Copper Gluconate is not a Copper Peptide

Everyone makes mistakes. I certainly do, and I think they’re actually an incredibly useful learning experience. For example, I recently misinterpreted the conclusions of an experiment – which was then pointed out to me. Because of this discussion, I became aware of a gap in my understanding of sunscreens and now believe I have a better understanding of the issue.

As a community I think we want to know what the best ingredients, what the best products, and what the best ways to use them are. In order to move towards that goal – we need to be able to confront our mistakes as learning opportunities, not as personal attacks to our ego or ignore them.

There’s a seemingly innocuous error on the Paula’s Choice website, and it’s been there for more than 3 years.

Some wonder if a specific group of peptides – copper peptides (also known as copper gluconate) – are finally the anti-aging answer everyone’s been looking for.

Copper gluconate is not a copper peptide. It’s a relatively small error, but I’m seeing this article sourced and this error has spread. It’d be like if Anthony Bourdain misspoke and said rosé was a type of bourbon…and then a lot of people bought rosé and called themselves Bourbon Lovers. While rosé and bourbon may both be delicious, they are distinct, separate things. One is a wine made from grapes and the other is spirit made from grains.

Most recently it showed up in an article on Popsugar about copper peptides, I was quoted in this article and reached out to its author and let her know about the error and it has since been corrected.

OK, so why isn’t copper gluconate a peptide?

Paula’s Choice gets the definition, mostly correct.

Copper peptides combine the element copper with three amino acids.

There’s a minor error in this as well, and it’s to do with the number of amino acids. A copper peptide is simply a peptide with a strong affinity for copper. There are copper peptides with four amino acids, for example.

As it’s most basic definition, a peptide must contain at least one nitrogen atom. Peptides are made up of amino acids, and amino acids contain an amine group – which is based around a nitrogen.

If we look at copper gluconate, we’ll see that it’s made up of copper associated with gluconic acid. Copper does not contain nitrogen, and neither does gluconic acid.

The chemical formula copper gluconate is C12H22CuO14. This means there are 12 carbons, 22 hydrogens, 1 copper, and 14 oxygens. No nitrogen.

If we look at a copper peptide, GHK-Cu, we’ll see that it’s chemical formula is C14H22CuN6O4. This means it has 14 carbons, 22 hydrogens, 1 copper, 6 nitrogens, and 4 oxygens.

Now just the presence of nitrogens in GHK-Cu doesn’t make it a peptide, but we know for it in order to be a peptide it has to have at least one nitrogen. Hence, copper gluconate can’t be a copper peptide.

I reached out to Nathan Rivas (now at Drunk Elephant) and at the time of Paula’s Choice and he was aware of the mistake, but wasn’t able to fix it.

I get that Paula’s Choice is now a much larger company with investors and many moving parts, but the core values of Paula Begoun was to educate her community on cosmetics, without marketing, and in an unbiased manner.

Each member of The Research Team is personally trained by Paula to honestly and scientifically analyze thousands of product formulations. The team is dedicated to helping you find the absolute best products for your skin.

Every one of the 20 books I’ve written on cosmetics, including the current edition of my book Don’t Go to the Cosmetics Counter Without Me, fulfills my commitment to help women understand when product claims are lying or telling the truth.

This ethos was and has been an inspiration to me, from when I was younger and suffering from acne and seeking out her advice, to when I began researching and working within the cosmetic industry.

I do believe it’s a genuine mistake, but it does have repercussions. Some people have been misinformed, and at its worst may have spent money on a product that they would not have purchased otherwise.

Canadian La Roche Posay Anthelios Sunscreen Ingredients

If you follow my Instagram you’ll know that I’ve been on a bit of a sunscreen bender. I’ve been trying to find a replacement for the Ombrelle Complete Kids SPF 50+. While I like that it has the modern UVA sunscreen filter Mexoryl SX, its cheap price and local availability…the texture leaves me wanting. It is thick, has a slight white-cast, becomes very shiny throughout the day because of its high glycerin content.

I was recently sampled a bottle of the Anthelios Ultra-Fluid Lotion SPF 60 and loved the invisible finish as well as its Mexoryl SX and XL content. I ended up gifting it though, because its high price meant it would not be a product I’d likely to repurchase. I found myself rationing it and probably not using enough to get the protection on the label.

I wanted to see if there were other sunscreens in La Roche Posay’s Anthelios line that had a similar finish but was more affordable. Oddly though, the Canadian La Roche Posay website doesn’t list the ingredients for their sunscreens! So, I headed to my local Shopper’s Drug Mart and took some photos. I’ve transcribed the ingredients here for your reference as well 🙂

The Anthelios XL Melt-In Cream SPF 45 in 100 mL size is not on the Canadian La Roche Posay website, but was available in the Shopper Drug Mart when I visited. The photo I have here is old, the packaging has been updated to match the Anthelios XL Melt-In Cream SPF 60. I’m not sure if this means  it is being discontinued or not.

