Tatcha The Dewy Serum
Everything behind the verdicts on this product: the rule that fired for each concern, the three answers and the documents they rest on, every study on the row with the date it was opened, and the versions of the tables that produced them. Nothing here is edited by hand; it is generated from the same records the verdicts are.
The scaleRecommendedGoodSupportingEarly evidenceNot for thisAvoidhow it works
Engine 5.2.0 · rules 0.5.1 · evidence table ev-2026.10-r231 · computed October 13, 2026 · how we decide · the evidence table · the anchors
for Aging
Vitamin C has trial-level evidence for aging but no guideline or regulatory standing yet — promising, short of a recommendation; the other actives here are not yet assessed for it.
The lead active has at least one trial behind it for the concern but no guideline or regulatory standing yet, and is present at a working level. Short of a recommendation.
- Rule
- R9p → Promising. An active with early or mechanistic evidence only; declared at a working strength, or a labelled active or at a plausible but undeclared level; the product’s category job is not a recognised companion to the concern; moderate or strong evidence dots on the carrier’s row.
q1 = plausible · q2 = adequate | plausible · supportive = false · strength = moderate | strong
Why this rule exists: 0.5.0: 'Unproven' beside three filled dots read as one question answered twice with opposite words (7,018 rows). The chip measures standing, the dots measure trial volume; where the row carries at least one RCT or a tier-2 source (moderate dots) and the active is present at a working level, the honest word is Promising. Unproven is reserved for plausible-standing rows with limited or weak evidence, or an under-dosed form. Same rank as Unproven — a bet either way; the dots order them.
Rule R9p decided 4,872 verdicts across the catalog; “Promising” is the verdict on 4,872 of 45,446. The full register. - Carrying active
- Stearyl Glycyrrhetinate + Ascorbyl Tetraisopalmitate
- 1 · Standing
- Plausible — trials support it
- 2 · Form
- Plausible — concentration not declared; read from the position in the ingredient list
- 3 · Tolerability
- Standard tolerability
- Evidence dots
- Moderate evidence
- What readers report
- No reviews read yet for this product. Shown beside the verdict; never blended into it.
- Verdict since
- September 5, 2026 (unchanged across rebuilds since then)
The studies and documents on the row
- Clinical Efficacy of Topical Vitamin C on the Appearance of Wrinkles: A Systematic Literature Review — Journal of Drugs in Dermatology (2023), opened July 16, 2026
- Topical ascorbic acid on photoaged skin. Clinical, topographical and ultrastructural evaluation: double-blind study vs. placebo — Experimental Dermatology (2003), opened July 17, 2026
- Topical L-ascorbic acid: percutaneous absorption studies — Dermatologic Surgery (2001), opened July 16, 2026
- Use of topical ascorbic acid and its effects on photodamaged skin topography. — Archives of Otolaryngology-Head & Neck Surgery (unlisted -> tier 3) — randomized, double-blind, vehicle-controlled hemiface; 19 evaluable; optical profilometry positive; product and vehicle supplied by Cellex-C (1999), opened October 13, 2026
- Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage. — Dermatologic Surgery (tier 2) — n=10, double-blind half-face vs vehicle, clinical photoaging scores; randomization NOT stated; NOT counted (2002), opened October 13, 2026
- Clinical, biometric and structural evaluation of the long-term effects of a topical treatment with ascorbic acid and madecassoside in photoaged human skin. — Experimental Dermatology (tier 2) — randomized double-blind, n=20, 5% vitamin C + 0.1% madecassoside; COMBINATION and comparator not stated in abstract; L'Oreal-group co-authors (inferred); NOT counted (2008), opened October 13, 2026
- Clinical Applications of Vitamin C in Dermatology: A Systematic Review. — Journal of Clinical and Aesthetic Dermatology (tier 3) — studies from 2020 on, 44 included; narrative synthesis, no GRADE, no meta-analysis (2026), opened October 13, 2026
← Back to the verdict All aging products → Disclose a concentration or correct a fact →
for Dullness
Hyaluronic Acid has early or mechanistic evidence for dullness — a reasonable bet, not a recommendation; the other actives here are not yet assessed for it.
The lead active has early or mechanistic evidence only, or is present below a working level. A reasonable bet, not a recommendation.
- Rule
- R9 → Unproven. An active with early or mechanistic evidence only; the product’s category job is not a recognised companion to the concern.
q1 = plausible · supportive = false
Why this rule exists: Plausible-tier actives alone do not earn a recommendation, and 'not for this' would overstate the case against them. 'Unproven' with the evidence dots lets the reader judge the bet (added 0.2.0 after the first shadow run put a 10% niacinamide serum at 'not for this' for hyperpigmentation). 0.5.0: the closing clause reads the other heroes — "nothing else here addresses it" only when every other active has a researched 'none' row; "not yet assessed" when that is the truth. Rows whose dots read moderate or better now reach R9p first.
Rule R9 decided 4,156 verdicts across the catalog; “Unproven” is the verdict on 4,156 of 45,446. The full register. - Carrying active
- Sodium Hyaluronate + Hydrolyzed Collagen + Hydrolyzed Elastin
- 1 · Standing
- Plausible — trials support it
- 2 · Form
- Adequate — concentration not declared; read from the position in the ingredient list
- 3 · Tolerability
- Standard tolerability
- Evidence dots
- Limited evidence
Row checked against its sources on July 17, 2026 (evidence table ev-2026.10-r231). - What readers report
- No reviews read yet for this product. Shown beside the verdict; never blended into it.
