lather particularly well.
Syndets (short for 'synthetic detergents') are mixtures of synthetic surfactants, mainly anionic surfactants with some added amphoteric surfactants to improve their tolerability. Their potential lies in the fact that their pH may be adjusted to that of skin, and they can be enriched with oily compounds.
To best maintain the skin surface's physiological balance, it may be better to use syndets rather than soaps for all personal cleansing. This is especially true for young children, whose skin is more delicate than adult skin. It is also true for the sensitive skin of the scalp, for which the best care centres on the use of a mild shampoo formulated for frequent use.
All modem well-formulated facial cleansing products are based on synthetic detergents.
How Often Should We Clean Our Skin?
Some people clean their skin only rarely: others are almost obsessive, and go through an elaborate ritual several times a day. (In just the same way, people vary widely in the frequency with which they wash their hair - anything from once a week to twice daily.)
Regular cleaning should not damage the skin provided that the products used are well formulated and mild to the skin.
These needs of course change with time, as the effects of intrinsic and extrinsic aging become apparent.
Choosing a facial cleanser
Facial cleansing should be effective without irritating the skin, and to achieve this it is important to choose the most appropriate products. The following points must be considered when choosing:
- skin type
- any skin problems present
- skin allergies.
Several forms of facial cleansers have been developed to deal with cleansing different skin types, and to avoid drying the skin as traditional bar soaps tended to do.
Cream, milk or lotion cleansers are particularly suitable for removing make-up and other solid residues from dry skin. All these are emulsions (see Moisturizers): they use the dissolving action of oils to remove make-up and other products left on the skin's surface. At the same time they can be formulated to leave behind a moisturising (emollient) film, which prevents too drastic a removal of fats from the skin.
Facial cleansers should remove oils and other fatty secretions from the sebaceous glands in the skin, but at the same time they should not remove from the stratum corneum the natural lipids like ceramides, which have an important role in preventing an excessive loss of water from the skin.
Facial Cleansers for Dry Skin
In cleansing dry skin the most important aspect is total removal of products. Facial cleansing products may be spread on the skin surface with the fingers or a pad, and then wiped from the skin with a tissue or rinsed off with water. Manufacturer's instructions must be followed carefully.
Products use the solvent effect of ingredients such as mineral oils and syndets to dissolve make-up and dirt present on the skin, and contain moisturising ingredients as well.
Facial cleansers for oily skin
Oily (greasy) skin is particularly common in young people, and may be accompanied by an acne condition. One small advantage of having greasy skin is that it tends to be less easily damaged than dry skin, and less prone to moisture loss. It requires less protection in cold weather; a light oil-in-water emulsion is all that is needed.
Treating oily skin
The essential requirement of treating oily skin is to remove excess surface sebum without total removal of the skin lipids. Severe degreasing treatment can lead to an apparent worsening of sebum secretion, which defeats the aim of the cleansing.
A method of cleansing this type of skin is to wash with a solution of a very mild synthetic detergent (surfactant, see below) containing no oils, waxes or any other lipid agent that could aggravate the oily condition of the skin, sometimes combined with a toning lotion. This kind of product eliminates the oily residue and debris from the skin surface. Some cleansing products contain low concentrations of hydroxy acids (see Reducing Lines and Wrinkles), which remove dead cells from the upper levels of the stratum corneum. They must be used on a regular basis to work adequately. A light moisturizer may be included in the product to counteract any drying effects of the cleanser.
An alternative form now available for facial cleansing is a lathering cloth. This is a growing segment of the cleansing market. Some of the clothes are designed to meet the specific needs of different skin types by delivering multiple skin benefits in addition to excellent cleansing. Due to the form itself, the cloth can contain a low level of surfactants making them mild to skin. These products are still able to generate a generous lather via the cloth structure, which incorporates air as the lather is generated. Being mild while also depositing conditioning agents directly onto the skin helps to improve the skin's overall condition beyond basic cleansing. Lastly, the different cloth textures allow for individualized, but gentle, exfoliation that removes skin flakes for a more even skin surface. These combination of benefits can eliminate the need of other specialty cleansing products, such as toners, make-up removers and exfoliators.