I’ll be posting a review of the products that I tried shortly, as I’m still in the process of testing one (The Anthelios Mineral Tinted Anti-Aging Primer SPF 50 for the curious!)

Mexoryl SX and XL are two patented sunscreens that are only used in the L’Oreal family of brands which includes La Roche Posay and Garnier Ombrelle. They are similar to Tinosorb S and M, but not the same. They tend to offer better UVA protection, as well as greater photostability, and less skin penetration. 

Anthelios Ultra-Fluid Lotion SPF 50 For Body, 125 mL


Active Ingredients

Homosalate 10%, Oxybenzone 6%, Octisalate 5%, Octocrylene 5%, Avobenzone 3%, Ecamsule (Mexoryl SX) 2%

Other Ingredients

Aqua, Cyclopentasiloxane, Alcohol Denat., Cyclohexasiloxane, Styrene/Acrylates Copolymer, Silica, Dicaprylyl Ether, PEG-30 Dipolyhydroxystearate, Dimethicone, Triethanolamine, Glycerin, Nylon-12, Polymethylsilsesquioxane, Caprylyl Glycol, Dicaprylyl Carbonate, Disodium EDTA, Disteardimonium Hectorite, Dodecene, Isostearyl Alcohol, Lauryl PEG/PPG-18/18 Methicone, PEG-8 Laurate, Phenoxyethanol, Poloxamer 407, Poly C10-30 Alkyl Acrylate, Tocopherol. (Code F.I.L.: C182364/1)


Anthelios Mineral Tinted Anti-Aging Primer SPF 50, 40 mL


Active Ingredients

Titanium Dioxide 25%

Non Medicinal Ingredients

Dimethicone, C12-15 Alkyl Benzoate, Dicaprylyl Ether, Dimethicone/Vinyl Dimethicone Crosspolymer, Talc, Triethylhexanoin, Isohexadecane, Styrene/Acrylates Copolymer, Hydrogenated Jojoba Oil, Aluminum Hydroxide, Stearic Acid, Aluminum Stearate, Alumina, Caprylic/Capric Triglyceride, Cassia Alata Leaf Extract, Diethylhexyl Syringylidenemalonate, Disodium Stearoyl Glutamate, CI 77491, CI 77492, CI 77499 / Iron Oxides, Laureth-4, Maltodextrin, PEG-8 Laurate, Polyhydroxystearic Acid, Silica Silylate, Tocopherol, Aqua. (Code F.I.L.: C179435/3)


Anthelios Dermo-Kids Lotion SPF 50, 150 mL


Active Ingredients

Titanium Dioxide 5.85%, Octisalate 5%, Drometrizole Trisiloxane (Mexoryl XL) 4.5%, Avobenzone 3%, Octocrylene 2.5%, Ecamsule (Mexoryl SX) 1.5%


Aqua, C12-15 Alkyl Benzoate, Alcohol Denat., Caprylic/Capric Triglyceride, Isododecane, Propylene Glycol, Dimethicone, PEG-30 Dipolyhydroxystearate, Glycerin, Lauryl PEG/PPG-18/18 Methicone, Synthetic Wax, Ammonium Polyacryloyldimethyl Taurate, Caprylyl Glycol, Cellulose Gum, Dimethicone Crosspolymer, Dodecene, Glycine Soja Oil, Isostearyl Alcohol, Pentasodium Ethylenediamine Tetramethylene Phosphonate, Poloxamer 407, Silica, Tocopherol, Triethanolamine. (Code F.I.L.: C171811/1)


Anthelios Ultra-Fluid Lotion SPF 60, 50 mL


Active Ingredients

Homosalate 10%, Oxybenzone 6%, Octisalate 5%, Octocrylene 5%, Avobenzone 3%, Ecamsule (Mexoryl SX) 2%


Aqua, Cyclopentasiloxane, Alcohol Denat., Cyclohexasiloxane, Styrene/Acrylates Copolymer, Silica, Dicaprylyl Ether, PEG-30 Dipolyhydroxystearate, Dimethicone, Triethanolamine, Glycerin, Nylon-12, Polymethylsilsesquioxane, Caprylyl Glycol, Dicaprylyl Carbonate, Disodium EDTA, Disteardimonium Hectorite, Dodecene, Isostearyl Alcohol, Lauryl PEG/PPG-18/18 Methicone, PEG-8 Laurate, Phenoxyethanol, Poloxamer 407, Poly C10-30 Alkyl Acrylate, Tocopherol. (Code F.I.L.: C182364/1)


Anthelios Targeted Protection Stick SPF 60, 9 g


Active Ingredients

Octocrylene 10%, Titanium Dioxide 6.25%, Avobenzone 3%, Drometrizole Trisiloxane (Mexoryl XL) 2%


Ricinus Communis, Isopropyl Palmitate, Polyethylene, Isohexadecane, Ozokerite, Theobroma Cacao, Butyrospermum Parkii, Dimethicone, Glycine Soja, Tocopherol. (Code F.I.L. C24262/1C)


