The Beauty Brains – Episode 415
Title: Low pH Shampoo, Hard Water, Supplement Sunscreen, and More
Date: December 24, 2025
Hosts: Valerie George & Perry Romanowski
Episode Overview
In this science-driven episode, cosmetic chemists Valerie George and Perry Romanowski answer listener questions and bust myths on a range of beauty topics. Major themes include the real effects of low pH shampoos on hair color, the truth about oral supplements marketed as internal sunscreens, the impact of hard water on hair color, safety concerns around topical tretinoin, and practical differences between aerosol and non-aerosol hairsprays. There’s also a glimpse inside the latest industry science at the Society of Cosmetic Chemists Annual Symposium and a rundown of current news affecting beauty consumers.
Key Discussion Points & Insights
1. Inside the Society of Cosmetic Chemists Symposium
[02:13–08:44]
- Both hosts attended the annual SCC Scientific Symposium in New York, now vice presidents of the national organization.
- Science vs. Marketing: Many presentations felt heavy on product hype, light on meaningful scientific data (e.g., K18 peptide presentation lacked binding efficacy details).
- Valerie [04:20]: “You talk about this peptide and how it sticks to hair, but how well does it stick? … There’s a specific scientific metric … and he basically was like, ‘Oh, you wouldn’t need to know that.’ … which tells me you either didn’t do the testing or the data’s not impressive.”
- New technology highlights:
- Living Ink: Colorants derived from algae, currently limited to producing black via pyrolysis—“could be a new mascara color” [06:05].
- Small RNA actives: Next trend in skincare, some consumer concerns link this with RNA vaccines.
- Disconnect between academic research and industry needs is evident, with student presentations occasionally lacking basic product context.
2. Beauty Industry News
[09:15–18:12]
- FDA Withdraws Proposed Talc Testing Rule ([09:34–11:42]):
- FDA pulling back on old directive for asbestos tests in talc, likely to re-examine methodology rather than relax safety standards.
- Valerie [10:03]: “It turns out, like, the methodology is really important. … I think the way the prior guidance was written is not very good.”
- Conditioner Science:
- Study using electrokinetics claims behentrimonium chloride is the “best” hair conditioner for adherence, but Valerie calls the method too simplistic.
- Valerie [13:57]: “It just matters about the consumer perception.”
- New Sunscreen Ingredient Endorsed (Bemotrizinol):
- FDA is close to approving this EU-favorite broad-spectrum filter for US OTC sunscreens.
- Should improve sunscreen formulation options; minimal skin absorption.
- Perry [16:46]: “This is a new UVA blocker ... opens up a whole new avenue.”
- Noted: All sunscreen actives have been animal tested.
Listener Q&A
Q1. Low pH Shampoos for Color Protection
[18:19–20:35]
- Claim: Low pH shampoos preserve hair color by keeping cuticle closed.
- Reality:
- Most shampoos pH 4.5–6.5; during washing, shampoo is diluted to near-neutral by water anyway.
- Color loss is more affected by surfactant type and concentration, not pH.
- Valerie [19:03]: “The pH is never really that low ... what types of surfactants are present ... those are the types of things that are going to pull the color out of your hair.”
- Perry [20:23]: “I also don't think the pH has much to do with whether you're opening the cuticle or not. Once the hair gets wet, it swells up and the cuticle is going to open up.”
Q2. Do Oral Supplements Like Polypodium Leucotomos Provide Sun Protection?
[20:35–24:45]
- Claim: Supplements offer measurable SPF value.
- Reality:
- No reliable evidence for real SPF equivalence from oral supplements.
- Polypodium leucotomos (a fern extract) contains antioxidants; at best, might reduce inflammation or help DNA repair.
- Supplements metabolize differently in each body; liver impact is a concern.
- Perry [22:20]: “There's not really any valid SPF equivalent for an oral product … there's no real SPF value you can give to a supplement like this.”
- Valerie [23:12]: “I just get really nervous about taking too many plant extract supplements.”
