Author: Dr Amanda Oakley MBChB FRACP, Dept of Dermatology Waikato Hospital, Hamilton, New Zealand, 1999.
Everyone likes to feel clean; it's refreshing, invigorating, relaxing and enjoyable. Washing your skin removes excessive oil and unpleasant odours as well as make-up, sunscreens and dirt.
Gently wash affected areas on waking, post-exercise and at bedtime. Wet skin. Apply soap or cleanser to hands, add warm water and work into lather. Massage gently. Rinse thoroughly. Gently pat dry.
These terms are most frequently applied to facial skin, but may apply to other sites as well. To determine your skin type, wash your face and pat dry. Wait for an hour, then press a tissue to your forehead, cheeks, chin and nose. If your face is not shiny and there's no oily residue on the tissue, you have normal skin. If your face looks/feels tight or is flaky and there is no oily residue on the tissue, you have dry skin. If your face is shiny and the tissue reveals an oily residue, you have oily skin. Many people have combination skin: the T-zone (forehead, nose, chin) is oily but the cheeks are normal or dry.
Normal skin has a correct balance of moisture and oils. It is slightly acidic at a pH of 4.5–5.75 (6.5 under the arms). A variety of harmless (commensal) bacteria and yeasts live in low numbers on the skin surface, and may help protect your skin from infection (invasion by more harmful bacteria such as staphylococcus or streptococcus).
Sensitive skin is skin that stings easily, especially during or just after cleansing. Sensitive skin is more likely to be dry and is hyper-reactive, that is, prone to develop dermatitis (itchy bumpy skin). Sensitive skin may be inclined to be red, flush easily or have broken capillaries (telangiectasia).
There is often an underlying skin problem such as:
What do cleansers contain?
There is a wide range of products designed for washing, available as bars, liquids, gels, creams, shampoos, scrubs, masks, cloths and wipes. When designing their products, manufacturers consider mildness, biodegradability, low toxicity, cleansing ability, emulsification, moisturisation, convenience, skin appearance and feel, smell (fragrance) and lubrication. The cost varies greatly — although the ingredients of an expensive product may be similar to an inexpensive one.
Pure water alone is not quite enough: removing dirt, which is fat-soluble (lipophilic) and sticks to the skin, requires a surfactant (surface-active agent). Surfactants may be a soap, a synthetic detergent or a combination. They help determine the product's lathering characteristics, feel on the skin, and how easily it rinses off.
Surfactants often have an electrical charge.
Soaps and cleansers can irritate and result in skin problems. These are rare with modern synthetic detergent products made by reputable manufacturers, if they have been designed for sensitive skin and are used appropriately. Over-washing may have the following effects:
Soap has been made since ancient times, but has been particularly popular for cleansing the body since the mid-eighteenth century when modern manufacturing processes were discovered.
Soap is an anionic surfactant. Soap is made from fat and oil mixed with alkali, forming glycerine and the sodium salt of the fatty acid. The fats required for soap making come from a combination of tallow, grease, fish oil, and/or vegetable oil. In ancient times, the alkali came from ash but today the alkali for solid bar soap is sodium hydroxide. Liquid soaps are made with potassium hydroxide.
The hardness, lathering ability, and transparency of soap vary according to the combination of ingredients.
Synthetically produced detergents (syndets) were developed in the 1950s and are widely available. They are made from a variety of petrochemicals (derived from petroleum) and/or oleochemicals (derived from fats and oils). These hydrocarbon chain sources are used to make the lipophilic end of the surfactant molecule. Chemicals, such as sulphur trioxide, sulphuric acid and ethylene oxide, are used to produce the hydrophilic end of the surfactant molecule.
Compared with soap, syndets:
The manufacturers of hypoallergenic skin cleansers have tried to avoid using substances that are likely to cause contact allergy. Their products are often "fragrance-free" (low levels of masking fragrances are permitted), "mild" and "non-irritating". If you have acne, choose products that are labelled as "oil-free" and "non-comedogenic".
For the US, the FDA states: "If a cosmetic claim is made on the label of a "true" soap or cleanser, such as moisturizing or deodorizing, the product must meet all FDA requirements for a cosmetic, and the label must list all ingredients. If a drug claim is made on a cleanser or soap, such as antibacterial, antiperspirant, or anti acne, the product is a drug, and the label must list all active ingredients, as is required for all drug products."
There are no specific labelling requirements in New Zealand.
© 2018 DermNet New Zealand Trust.
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