Anthelios XL Melt-In Cream SPF 60, 100 mL


Active Ingredients

Octocrylene 10%, Titanium Dioxide 4.15%, Avobenzone 3.5%, Drometrizole Trisiloxane (Mexoryl XL) 3%, Terephthalylidene Dicamphor Sulfonic Acid (Mexoryl SX) 3%


Aqua, Propylene Glycol, Glycerin, Cyclopentasiloxane, Triethanolamine, Isopropyl Palmitate, Stearic Acid, VP/Eicosene Copolymer, Dimethicone, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Aluminum Hydroxide, Carbomer, Disodium EDTA, Glyceryl Stearate, Glycine Soja, Hydroxypropyl Methylcellulose, Methylparaben, PEG-100 Stearate, Phenoxyethanol, Propylparaben, Stearyl Alcohol, Tocopherol. (Code F.I.L.: C15709/2C)

Anthelios XL Melt-In Cream SPF 45, 100 mL


Active Ingredients

Octocrylene 10%, Avobenzone 3.5%, Titanium Dioxide 3.3%, Drometrizole Trisiloxane (Mexoryl XL) 3%, Terephthalylidene Dicamphor Sulfonic Acid (Mexoryl SX) 2%


Aqua, Propylene Glycol, Cyclopentasiloxane, Glycerin, Isopropyl Palmitate, Triethanolamine, Stearic Acid, VP/Eicosene Copolymer, Dimethicone, PEG-100 Stearate, Glyceryl Stearate, Stearyl Alcohol, Phenoxyethanol, Aluminum Hydroxide, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Methylparaben, Carbomer, Hydroxypropyl Methylcellulose, Disodium EDTA, Glycine Soja, Tocopherol, Propylparaben. (Code F.IL.: K17514/3)

Anthelios Lightweight Lotion SPF 60, 100 mL


Active Ingredients

Homosalate 10%, Octocrylene 7%, Octisalate 5%, Avobenzone 4%, Drometrizole Trisiloxane (Mexoryl XL) 2.5%, Terephthalylidene Dicamphor Sulfonic Acid (Mexoryl SX) 0.5%


Aqua, Glycerin, Alcohol Denat., Styrene/Acrylates Copolymer, Dimethicone, Propylene Glycol, PEG-100 Stearate, Glyceryl Stearate, Silica, Synthetic Wax, Phenoxyethanol, Sodium Polyacrylate, Triethanolamine, Stearic Acid, Caprylyl Glycol, Palmitic Acid, PEG-8 Laurate, Xanthan Gum, Tocopherol, Disodium EDTA. (Code F.I.L.: K158295/6)


Anthelios Lightweight Lotion SPF 30, 100 mL


Active Ingredients

Homosalate 10%, Octocrylene 5.5%, Octisalate 5%, Avobenzone 3%, Drometrizole Trisiloxane (Mexoryl XL) 2.5%, Terephthalylidene Dicamphor Sulfonic Acid (Mexoryl SX) 0.5%


Aqua, Glycerin, Alcohol Denat., Styrene/Acrylates Copolymer, Dimethicone, Propylene Glycol, PEG-100 Stearate, Glyceryl Stearate, Silica, Synthetic Wax, Phenoxyethanol, Sodium Polyacrylate, Triethanolamine, Stearic Acid, Caprylyl Glycol, Palmitic Acid, PEG-8 Laurate, Xanthan Gum, Tocopherol, Disodium EDTA. (Code F.I.L.: K158303/4)


Anthelios Mineral Tinted Ultra-Fluid Lotion SPF 50, 50 mL


Active Ingredient

Titanium Dioxide 11%

Non Medicinal Ingredients

Aqua, Isododecane, C12-15 Alkyl Benzoate, Dimethicone, Undecane, Triethylhexanoin, Isohexadecane, Styrene/Acrylates Copolymer, Nylon-12, Caprylyl Methicone, Butyloctyl Salicylate, Phenethyl Benzoate, Silica, Tridecane, Dicaprylyl Carbonate, Dicaprylyl Ether, Talc, Dimethicone/PEG-10/15 Crosspolymer, Aluminum Stearate, Pentylene Glycol, Alumina, Aluminum Hydroxide, Benzoic Acid, C9-15 Fluoroalcohol Phosphate, Caprylyl Glycol, Cassia Alata Leaf Extract, Diethylhexyl Syringylidenemalonate, Disteardimonium Hectorite, CI 77491, CI 77492, CI 77499, Magnesium Sulfate, Maltodextrin, PEG-8 Laurate, PEG-9, PEG-9 Polydimethylsiloxyethyl Dimethicone, Phenoxyethanol, Polyhydroxystearic Acid, Propylene Carbonate, Propylene Glycol, Stearic Acid, Tocopherol. (Code F.I.L.: K50867/4)


Anthelios Mist SPF 50, 155 g


Active Ingredients

Homosalate 10%, Oxybenzone 6%, Octisalate 5%, Octocrylene 5%, Avobenzone 3%, Ecamsule (Mexoryl SX) 2%


