The Formulator's Notebook: Salomé Vasseur
Dr. Salomé Vasseur · Botanical formulation chemist & clean beauty consultant · Atelier Vasseur · Paris, France Independent lab and consultancy · Paris 11e | Length: ~1,670 words
Atelier Vasseur occupies two rooms above a courtyard off the rue Saint-Maur: one is a proper lab, stainless and unromantic, and the other has a Persian rug, a wall of amber jars, and a window that will not close properly. Salomé Vasseur has spent eleven years in industrial cosmetic chemistry and six as the person independent founders call when their beautiful idea will not emulsify. She is the least sentimental person in clean beauty, which is precisely why the sentimental brands hire her.
You came out of large-scale industry. Most people go the other way.
They do, and I understand why — the story is nicer in that direction. Mine is less noble. I spent my twenties in a very large group, in an actives department, and I was extremely good at it and quite unhappy. Not for ethical reasons, I want to be clear. The chemistry there is superb. Some of the best formulators in the world are sitting in those labs and nobody outside ever hears their names.
What I couldn't tolerate was the distance. I would work eighteen months on a system, hand it over, and watch marketing build a story around it that had almost nothing to do with what the molecule actually did. And then the story would sell, and the story would get repeated back to me by my own mother. That's a strange feeling — being the source of a thing you no longer recognise.
So I left, and I started taking on small founders, and for the first two years I was mostly poor and permanently covered in shea. But the distance closed. Now when someone tells me their oil is beautiful I can say "yes, I built the ratio, here is why it feels like that." That's the whole reason.
What does the word "clean" actually mean to you, professionally?
Honestly? Very little, as a technical term. It has no regulatory definition, it's assembled mostly from exclusion lists, and some of those lists are built on genuinely bad science. I've had a founder ask me to remove a preservative system that was keeping their product safe, because a blog had frightened their community. That's not clean. That's dangerous, and it's the part of this industry that makes chemists roll their eyes.
But — and this is the part my colleagues get wrong — the impulse behind the word is completely sound. People are asking: is this necessary, is this well-sourced, is this honest, can you tell me what it does. Those are excellent questions. The vocabulary is imprecise; the instinct is correct.
So the way I work is that I translate the instinct into criteria that mean something. Instead of "no synthetics," I ask: is each ingredient here doing a defined job, and is there a version of this formula with fewer ingredients that performs the same? Instead of "natural," I ask: what is the actual origin, what is the extraction method, and what is the batch variability — because a natural extract is a variable input and most young brands don't plan for that. Instead of "non-toxic," which is a meaningless phrase given the entire discipline is dose-dependent, I ask what the exposure is, on what skin, how often.
That's less exciting on a label. It's much better skincare.
When you assess a formula for a brand, what makes one stand out?
Restraint, almost always. I can tell within thirty seconds of reading a list whether the formulator was making decisions or collecting ingredients.
The tell is what I call the passenger problem. You'll see a serum with fourteen botanical extracts, each at a fraction of a percent, and every one of them is a passenger — present so it can be named on the front of the box, contributing nothing measurable. A formula with four ingredients at meaningful levels will outperform it every time, and it will be more stable, and it will be less likely to sensitise someone. But it looks emptier, so it takes a brave founder.
The second thing I look for is whether the texture is doing work. This is underrated to the point of insult. Texture is not packaging for the actives — texture is an active, in the sense that it determines whether the product is used, how much is used, and how the skin behaves in the twenty minutes after application. An oil that absorbs badly will be under-applied forever. A balm that drags will be abandoned. I spend more time on sensorial than on hero ingredients and I make no apology for it.
And third, in fragrance and body care especially: does the scent have a structure, or is it just a smell? There is a great deal of clean fragrance that is one accord, pleasant, and completely flat — it smells the same in minute one and minute forty. The good ones move. A green tea that opens cold and dries down with something creamy and vegetal underneath, or a monoï that starts almost edible and ends up skin-like and warm. Movement is craft. You can feel it even if you have no vocabulary for it.
What are you seeing shift in the French market specifically?
France is a peculiar market for this conversation because we have the oldest, deepest pharmacy culture in Europe, and that culture has done something interesting — it has made French consumers simultaneously the most sophisticated and the most conservative.
The sophistication shows up as ingredient fluency. My neighbour, who is seventy-four and has never worked in this industry, will tell you about her acid. That's normal here. What that means for clean brands is that the "free-from" pitch lands badly — a French customer's first question is not "what's not in it," it's "what does it do, and what's your evidence." Efficacy first. Always.
The conservatism shows up as loyalty. It is genuinely hard to move a French woman off a product she has used for fifteen years, and clean brands often mistake this for a lack of interest. It isn't. It's that the burden of proof is higher.
What's actually shifting, and quickly: the category order of adoption. Five years ago someone experimenting with clean beauty started with face care, which is the hardest place to switch and the easiest place to be disappointed. Now they start with body and fragrance. Body care has become the front door — an oil, a rich cleansing product, something for the hands — and it works because the risk is low and the pleasure is immediate. You cannot really be disappointed by a good body oil. Once someone has had that pleasant experience twice, they'll try the face.
The other shift is that fragrance has quietly become the most demanding clean category in France, which nobody predicted. French customers will forgive a mediocre serum before they'll forgive a mediocre scent. The bar is brutal. But the brands clearing it are seeing loyalty that the skincare side would kill for.
Your own routine — what does a chemist actually use?
Less than you'd think, and much of it unbranded because half of it is mine.
Morning: nothing on the face but a light fluid and sun protection. I'm quite boring about sun protection and quite loud about it. It is the only genuinely non-negotiable product in this entire industry and everything else is a preference.
Evening: an oil-based cleanser, because I wear makeup and I do not enjoy the ritual of struggling with it. Then either a single acid, twice a week, or an oil, the other five nights. Never both. People vastly over-treat.
The thing I would not give up is the body oil, applied on damp skin. There's a real technical reason — you get occlusion over a hydrated surface, so it performs better than the same oil on dry skin, and most people apply it wrong. But the honest reason is that it's four minutes at the end of the day when I'm not thinking about anything. I've formulated things all my life and I still find that a bit magical.
My holy-grail categories: a well-built balm or oil cleanser, one facial oil with a short list, one acid, one sun product, and a body oil with a scent that has some structure to it. Six things. I've formulated hundreds and I own six.
One piece of advice for someone transitioning to clean skincare or fragrance?
Change one thing at a time, and keep the old product.
I'm serious about the second half. Everybody throws everything out in a fit of enthusiasm, has a bad three weeks, and has no baseline to return to and no way of knowing what caused what. Change one product. Wait a month. If it's better, keep going. If it's worse, you know exactly which one.
And for fragrance, specifically: never buy on the first ten minutes. Never. The opening is the part that's designed to sell you, and it's the part you'll spend the least time living with. Wear it on skin — your skin, not a paper strip — and make a decision at hour four. Half of what people call "clean fragrance doesn't last" is actually just a well-built dry-down that they never stayed around for.
The Quick-Fire Round
Morning or evening routine? Evening, without hesitation. Morning is a defence. Evening is a repair.
Scent notes that define you? Vetiver and something green and slightly bitter over it. And, embarrassingly, patchouli — I resisted it for a decade on principle and lost.
The ultimate skincare rule you live by? Fewer ingredients, higher standards, longer timelines. Three rules, but they only work together.
Your current beauty obsession? Ylang. It has been unfashionable for twenty years because of what the eighties did to it, and it is one of the most complex naturals we have. It's coming back and I feel vindicated.
