Occasional dispatches on acne, barrier repair, and sensitive skin — written with the precision of a lab note, not a marketing brief. When the research is interesting, you'll hear about it.
What this is not
Not a routine. Not sponsored. Not daily. This is occasional, evidence-adjacent, and written by someone who actually read the study.
01 / On this newsletter
"Cosmetic chemistry is not difficult to understand. Most of the time, brands are simply counting on you not to look it up."
Poppy Proof Skin is a newsletter about what's actually going on with acne, barrier dysfunction, and sensitive skin — written by someone with a background in cosmetic chemistry and a high tolerance for reading PubMed abstracts. When there's something interesting in the research, or a formulation question worth answering plainly, an issue goes out.
This is not a clinic. Nothing in this newsletter constitutes medical advice. What it is: accurate, referenced, unsponsored. If a product is mentioned, it's because the formula is interesting — not because of a partnership.
Subscribers include formulation students, dermatology nurses, people who've been told their skin is "difficult," and researchers who want plain-language summaries they can share. If you're here, you probably belong here.
02 / What's covered
BARRIER_FUNCTION.md
The skin barrier: what breaks it, what repairs it, what marketing gets wrong
ACNE_MECHANISMS.md
Acne pathology, comedo formation, and what retinoids actually do
INGREDIENT_AUDIT.md
Formulation close-reads: one product, full INCI, no shortcuts
SENSITIVE_SKIN.md
Reactive skin, rosacea overlap, and the fragrance conversation
EVIDENCE_REVIEW.md
What the studies actually show — annotated, without the spin
On ingredients.
The barrier is not a metaphor. It is a physical structure — and understanding it changes every decision you make about your skin.
— PPS
On formulation
Serums are where the chemistry gets interesting. The vehicle, the pH, the preservative load, the sequencing — each one affects bioavailability. Most people pick serums based on marketing language. This newsletter looks at the formula.
Issues in the Ingredient Audit thread typically take one product, walk through the full INCI list, estimate concentrations where possible, and note what the current evidence says about each active. No shortcuts.
Example: Niacinamide 10% + Zinc 1%
The combination is common. The interaction (zinc chelation reducing niacinamide efficacy at high pH) is less discussed. Issue 07 covers it.
Recent issues
The ceramide ratio question: what the lamellar body research actually says
An annotated walk-through of the 2024 consensus paper on stratum corneum lipid organization and what it implies for ceramide-based topicals.
May 2026
Full INCI on a popular barrier cream: three things that surprised me
The preservative system was expected. The emollient choice was not. The pH range listed on the product page is almost certainly wrong.
April 2026
Niacinamide and zinc: the interaction that most formulation guides skip
At specific pH ranges and concentrations, the chelation effect is real. Here's what the in vitro data shows and what it means for routine sequencing.
March 2026
Contact dermatitis vs. rosacea: a differential checklist that actually helps
The presentations overlap. The triggers differ. The formulation responses are almost opposite. A practical field guide to telling them apart.
February 2026
Three 2025 acne RCTs: what they measured, what they didn't, what you can take from them
Methodology notes, endpoint choices, industry funding disclosures. The studies are good. The press releases are not.
January 2026
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