Butane, Aqua, Cyclopentasiloxane, Alcohol Denat., Cyclohexasiloxane, Styrene/Acrylates Copolymer, Silica, Dicaprylyl Ether, PEG-30 Dipolyhydroxystearate, Dimethicone, Caprylyl Glycol, Dicaprylyl Carbonate, Disodium EDTA, Disteardimonium Hectorite, Dodecene, Glycerin, Isostearyl Alcohol, Lauryl PEG/PPG-18/18 Methicone, Nylon-12, PEG-8 Laurate, Phenoxyethanol, Poloxamer 407, Poly C10-30 Alkyl Acrylate, Polymethylsilsesquioxane, Tocopherol, Triethanolamine. (Code F.I.L. C182096/1)

KindofStephen around the Interwebs

This blog isn’t the only place that you’ll find me!

I had the chance to hang out at Soko Glam’s office with Charlotte Cho. We chatted about skincare, the future of K-Beauty, and she made sure that I pour my milk in before my coffee!

As you may or may not know, I’m a regular contributor on Soko Glam‘s The Klog


Here are the direct links to my three latest articles on The Klog

The Best Natural Ingredients For Acne
Why Asian Sunscreens Work Better
How Air Pollution Affects Our Skin

I’ve also been interviewed for the following articles

Wendy Rose Gould‘s article on Popsugar

What Are Copper Peptides: This Unexpected Skin Care Ingredient Might Be the Answer to Fighting Wrinkles

Tracy E. Robey‘s articles on Racked

Max Clinic Cirmage Lifting Stick: Can This Viral K-Beauty Product Really Erase Wrinkles?

Oil Washing Could Be the Solution to Your Hair Woes

I’ve also been mentioned a couple of times by The Snailcast podcast by Tracy of Fanserviced, Jude of Fifty Shades of Snail, Chel of Holy Snails, and Cat of Snow White and the Asian Pear!

and finally, K-Beauty retailer OhLolly featured an interview with me! 🙂

I hope you take the time and check out some of the links, and I also hope you keep in mind that these articles may not be as in-depth as the posts on, I have been working on tailoring my writing style to appeal to different audiences – I’d appreciate your feedback!


What lies beneath the “SCIENCE!”

OK, this post is going to be a bit more personal – because frankly this is something that’s been on my mind for quite some time and I think really needs to be discussed.

There’s a big problem in science-based beauty writing – especially from retailers, and I think it boils down to one big issue: Bias.

Science writing has always been difficult. It’s the translation of an experiment or analysis that’s very specific, distilled down to its essential point, and then presented in a way that will attract clicks.

“Moon leaf extract treats acne” is a much more appealing story than “Moon leaf extract reduces ratings on an acne severity grading scale compared to a placebo…in this study on Japanese people…but there was no effect on the Caucasian people in the study…it might also be due to changes in the weather – we don’t know. This is a preliminary study and another group should replicate it to validate our results. P.S. Our moon leaf extract may have been contaminated.”

You tend to lose all the nuances of a study once you summarise it into a single sentence. Often those nuances are important. This is something I worry about when writing for other websites and when I’m quoted in articles. Editors want clean and strong facts, and readers or customers want definitive and clear advice. Now add on to this the issue of bias, when most of us sit down to write we have a goal or idea and, we consciously or not, tend to focus on research that supports it. Writing a piece on green tea? I may read the supportive studies more closely or dismiss and be overly nitpicky with the studies that showed negative or no effect. Promoting a product that contains green tea? That bias presumably becomes stronger.

We’re humans, it’s hard to be impartial. I’m biased, I certainly have conscious ones and I definitely have unconscious ones. Do I like niacinamide based on its research? Or have I spent more time reading about niacinamide because I’ve been told it was well-researched? Do I favour my own formulations over others and do I lose out on improving my own formulations because of this bias?

Cosmetic research as a whole is neither vigorous nor impartial. It’s often funded by the manufacturer or a brand that is promoting its use. Most research on cosmetic ingredients extends to a single study – that will never be replicated. Most cosmetic research isn’t even done on humans – it’s performed on cells, on models, on animals, on plates of plastic. Most cosmetic products are studied in isolation.

It’s really difficult to take this loose, ephemeral, wishy-washy data and give a hard answer – that is unless you’re comfortable leaving out the gaps in the data, confounds, and specific conditions in the study, and unfortunately some science-based writers and retailers are. I get it – it’s not a great feeling to have someone reach out to you for advice and give them an answer that is at its core a long winded sigh of ‘Mayyybbbbeeeeeee’. That I can sympathise with, I can’t sympathise with people or companies who misconstrue or occlude information to position themselves as an expert or to sell a product.

I’m considering taking “skincare expert” out of my headline because I don’t think I am one – I’ve been told an “expert” just needs to know 1% more than the population, but I don’t think that’s enough. I think “expert” implies someone that has answers – and answers I do not have. What I do have is results from other people’s research, an opinion, and a desire to share both.

