Skin hydration

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The most important function of the skin is the barrier function, that is, the protection of the organism from drying out and from external influences. The outer layer of skin ( epidermis ) naturally plays a special role. It is the contact surface with the environment and must always be flexible and pliable under the most varied of climatic conditions. Here, skin moisture (also called skin moisture) plays a very important role. In the epidermis, it acts like a plasticizer in a system of lipid and protein structures. The skin moisture is regulated by natural moisturizing factors (NMF). These are constantly reproduced in the process of the skin's regeneration.

Normally, the human skin does not need any tools to maintain its natural moisture. However, dry air (especially in winter and in heated rooms) as well as long sunbathing or extensive bathing contribute to excessive deprivation of moisture or loss of natural moisturizing factors. Often there is a feeling of tension and itchy skin. In these cases, cosmetic products (moisturizer, hand cream, body lotion, body milk, aftersun) can compensate or compensate for the loss and thus ensure a corresponding sense of well-being.

The use of strong or alkaline body cleansers can also have a negative effect on skin moisture and disturb the natural balance. Mild cleaning products with an acidic pH value (pH4-6) reduce the stress on the skin during cleaning. The effect of lipid replenishing substances is controversial.

In order to prevent the skin from drying out, air humidifiers have proven effective in heated rooms, especially in winter .

Measurement of skin moisture

There are various measurement methods for determining skin moisture. A widely used method is corneometry , which uses a capacitive sensor to determine the dielectric constant of the skin. Since this depends on the water content of the uppermost skin layers, the measured value is a measure of skin moisture.

The quality of the skin's barrier function can be determined via the transepidermal water loss ( Trans Epidermal Water Loss = TEWL ). This measures the rate of diffusion of water vapor through the skin. As a rule, devices with two sensors for relative humidity and temperature are used for this, which are placed in a diffusion channel at different distances from the skin. From the concentration and temperature differences, the diffusion rate can be determined as mass flow per area and time in g / m² / h.

literature

  • Wilfried Umbach: Cosmetics and hygiene. 3rd edition, Wiley-VCH Verlag, Weinheim 2004, pp. 85ff, ISBN 3-527-30996-9 .
  1. ↑ CW Blichmann, J. Serup: Assessment of Skin Moisture , Acta Derm. Venereol. (Stockli) 1988; 68: 284-290
  2. ^ Nilsson, GE: Measurement of water exchange through skin. Medical and Biological Engineering and Computing, 1977, N. 15, pp. 209-218

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See also