Your barrier, not your actives,
decides everything

A barrier that is losing water will make almost any active look ineffective. That is the whole argument, and the data behind it is older than most of the ingredients people argue about.

The measurement

Transepidermal water loss is measured in grams per square metre per hour. On intact skin it sits around 4–8. On a compromised barrier it can double, and every actives routine layered on top is working against that gradient.

What TEWL shows

In our four-week panel, the group using barrier support alone dropped from 13.1 to 8.4. The group adding an exfoliating acid on top dropped only to 11.2 — the acid was not the problem, the order was.

Where actives fit

Actives are not the enemy. They are simply downstream of a barrier that has to hold water long enough for them to matter. Fix the gradient first and the same active starts performing.

References

Every figure above comes from the panel published in our March note. The raw table, including the eleven people it did nothing for, is linked at the end.