I want to be very clear: I know there are many writers out there that do seek out research, are curious, do their best to read it, understand it, and explain it to their readers. I also understand that not everyone has journal access or a relevant background. To them, I say get in touch with me – and I will help you get access to the paper and explain concepts. My issue is with the writers and companies who do have access, who twist and misconstrue, who leave out information that doesn’t support their view, those who are satisfied without questioning their conclusions, who write too confidently, who are OK with presenting a question as a fact, and who should know better.

So to my fellow writers, these are my suggestions to help our readers and customers make better beauty and skincare decisions

Clear and functional sources

Be proud of your sources, don’t source-puke a long list of unclickable, poorly formatted text in the hopes that people will be daunted and just trust what you wrote. Don’t just link to the journal’s homepage or a textbook. Take the effort and help people find where you found your information.

We live in the age of Digital Object Identifiers (DOIs), it’s a permanent link that will always point to that resource – even if it gets moved to a new location. Use them! Or at least stick to a style guide for your sources, the ACS style guide is commonly used.


Source and quote material that is relevant to your topic. Don’t source tangential things to try to make your writing look more researched. Was the experiment performed on humans? If not, you should point that out. Was it performed on humans, or animals, or cells? Was it a review of other research?

Often results from experiments on cells or animals are presented in a way to make us expect the same results when applied to our skin. Unfortunately, these results don’t always predict the results we can expect on humans. These types of studies can be useful in discovering how or why an ingredient works the way it does or if it’s possible for an ingredient to work – but they can’t replace results observed on actual people.

A review of ethanol’s effects on liver cells has been presented as evidence that ethanol applied onto the skin will cause the same damage – while there is a possible mechanism, that study isn’t strong evidence. Our skin acts as a barrier, ethanol evaporates quickly, other skin components like hyaluronic acid may reduce the effect, and human skin cells may respond differently than liver cells – these are just some factors that can change ethanol’s effect when put on our skin – but aren’t often mentioned.

Scrutinize yourself

We all make mistakes and we don’t all have editors or peers who can double-check our work. Saying something that isn’t common knowledge or you’re unsure of? Take a quick hop into Google and confirm it, otherwise, you might mischaracterize copper gluconate as a copper peptide.

If you’re citing research, read it! Finding a line that supports your point and skipping the rest of the paper is irresponsible, can be misleading to your readers, and most of all you’ve done yourself a disservice by missing out on some valuable knowledge.

Search broadly

Research is not an easter egg hunt. Searching for “Vitamin C+ Hyperpigmentation” won’t give you an unbiased and complete result. Because of the way paper abstracts and titles are written, searching for “Vitamin C + Hyperpigmentation” will likely only return results where Vitamin C was found to have a positive effect on hyperpigmentation. 

Instead try a broader search like “Vitamin C + Cosmetic”, “Vitamin C + Topical”, or “Vitamin C + Skin”.

Stop “SCIENCING!” the shit out of things

It is absolutely OK to not know something, or to not have an answer, or to have an opinion that isn’t researched. You can be honest with your readers and customers, I think they’ll appreciate that. Your opinions as a person or brand are valuable – as long as they’re transparent. Don’t use science as a veil, science is a process of discovery and learning – not a marketing angle or sales tactic.

“It’s important to keep in mind as you study chemistry or any other science that scientific theories are not laws of nature and can never be absolutely proven. There’s always the chance that a new experiment might give results that can’t be explained by present theory. All a theory can do is to represent the best explanation that we can come up with at the present time. If new experiments uncover results that present theories can’t explain, the theories will have to be modified or perhaps even replaced.”

— John E. McMurry, Chemistry (7th Edition)

Be honest

I think this is something that I can improve on as well. I will try to make it clear when I’m unsure about something and when I come across research that doesn’t “prove my point”.

Along those lines, I’d also like to thank you, the reader,  for your wonderful questions. There are often times when I get a new insight from a question, or it makes me realise that there’s a gap in my understanding.  I would love to give you answers to all of your questions, but I don’t have them. Sometimes I can only show you a map, but I can’t mark out the path. My broad advice is to let go of the notion of a “perfect routine” or “perfect product”. While the search for the perfect routine or skin care product isn’t a mythical quest – we’re not there yet. We don’t even know for sure if it’s better to apply a moisturiser before or after sunscreen – we have some educated guesses, but no strong proof! We’re even further from an answer that would apply to all sunscreen and all moisturiser combinations.

Skincare, as it is now, is a field of ‘maybes’. Maybe some of those expensive and rare botanical extracts have amazing anti-ageing effects and maybe it’s just the glycerin in your lotion that’s making your skin glow. Many skincare questions don’t have real answers yet and there’s even less information on whether or not an ingredient is better than another.

You should think about what your ‘evidence filter’ is set to. Is skincare fun and exciting for you? Do you have the budget and time to try newer and more novel ingredients? Then set your filter wider, enjoy the cornucopia of beautiful and fun products out there. Enjoy the process of applying them to your skin, of searching for them, of reading about other people’s experiences with them.