- Verdict since
- October 9, 2026 (unchanged across rebuilds since then)
The studies and documents on the row
- Benefits of topical hyaluronic acid for skin quality and signs of skin aging: From literature review to clinical evidence — Dermatologic Therapy (2022), opened July 16, 2026
← Back to the verdict All dullness products → Disclose a concentration or correct a fact →
for Rough Texture
Lactic Acid is a reference standard by mechanism for rough texture; this serum carries it.
A trial-supported active, or a reference standard by mechanism, at a working level; or a first-line active below its studied range.
- Rule
- R5 → Good choice. A supported active (trial-backed, or a reference standard by mechanism); declared at a working strength, or a labelled active or at a plausible but undeclared level.
q1 = supported · q2 = adequate | plausible
Why this rule exists: Trial-supported or guideline-supported active, adequately or plausibly dosed.
Rule R5 decided 9,843 verdicts across the catalog; “Good choice” is the verdict on 10,340 of 45,446. The full register. - Carrying active
- Fermented Hadasei-3 with Lactic Acid
- 1 · Standing
- Supported — its mechanism is established (a reference standard, not a trial result)
- 2 · Form
- Plausible — concentration not declared; read from the position in the ingredient list
Studied range: 5–12%, from the trials on the row; needs leave-on contact; judge it after about 4 weeks - 3 · Tolerability
- Standard tolerability
- Evidence dots
- Limited evidence
Row checked against its sources on July 17, 2026 (evidence table ev-2026.10-r231). - What readers report
- No reviews read yet for this product. Shown beside the verdict; never blended into it.
- Verdict since
- September 5, 2026 (unchanged across rebuilds since then)
The studies and documents on the row
- International Cosmetic Ingredient Dictionary and Handbook — declared function — Personal Care Products Council
- Harry's Cosmeticology / Baran & Maibach Textbook of Cosmetic Dermatology — humectant, emollient and occlusive classification — standard reference text
← Back to the verdict All rough texture products → Disclose a concentration or correct a fact →
for Dehydration
Hyaluronic Acid is a reference standard by mechanism for dehydration; this serum carries it.
A trial-supported active, or a reference standard by mechanism, at a working level; or a first-line active below its studied range.
- Rule
- R5 → Good choice. A supported active (trial-backed, or a reference standard by mechanism); declared at a working strength, or a labelled active or at a plausible but undeclared level.
q1 = supported · q2 = adequate | plausible
Why this rule exists: Trial-supported or guideline-supported active, adequately or plausibly dosed.
Rule R5 decided 9,843 verdicts across the catalog; “Good choice” is the verdict on 10,340 of 45,446. The full register. - Carrying active
- Sodium Hyaluronate + Hydrolyzed Collagen + Hydrolyzed Elastin
- 1 · Standing
- Supported — its mechanism is established (a reference standard, not a trial result)
- 2 · Form
- Plausible — concentration not declared; read from the position in the ingredient list
Studied range: 0.1%, from the trials on the row; needs leave-on contact; judge it after about 1 weeks - 3 · Tolerability
- Standard tolerability
- Evidence dots
- Limited evidence
Row checked against its sources on July 17, 2026 (evidence table ev-2026.10-r231). - What readers report
- No reviews read yet for this product. Shown beside the verdict; never blended into it.
- Verdict since
- September 5, 2026 (unchanged across rebuilds since then)
The studies and documents on the row
- Draelos ZD, Cosmetic Dermatology: Products and Procedures — hyaluronic acid classified as a humectant water-binding agent holding many times its weight in water — reference work
← Back to the verdict All dehydration products → Disclose a concentration or correct a fact →
for Compromised Skin Barrier
This formula carries fragrance — a known trigger for compromised skin barrier — so it is not a fit however good its actives are.
The formula carries a known trigger for the concern — fragrance for rosacea, comedogenic esters for acne, fungal triggers for fungal acne — which decides the verdict before any efficacy question.
- Rule
- R1 → Avoid. The formula carries a known trigger for the concern.
q3 = harsh
Why this rule exists: Safety outranks praise (MASTER-PLAN §1.7). A condition-weighted trigger (multiplier ≥ 2 in condition-fit-matrix) decides the verdict before any efficacy question.
Rule R1 decided 1,307 verdicts across the catalog; “Avoid” is the verdict on 1,912 of 45,446. The full register. - Carrying active
- Squalane + Crambe Abyssinica Seed Oil + Phytosteryl Macadamiate
- 1 · Standing
- Not assessed
No evidence row exists for this active and concern; it is in the research queue. - 2 · Form
- Plausible — concentration not declared; read from the position in the ingredient list
- 3 · Tolerability
- Carries a trigger — fragrance load
- Evidence dots
- Not from a trial row
- What readers report
- No reviews read yet for this product. Shown beside the verdict; never blended into it.
- Verdict since
- September 5, 2026 (unchanged across rebuilds since then)
← Back to the verdict All compromised skin barrier products → Disclose a concentration or correct a fact →
No category-job specification exists for this category yet, so there is no job reading.
A verdict is Dermington’s assessment of how well a product’s ingredients fit a concern — never a claim about what the product treats. Every rule is public and the same for every product; a brand cannot buy a reading. How we decide · what has changed · disclaimer.