INCI Guide (II): Ingredient Groups and their Functions

In the first part of this guide, we learned what INCI is, how to interpret it, and why the order matters. Now, let's go a step further: understanding the function of each ingredient according to its category. Because knowing how to read a list is useful, but knowing what each item does is what allows you to choose with real discernment.

Cosmetic ingredients are grouped by function. These are not rigid categories, as a single ingredient can fulfill several functions at once, but knowing them helps to quickly navigate any INCI list. To understand how these components interact, it is very useful to analyze the product under the logic of galenic formulation; that is, the scientific method that dictates how raw materials are combined to transform into a safe, stable, and easy-to-apply cosmetic.

Below, we review the main groups with a practical guide to identify them, know what to look for, and what you will commonly find on the label. The structure of any formula usually follows this order of functions:

• Vehicles or bases: The physical skeleton that supports the entire product.
• Humectants: Capture water provided by the base.
• Emollients: Condition and soften surface cells.
• Occlusives: Seal the above mixture to prevent evaporation.
• Surfactants: Cleansers and emulsifiers that bind the phases of the formula.
• Actives: Ingredients with specific target actions.
• Preservatives, fragrances, and colorants: The final technical and aesthetic additives.

Vehicles or Bases: The Skeleton of the Formula

The vehicle or base is the main component of any liquid, cream, or gel cosmetic. Its primary function is to serve as a physical medium to dissolve and transport the rest of the components, allowing them to spread homogeneously over the skin and facilitating their penetration.

In conventional cosmetics, the standard vehicle is usually ordinary purified water or fluid synthetic bases derived from silicones and mineral oils. In contrast, natural cosmetics leverage this large space to provide real nutritional value from the very base of the product, replacing simple water with botanical juices or plant distillates that nourish the skin on their own.

Therefore, in the natural cosmetics in our catalog, for products with water or oil bases (such as facial serums), these vehicles constitute between 60% and 80% of the total formula due to pure physical and galenic necessity. For pure vegetable oils, with a single ingredient, it will be 100% of the formula. This is a completely different formulation strategy from our solid cosmetics, which completely dispenses with these liquid components to offer dehydrated alternatives where almost 100% of the weight consists of concentrated active and functional ingredients.

In the INCI, you will usually recognize them in the first positions as: Aqua, Aloe Barbadensis Leaf Juice for hydrating formulas. In the case of our facial serums and oils, you will identify their oily carrier bases under botanical Latin names such as Simmondsia Chinensis Seed Oil (jojoba oil) or Argania Spinosa Kernel Oil (argan oil).

Humectants: Attract water to the skin

Humectants are ingredients that capture water from the environment or from the deeper layers of the skin and retain it in the superficial layers. Their effect is immediate and visible: the skin becomes hydrated, looking smoother and plumper.

The best known is hyaluronic acid, capable of retaining up to a thousand times its weight in water. Glycerin, present in almost any cream or serum, is the most widely used humectant in cosmetics due to its effectiveness and low cost. Betaine, obtained from beetroot or coconut, hydrates with a very mild and well-tolerated profile. Beta-glucan acts similarly but with an added calming benefit for reactive skin.

In the INCI, you will recognize them as: Sodium Hyaluronate, Glycerin, Betaine, Beta-Glucan.

Emollients: Soften and make skin flexible

Emollients fill the spaces between skin cells, smoothing the surface and improving flexibility and feel. They are responsible for that silky skin sensation after applying a product.

Vegetable oils are emollients par excellence: argan, jojoba, avocado, baobab, coconut. Each with a distinct fatty acid profile and a different affinity depending on skin type. Squalane is another highly valued emollient for its ultra-light texture and compatibility with all skin types, including oily skin.

In conventional cosmetics, silicones often fulfill this role: Dimethicone, Cyclopentasiloxane, Cyclohexasiloxane. They provide a very pleasant immediate sensation but form an impermeable layer on the skin without providing real nourishment.

In the INCI, vegetable oils appear with their botanical Latin names: Argania Spinosa Kernel Oil, Simmondsia Chinensis Seed Oil, Persea Gratissima Oil.

Occlusives: Seal and protect the barrier

Occlusives form a protective film on the skin that slows down water loss through evaporation. They are always applied over humectants and emollients, sealing everything applied underneath. They are especially useful for very dry skin, in cold climates, or as part of a nightly routine.