If that’s not what you want, then set your filter tighter, use ingredients that have more research on them – like a sunscreen with strong UVA and UVB protection and prescription retinoids. Take fewer risks and spend your money on skincare that has been shown to work for most people. You may be missing out on some truly effective ingredients, but you’re also avoiding ingredients that are just marketing.

In the long-run who will benefit more from their skincare routine? The person that seeks out the many novel and exciting products, or the one that picks the few researched and qualified products?

We just don’t know.


“Physical” vs. “chemical” sunscreens and other sunscreen myths

Titanium dioxide and zinc oxide are often categorised as “physical” sunscreens, whereas every other sunscreen used is considered a “chemical” sunscreen.


“Physical” Sunscreens “Chemical” Sunscreens
Zinc Oxide
Titanium Dioxide
Mexoryl SX
Mexoryl XL
Tinosorb S
Tinosorb M

You’ll often find different rules and advice for using “physical” and “chemical” sunscreens. One dermatologist says that you need to apply less physical sunscreen compared to a chemical sunscreen. There’s also the belief that “physical” sunscreens provide protection instantly, don’t absorb into the skin, don’t degrade in the sun, and don’t need reapplication.

These are myths and are not backed by research or chemical knowledge. By following these rules (or myths) you’re not using your sunscreen to its greatest effect!

“Physical” vs. “Chemical”

Dividing sunscreens into “physical” and “chemical” isn’t the best way to do it. These two categories overlap completely. If we were to draw a Venn diagram of the two groups, it’d look like this

Sketch (1)

Chemicals are physical – they have a mass and take up space. On the other end, the “physical” sunscreens titanium dioxide and zinc oxide are chemicals, you can find the elements titanium and zinc on the periodic table.



It’s sometimes explained that titanium dioxide and zinc oxide are suspensions of particles, they don’t dissolve or form solutions like chemical sunscreens. This is true and their even distribution in the sunscreen formula and on the skin is very important – poor distribution can greatly reduce how much UV protection titanium dioxide or zinc oxide can provide on the skin.

However, there are caveats, sunscreens like Tinosorb M (INCI: Methylene Bis-Benzotriazolyl Tetramethylbutylphenol) also exist as particle suspensions – not solutions. Tinosorb M comes as a very fine suspension of particles in water. So, if you were to draw the line based on that you’d have to include Tinosorb M,  a “chemical” sunscreen with the “physical” sunscreens.

What does differentiate titanium dioxide and zinc oxide then? Well, they’re both metal oxides or metals combined with oxygen. Metal oxide sunscreen doesn’t have the same ring to it, but there is another way to describe them.

Inorganic vs. Organic

In marketing, organic is a label that describes how something is produced – often with a safe-list of chemical treatments and approved practices.

In chemistry, organic means the chemistry of compounds that contain carbon. Titanium dioxide and zinc oxide don’t contain carbon. They’re made up of metal and oxygen and classified as inorganic.

Marking the categories as organic and inorganic makes more sense because all of the sunscreen chemicals used contain carbon, except for titanium dioxide and zinc oxide.


Sunscreen Chemical Formula Composition
Zinc Oxide ZnO 1 Zinc + 1 Oxygen
Titanium Dioxide TiO2 1 Titanium + 2 Oxygens
Octocrylene C24H27NO2 24 Carbons + 27 Hydrogens + 1 Nitrogen + 2 Oxygens
Avobenzone C20H22O3 20 Carbons + 22 Hydrogens + 3 Oxygens
Octinoxate C18H26O3 18 Carbons + 26 Hydrogens + 3 Oxygens

Organic and inorganic is also a useful way to categorise sunscreens because the way that the carbon atoms are linked up in organic sunscreens is why they absorb UV energy. If you look at the chemical structure of an organic sunscreen like avobenzone you’ll see that they have single bonds alternated with double bonds.


This alternation or conjugation of the single and double bonds allows the molecule to absorb energy along the electromagnetic spectrum. The amount of conjugation determines which part of the electromagnetic spectrum they absorb, whether that be in the visible spectrum to produce a colour, or in the ultraviolet spectrum to protect our skin from UV.


Inorganic and organic neatly divide the two sunscreen types and are also descriptive. I know most companies won’t want to confuse their customers by labelling their 80% organic-certified sunscreen product with titanium dioxide as inorganic, but at least as sunscreen shoppers we can understand the difference!


Myths about using Inorganic vs Organic Sunscreens


“Inorganic sunscreen and organic sunscreens work differently”

Mostly Myth! It’s often said that inorganic sunscreens (titanium dioxide and zinc oxide) reflect UV off of the skin and organic sunscreens absorb UV and convert it into heat. In reality, for most of the UV spectrum they work very similarly.

Organic sunscreens absorb UV because of the way the bonds between their carbon molecules are arranged. The number of bonds between the carbon atoms in the sunscreen molecules and their conjugated arrangement give sunscreens their absorptive properties in the UV region of the electromagnetic spectrum. Remember that conjugated means alternating single and double bonds!

