Transepidermal Water Loss (TEWL) – How applying your serum or moisturizer on slightly damp skin can help with better hydration

Since it’s the weekend and I like to reserve my Sundays for a DIY spa day at home, I thought many of you out there might enjoy a little treatment at home as well, even if it’s just a relaxing hot bath.  To make sure, your skin stays hydrated, here’s a little tip:

Transepidermal water loss (TEWL) happens on the skin’s surface when water evaporates.  It is one of the major factors that causes the tightness you feel on your skin after a shower or after washing your face.  At first you feel nicely clean and refreshed, but at soon as you get out of the bathroom and let your skin “air dry” for a minute or two, the tightness kicks in and leaves you feeling uncomfortable and your skin thirsty for hydration.

To prevent any discomfort and dryness of my skin, I don’t let the water on the surface of my skin dry or “evaporate”. Therefore the best thing you can do is, stay in the steamy bathroom and just pat dry your face or body, not allowing it to become completely dry but not leaving it wet either. The right time to apply a body lotion, moisturizer or serum for your face is, when your skin is still slightly damp and warm after showering or washing.  Not too wet (or the product will slide off), and not dry either (the damage has been done, TEWL causing tightness due to loss of hydration).

“Locking in moisture”

Often you will hear people say that this technique helps to “lock” or “seal in the moisture”. I remember hearing this for the first time years ago, in a commercial for a baby oil that was also geared towards adults with dry skin.  It works!  Especially if you use something occlusive like an oil or heavy moisturizer, you will see that it will be absorbed much better by damp skin rather than dry skin.  I have very dry body skin that is prone to excema if not properly hydrated.  And I can testify that, whenever I leave the bathroom to do something quickly, by the time I return to apply lotion, my skin has already dried out and the product does not hydrate the way it does like right after the shower.  I feel it doesn’t absorb well and does not have a long-lasting effect.

Another thing you might notice if you get professional treatments: unless you have very sensitive skin, estheticians like to use steam while cleansing the face before incorporating products with active ingredients. Not only does the warmth of the steam help with relaxing and “opening” your pores, water itself is an excellent penetration helper.  So it helps getting more of the active ingredients into the skin.*

Every skin type needs hydration – even oily skin

TEWL happens with every skin type. Even if you have very oily skin and enjoy the “squeaky clean” feeling after washing your face (which is bad by the way), your skin can still lack water – be dehydrated. So basically underneath the shiny surface that the oil/sebum produces, there can be skin that lacks hydration in the form of water.  This is why everyone should follow this technique to prevent dehydration through TEWL.

In case I got caught up with other things, like applying body lotion first, I like to use a hydrating toner all over my face and pat that in to rehydrate, before applying my serum.

The only time really where I wait for my skin to be “dry” is, when I use a liquid exfoliant that contains some sort of acid for exfoliation.  The reason being, that I don’t want to dilute the potency of the acid.  I also let serums or other treatments sink into the skin completely before applying sunscreen or makeup.

Thanks for reading and do let me know how this works for you!


– Mirjam

* Culp, Judith et al. (2013): Milady Standard Esthetics Advanced, Second Edition. Clifton Park, NY. P. 87.

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