Not yet investigated
What we have so far
The barrier measured as grams of water per square metre per hour. It is the only objective number most skincare claims could be tested against, and almost none are.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.