The energy from UV light promotes electrons in the conjugated carbon bonds of organic sunscreen molecules from a lower energy state to a higher energy excited state. The excited electrons in the bonds then relax or release the absorbed energy by stretching, vibrating, or bending – this turns that energy into heat.

In some cases, the organic sunscreen chemical can’t relax and release the absorbed energy by bending, stretching, or vibrating and the absorbed energy causes a change in its structure. This is what happens with avobenzone, it absorbs the UV energy and instead of relaxing, it changes its structure – and this new structure formed from avobenzone doesn’t absorb UV energy as well. As more and more avobenzone molecules’ structures change, the less UV energy is absorbed by the sunscreen formula. Some of the new structures formed from avobenzone are also more irritating and sensitising to the skin. Photo-stabilizers prevent this from happening by absorbing the energy from excited avobenzone and releasing it before its structure can change.

Inorganic sunscreens work the same way – even though their structure is different from organic sunscreens. Metal oxides, like titanium dioxide and zinc oxide, have solid structures made of alternating sheets of metal and oxygen atoms. The principle behind the UV protection is exactly the same as organic sunscreens. Instead of the arrangement and amount of carbon bonds, the particle size of the titanium dioxide or zinc oxide determines which parts of the electromagnetic spectrum it absorbs.

There is a strong belief that these inorganic metal oxide sunscreens act by reflecting UV light instead of absorbing it, but this isn’t the complete story. UV light is divided into UVB and UVA. UVB is between 280 to 315 nm and UVA is between 315 to 400 nm. Inorganic sunscreens predominately absorb in the UVB spectrum and reflect in the long UVA (above 360 nm) and visible spectrum. Only about 5% of UVB light is reflected by inorganic sunscreens and the remainder gets absorbed and converted – just like organic sunscreens.

The results of a measurement show how much energy is reflected by different types and sizes of titanium dioxide. The horizontal scale represents the electromagnetic spectrum with my yellow highlight marking the UV spectrum. The vertical scale represents how much of the energy is being reflected, the higher up on the chart – the greater the amount of reflection.

titanium dioxide2

Between 250 nm and 350 nm titanium dioxide reflects less than 10% of the energy. Between 350 nm and 400 nm there is more reflection depending on the form of titanium dioxide and the particle size. The anatase form of titanium dioxide exhibits more reflection than the rutile form of titanium dioxide. These forms have to do with the way the titanium and oxygen atoms are arranged in the titanium dioxide. Sunscreens often use rutile titanium dioxide because they are safer and less reactive.

The same is seen with zinc oxide, with most of the reflection being above 350 nm. The rest of the UV spectrum is absorbed.

zinc oxide

The high reflection above the UV spectrum (above 400 nm) into the visible light region of the electromagnetic spectrum is what causes the whitening effect and flashback when using inorganic sunscreens.

“You can use less of an inorganic sunscreen compared to an organic sunscreen”

Myth! All sunscreens are tested at the same density, which is 2 milligrams of sunscreen per square centimetre. That applies to inorganic, organic, spray, stick, lotion, wipes, etc.

If you want to get as close as possible to the protection on the label of the sunscreen product, you need to apply it at the same density it was tested at.


“Inorganic sunscreens sit on the skin. Organic sunscreens absorb into the skin”

Myth! Think of it this way, if we want to protect ourselves from the rain we need to hold the umbrella above our heads. Sunscreens work the same way, you want them to absorb the energy before they can reach our skin cells, particularly the living cells. The most effective way for this to be done is to have them on the surface of the skin in a continuous and even layer.

Both organic and inorganic sunscreen particles can penetrate into the upper layers of the skin. If and how much they penetrate is dependent on properties like their particle or molecular size as well as the overall sunscreen formula. This isn’t a desired effect and formulators work to reduce the amount that penetrates. Modern organic sunscreens often have larger molecular sizes, chemical and physical properties, or even coatings which make it more difficult for them to penetrate past the surface of the skin.

Keep in mind that skin penetration doesn’t mean that it’s causing harm to our bodies. There has to be a biological mechanism for it cause an effect. There is a lot current and ongoing research into this area, but we don’t have any strong answers yet.


“Inorganic sunscreens provide protection right away. Organic sunscreens need to activate on the skin”

Myth! Organic sunscreens and inorganic sunscreens absorb UV due to their electronic properties. There’s no activation or chemical reaction that occurs on the skin with organic sunscreens to create photoprotection.

We know this is true because we can measure how much UV is absorbed by an organic sunscreen off of the skin, like on a piece of clear plastic. Organic sunscreens will also prevent UV colour changing bracelets, beads, or stickers from changing colour.

Both inorganic and organic sunscreens will provide UV protection as soon as they’re placed on the skin. The reason why a wait time is part of the application instructions is to allow the sunscreen formula time to dry and form a film on the skin. This makes it harder for it to be wiped off and it also means it can dry to as even of a film on the skin as possible.