- Best practice: use topical SPF and basic antioxidants if desired.
Q3. Hard Water’s Effect on Hair Color
[24:50–29:48]
- Effects:
- Hard water (high in calcium/magnesium, possibly iron/copper/lead) affects hair most when it’s already chemically damaged.
- Can make hair dull or shift shade if metal ions build up—but only an issue with extreme water and very porous hair.
- Best approach: Use a chelating treatment (Malibu C, L’Oreal Metal Detox) occasionally, not daily.
- Valerie [26:57]: “It's only a problem if you bleach your hair pretty much ... then it's a problem. But if you have pretty healthy hair, hard water is less of a problem.”
- Modern shampoos work well even in hard water, unlike traditional soap.
Q4. Is Topical Tretinoin Linked to Intracranial Hypertension?
[29:51–37:11]
- Background: Oral retinoids (like isotretinoin) are established risk factors.
- Topical Use:
- Only a handful of case reports (worldwide, single digits), often with other risk factors present.
- Blood absorption from topical tretinoin is minimal to undetectable.
- No large studies show population-level risk.
- Perry [32:25]: “There are just a very small number of cases … frequently, they had other risk factors … there are no large epidemiological studies.”
- Valerie [35:56]: “It is always amazing to me how little we really know when it comes to medicine and treatments in general.”
- Conclusion: Not a meaningful risk for the average user.
Q5. Aerosol vs. Non-Aerosol Hairsprays
[37:18–40:57]
- Aerosol: Minimal water, mostly propellant; dries on the hair instantly. Preferred by professionals for finishing styles.
- Non-aerosol: Water-based, leaves hair wet, less desirable for holding finished styles.
- Regulations increasingly limit allowable propellant content (VOC limits).
- Valerie [37:39]: “You can’t finish the hair when you make it wet again … non-aerosol hairsprays are just not as desirable.”
- California is restricting both fragrances and VOCs; Europe less so.
Notable Quotes & Memorable Moments
- On industry presentations:
- Valerie [04:20]: “You talk about this peptide and how it sticks to hair, but how well does it stick? ... which basically tells me you either didn't do the testing or the data's not impressive.”
- On consumer perceptions of conditioning:
- Valerie [13:57]: “At the end of the day, it just matters about the consumer perception.”
- On oral supplements for sun protection:
- Perry [22:20]: “There's not really any valid SPF equivalent for an oral product.”
- On tretinoin and rare side effects:
- Perry [32:25]: “There are just a very small number of cases ... there are no large epidemiological studies.”
- Valerie [35:56]: “It is always amazing to me how little we really know when it comes to medicine and treatments in general.”
- On why stylists prefer aerosol hairspray:
- Valerie [37:39]: “You can’t finish the hair when you make it wet again … non-aerosol hairsprays are just not as desirable.”
Timestamps for Key Segments
- SCC Symposium Recap: 02:13–08:44
- Talc, Conditioner, and Sunscreen News: 09:15–18:12
- Low pH Shampoo & Color: 18:19–20:35
- Supplement Sunscreens – Polypodium Leucotomos: 20:35–24:45
- Hard Water & Hair Color: 24:50–29:48
- Tretinoin & Intracranial Hypertension: 29:51–37:11
- Aerosol vs. Non-Aerosol Hairspray: 37:18–40:57
Original Tone & Delivery
- Friendly and informal, with plenty of real-world skepticism toward industry hype.
- Valerie and Perry’s delivery is dry-humored, honest, occasionally nerdy, and always science-first.
- Strong encouragement for listeners to be critical, informed consumers.
Bottom Line
The Beauty Brains continue their mission of myth-busting with detailed, scientific answers and a transparent look at both industry and regulatory developments. Topics covered this week demonstrate how much more nuance and real-world testing is needed for the claims we see on beauty products—and how consumers are best-served by skepticism and simple, proven basics: use SPF, trust your own hair’s response, and don’t believe everything you read on a beauty label.