Trans-Epidermal Water Loss
Trans Epidermal Water Loss (or TEWL) is the rate at which your skin loses moisture, a factor notoriously difficult to quantify – and frequently the source of both dryness and oiliness. One of the many concerns we hear is that the skin may be dry but also too oily. Ever wondered about this paradox? Often, dryness and oiliness coincide as the skin works to compensate for high level moisture loss, that is, your skin could be well-hydrated but losing too much water through evaporation. By assessing the incidence of TEWL we can right this balance with adjustments to your moisturising and skincare routine. If your TEWL readings are high we can advise on skin care that not only hydrates the skin but also protects it with a layer on top to prevent high TEWL – rectifying the problem of ‘dryness’.
Trans-epidermal water loss (TEWL) refers to the loss of water from the skin into the environment. It is a measure of the skin’s barrier function and its ability to retain moisture. An increased TEWL can indicate dehydrated skin, a damaged skin barrier, or a decreased skin hydration.
Trans-epidermal water loss is measured using various instruments, including:
Tewameter: This instrument uses sensors to measure the difference in water content on the skin surface and in the environment, providing a quantitative measure of TEWL.
Evaporimeter: This instrument uses a temperature-controlled chamber to measure the rate of water evaporation from the skin surface.
Fractometer: This instrument uses a laser to measure the skin’s ability to retain water by measuring the depth of wrinkles created by skin dehydration.
These methods provide a way to quantify TEWL and to monitor changes in skin hydration over time. Measuring TEWL can also help to evaluate the effectiveness of moisturizing products and treatments aimed at improving the skin’s barrier function.
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