Understanding TEWL is your secret weapon for a healthier, more hydrated skin barrier this winter.

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Hey Reader!

As the weather cools down, your skin goes through a major shift… one that most people feel (tightness, flaking, dullness) but don’t have a name for.

That name? TEWL.

TEWL (Transepidermal Water Loss) is the amount of water that evaporates from your skin into the environment. And in cold, dry air, it skyrockets.
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That’s why fall and winter often trigger:

• Dry, tight-feeling skin
• More visible fine lines
• Irritation or stinging
• A weakened barrier

So Why You Should Care About TEWL (Especially Now)…

Your skin barrier is the gatekeeper of hydration.

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When TEWL rises, your barrier works overtime. And when your barrier struggles… everything else struggles too. Moisture levels, comfort, glow, and even how well your active ingredients perform.

This is why winter is the season to shift your routine. Understanding TEWL gives you the blueprint for protecting hydration at the source, instead of just “moisturizing more.”

The 3 Biggest Winter TEWL Triggers

According to science:

1. Cold weather + low humidity (water evaporates faster)
2. Harsh or over-cleansing (strips essential lipids from the barrier)
3. Skipping occlusives or barrier-supporting ingredients

These aren’t just dry-skin problems; anyone can experience increased TEWL during colder months.

So, How Can You Start Protecting Your Skin Barrier Today

Over the next 9 weeks, we are going to dive into all the ways you can protect your skin barrier, but here’s the quick version:

• Choose gentle, non-stripping cleansers
• Add hydrators that bind water to the skin
• Lock it all in with barrier-supporting moisturizers
• Adjust your routine with the season — your skin needs it

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→ Read the full guide to TEWL (and why your winter skin depends on it)

Want To Learn Even More About The Science of Skincare?

Check out these other articles on RelatableSci.com that break down the science of skincare a little more.

Do you want to read past newsletters? Head over to the archive of all of our previous newsletter series.

​Relatable Skincare Report Archive​

Stay tuned for my next email. And if you found this interesting, share it with a friend! And if a friend sent this to you and it was helpful, subscribe so that you get it delivered to your inbox next week, and a free routine audit guide to say welcome!

​Subscribe and Get the Free Skincare Routine Audit Guide​

→ What winter skin struggle do you want help with?​
Reply to this email and I’ll include it in our upcoming hydration series.

Wishing you a great week,

Allie

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