The more evenly distributed the sunscreen is on the skin, the more even the coverage and the greater the average protection. If we take 10 umbrellas and hold them over one person, that one person may remain very dry during a downpour but everyone else will get soaked – if we distribute the umbrellas evenly more people will remain dry. Photoprotection works the same way, it’s measured as an average – you don’t want some areas of the skin with more sunscreen and greater coverage at the expense of other areas with less sunscreen and less coverage.


“Inorganic sunscreens don’t need to be reapplied”

Myth! All sunscreens should be reapplied if you want to maintain photoprotection throughout the day. While it’s true that titanium dioxide and zinc oxide don’t change structure under normal UV radiation, that’s true for many organic sunscreens and sunscreen formulas as well.

The reason why reapplication is recommended is because we often don’t apply enough in the first place and it’s constantly being removed from our skin. Reapplication helps ensure that we have a minimum density of 2 milligrammes per square centimetre of sunscreen on our skin and that we maintain that density throughout the day.

We may not be conscious of removing our sunscreen, but touching our skin, putting on and taking off clothing, using our phones, sweating, eating…all these things will remove some of the sunscreen from our skin. Think about how the coverage of a foundation or lipstick changes throughout the day.

There is no clear answer as to when you should reapply your sunscreen. We all do different things throughout the day in regards to our skin, so the amount of sunscreen removed from the skin will differ from person-to-person and day-to-day. That’s why it’s difficult to have a single rule that will apply to everyone. Conclusions from studies vary in their recommendations for when and how often to reapply.

What you choose to do is up to you, but you should take into account how much UV you’re exposed to, how much you expect to be exposed to, and your activities. You should think about reapplying your sunscreen before going for a jog outdoors. Work in an office? Maybe reapply before you leave the office. What’s clear though is that you should definitely reapply after sweating, swimming, bathing, and abrasion (like laying on sand) – even if you are using a water-resistant sunscreen.

In the UK many sunscreens are marketed as ‘once-a-day’, but health organisations recommend disregarding that and still reapplying throughout the day.

I hope this post has helped you understand why calling some sunscreens “physical” and others “chemical” isn’t as descriptive as it could be, as well as why inorganic and organic sunscreens should be used the same way. Sunscreen is an important part of a skincare routine, and there’s a lot of conflicting advice on how to best use it. Understanding some principles will help you make sense of what is good advice and poor advice when it comes to sunscreen.

I’d also like to thank my friend Jonathon Moir for his help in editing this article.

Vintage skincare and beauty!

The Smithsonian museum has made their archive of historical beauty products public! The collection contains photos and information on balms & salves, as well as make-up, fragrances, and more.

Perusing the collection is a wonderful way to spend a Sunday afternoon, and it’s really interesting to see how products and design have changed – or haven’t.

Smith’s Rosebud Salve still looks the same, for example.


Smith’s Rosebud Salve

For “Chapped lips, face and hands, minor burns and scalds, bites and stings of non-poisonous insects”



Mentholatum, now owned by Japan’s Rohto (the makers of those minty-fresh eyedrops) is famous for their lip balms, decongestant rub, and ointments for sore muscles.


Mentholatum Tin

“Try Mentholatum for Head Colds, After-Shaving, Chapped Skin, Cracked Lips, Sunburn, Burns”



Yardley is one of the first companies to specialize in beauty products, established in 1770.


Yardley Complexion Milk

“A liquid skin cream, smooth & refreshing. Brings elasticity & lustre to a dried skin and forms a perfect face powder base.”



Petrolatum was “discovered” by Robert Chesebrough, after he noticed oil field workers rubbing the jelly on their hands to help heal wounds.


Vaseline Tube



Maybelline was commercialized by a 19 year old boy after he noticed his sister, Mabel, mixing vaseline with coal tar and using the mixture to coat her lashes.



Maybelline Cake Mascara



Gel cream blushes are making their way back into popularity, but this one was made back in the ’70s by Love Cosmetics, which was owned by a company which later became GlaxoSmithKline.


Love’s Cheek Gel in Pink Bronze



This liquid hose was meant to even out the skin tone of the legs, much like Sally Hansen’s modern aerosol version.


Vida-Ray Liquid Hose, Toasted Beige


I found an advertisement for this product in the 1945 Milwaukee Journal. During World War II, cosmetics became a luxury and some women used gravy browning to replace the now rare liquid hose.





There’s so too many other interesting finds to go through them all, but I’ve put some of my other top picks in this gallery.


One Hundred Assorted Beauty Spots by Johnson and Johnson
Zuane La Parot Rouge, Medium by Zuane Parfumers
Chen Yu Cloud Silk Make Up, Light Lotus #1 by Richard Hudnut
Jergens Face Powder, Pink Frosting by Andrew Jergens Company
Pond’s Make-up Pat, Peach by Pond’s Extract Company
Pearlized Chili Pepper Nail Hardener Enamel
Emile Mascara Remover
Airspun Face Powder, Suntan Golden Tone by Coty
Touch & Glow Liquid Makeup, Sun Bronze by Revlon
Pure Magic Super Cover Stick, Natural Fair by Max Factor and Company
Mary Kay Lip and Eye Palette by Mary Kay Inc., made in 1964