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When you apply a cream, you perform an action that takes just a few seconds. Behind it lies a process that, for a new product, lasts on average from twelve to twenty-four months and involves chemists, toxicologists, testing laboratories, and a safety assessor. I thought I would tell you about it from the inside, because it is the process I follow closely every day and because understanding it helps explain why some products cost what they do and which promises a cosmetic can actually keep.
It all starts with a problem, not an ingredient
The starting point should never be "let's use this active because it's fashionable", but a concrete question: is there a skin concern that could be addressed better? Only then do you look for the molecule.
The selection of actives draws on scientific literature and documentation from raw-material suppliers. This is where the first distinction is made, and it is worth knowing how to recognize it as consumers too: an active may have independent published studies or only tests conducted by the manufacturer that sells it. Both have value, but not the same value. A serious company states the difference.
The recommended use concentration, the molecule's stability, and its compatibility with the rest of the formula also matter. An excellent active in a test tube may be unusable if it degrades on first contact with light or requires a pH incompatible with the other ingredients. Vitamin C is the best-known example: extremely powerful and notoriously difficult to stabilize.
Formulation: much more than mixing
A formula is not a sum of ingredients; it is a balance. The formulator must keep together:
- pH, which must be compatible with that of the skin and with the activity of the selected actives
- The emulsifying system, which keeps the aqueous and oily phases together
- The preservative system, essential for microbiological safety
- Texture and sensory properties, which are not a luxury: an unpleasant product is not used consistently, and without consistency there are no results
- Delivery, meaning how the active reaches the layer where it needs to act
There is a lot of confusion about this last point. The skin barrier exists precisely to prevent substances from passing through: that is its job. A cosmetic acts on the superficial layers of the epidermis, not "deep down" in the literal sense. Formulations can improve an active's affinity and bioavailability; they cannot turn it into an injectable drug.
Testing: the least-discussed part
It is the longest and least visible phase, and it includes several very different steps.
Stability
The formula is stored at different temperatures (typically 4°C, room temperature, and 40°C) to check that it does not separate, change color, alter its pH, or lose effectiveness over time. Accelerated tests simulate product aging and are used to establish the expiry date and the PAO, the period of use after opening.
Challenge test
The product is deliberately contaminated with microbial strains known to verify that the preservative system eliminates them within set time limits. This is the test that makes a cosmetic safe to open and touch with your fingers for months. People who ask for "preservative-free" cosmetics often do not know that a formula containing water must still pass this test, either with dedicated packaging or with ingredients that protect the formula without being classified as preservatives.
Compatibility with the container
The formula is tested inside the final packaging because some ingredients interact with plastic or metal. This is also why changing the container means repeating the tests: the container is part of the product.
Dermatological tests
Conducted on volunteers under medical supervision, they verify the absence of irritating reactions. This is where the claims "dermatologically tested" and "nickel tested" come from. Be careful of a common misunderstanding: "dermatologically tested" means that the test was carried out, not that the result was excellent. It is a statement about the process, not the merit of the result.
Efficacy tests
These support the claims. They may be instrumental (corneometry for hydration, TEWL measurement for the barrier, image analysis for wrinkles and spots) or based on volunteers' self-assessments. Here too, an important distinction: "90% of users perceived more hydrated skin" is a perception result, not an instrumental measurement. Both are legitimate, but they say different things.
The dossier consumers never see
Before a cosmetic can be sold in Europe, EC Regulation 1223/2009 requires the creation of the PIF, the Product Information File. This dossier contains the qualitative and quantitative composition, raw-material specifications, test results, stability and microbiological data, and above all the safety report signed by a qualified assessor: a professional trained in toxicology, pharmacy, medicine, or chemistry.
The product must then be notified to the European CPNP portal before being placed on the market. Without these steps, it cannot be sold: this is not a company choice; it is the law.
One practical consequence of all this is that in Europe no cosmetic may be tested on animals, neither the finished product nor its ingredients. The ban on finished products dates back to 2004, the ban on ingredients to 2009, and since 2013 it has also been prohibited to sell cosmetics in Europe whose ingredients have been tested on animals. This is why the absence of animal testing is not a distinctive feature of any one brand: it is an obligation that applies to everyone.
What is really changing today
The innovation of recent years lies less in individual ingredients than in how they are selected and combined.
Biotechnological actives (obtained through fermentation or plant cell cultures) make it possible to obtain molecules with consistent purity without depending on agricultural yields. Biomimetic peptides replicate sequences recognized by the skin, acting more like signals than filling substances. And research into the skin microbiome has shifted the goal from disinfection to balance.
The strongest trend, however, is another one: shorter INCI lists. Fewer ingredients, chosen better, at concentrations that make sense. A formula with forty entries on the label and all the actives at the end deserves closer scrutiny.
How to read a label
- Order matters. Ingredients are listed in descending order down to 1%. An active mentioned on the front but listed after the fragrance is present at a low concentration.
- Look for the stated concentration. If a brand is proud of its 10% niacinamide, it will say so. If it does not, you can ask.
- Distinguish perception from measurement in efficacy data.
- Be wary of therapeutic claims. A cosmetic improves the appearance and comfort of the skin. It does not treat acne, psoriasis, rosacea, or dermatitis: these are medical conditions, and the point of reference is a dermatologist.
If you want to explore how individual ingredients work, the cosmetic ingredients guide goes into detail, molecule by molecule.
Why I am telling you this
Understanding the process behind a cosmetic is not just about justifying its price. It helps you choose better: recognize when a promise is realistic and when it is not, and stop changing products every three weeks in pursuit of the latest novelty.
The next time you apply a cream, you will know that behind that action are months of testing, a dossier hundreds of pages long, and the signature of someone who is legally responsible for it.
Elisa Avalle, founder of LeLang Skin Care