Shea butter is the most versatile natural occlusive: it nourishes, protects, and soothes at the same time. Vegetable waxes like candelilla wax or carnauba wax serve a similar function and frequently appear in lip balms and solid products.

In conventional cosmetics, the occlusive par excellence is petrolatum (Petrolatum), derived from petroleum: very effective at sealing but without any nutritive contribution. Lanolin (Lanolin), of animal origin, was also widely used before the expansion of vegetable alternatives.

Surfactants: Cleanse and emulsify

Surfactants are ingredients with a molecular structure that allows them to act between water and oil, capturing dirt and sebum so that water can rinse them away. They are the basis of any cleansing product.

But not all surfactants are the same. Sulfates, such as Sodium Lauryl Sulfate (SLS) or Sodium Laureth Sulfate (SLES), clean effectively but are aggressive: they excessively remove the natural lipids from the skin and scalp, alter pH, and can irritate. They are responsible for the tight feeling after washing.

Coconut-derived surfactants are the most common alternative in natural cosmetics: Sodium Cocoyl Isethionate (SCI), Coco-Glucoside, Sodium Cocoamphoacetate. They cleanse while respecting the skin barrier, with adjusted pH and without drying. They are the base of syndets and sulfate-free shampoos.

Surfactants also act as emulsifiers: they allow water and oils to coexist in a cream without separating. Without them, lotions and creams as we know them would not exist.

Actives: Ingredients with a specific cosmetic function

Actives are ingredients with a specific biological action on the skin: they stimulate, renew, brighten, strengthen. They justify most of a product's marketing claims, and they also vary most in effectiveness depending on their concentration and the quality of the formula.

Some of the most relevant and well-documented include:

Antioxidants

They protect the skin from oxidative damage caused by pollution, sun, and stress. Vitamin C, astaxanthin, green tea, and pomegranate are examples with a solid scientific basis.

Cell Renewers

They stimulate skin renewal, improve texture, and reduce wrinkles. Bakuchiol and phytoretinol are plant-based alternatives to retinol, with much better tolerance profiles. PHAs and succinic acid gently and controllably renew the skin's surface.

Regulators and Uniformizers

They act on sebum, tone, and the skin barrier. Niacinamide is the most versatile of all: it regulates, unifies, strengthens, and soothes. Combined with N-Acetyl Glucosamine, it complements its action on blemishes and uneven tone. Our niacinamide serum is an example of this synergy between effective actives that enhance their effects in a minimalist and thoughtfully crafted formula.

Tightening and Firming Agents

They improve firmness and density. Kigelia Africana has recognized tightening properties. Aloe vera soothes, moisturizes, and helps maintain elasticity.

Preservatives: Necessary, but not all are equal

Every cosmetic product containing water needs preservatives. Without them, the product would be contaminated with bacteria and fungi within days. Preservatives are not the enemy; they are a technical necessity.

The problem is not their presence, but which ones are used. Parabens (Methylparaben, Propylparaben, Butylparaben) were the industry standard for decades. They are effective and stable, but their link to hormonal disruption has put them under scrutiny, especially in high concentrations or with continuous use. Many brands have removed them, although the scientific debate remains open.

Phenoxyethanol (Phenoxyethanol) is the most common substitute in conventional cosmetics and also in many natural products. In correct concentrations, it is safe, but in excess, it can irritate very sensitive skin.

In well-formulated natural cosmetics, preservatives such as benzoic acid (Benzoic Acid), potassium sorbate (Potassium Sorbate), or alcohol (Alcohol Denat.) are used in functional concentrations. Solid products, as they do not contain free water, need much less or none, which is another real advantage of solid formats beyond the packaging.

Fragrances and allergens: what's behind "Parfum"

The word Parfum or Fragrance in an INCI list is one of the most opaque terms on the entire list. It can hide dozens of different ingredients under a single name, because fragrance formulas are protected as industrial secrets.

Within that fragrance may be components that cause reactions in some skin types: fragrance allergens. European regulations require common ones to be declared when they exceed certain concentrations: Limonene, Linalool, Citral, Geraniol, Eugenol, Cinnamal, among others. Some come from natural essential oils, others are synthetic. Their presence does not mean the product is bad, but it is relevant information for those with reactive skin or a history of allergies.

In conventional cosmetics, artificial fragrances are especially common and complex in composition. In cleaner formulations, individually declared essential oils are used, allowing the consumer to know exactly what they are exposed to.

A product without any fragrance will appear in the INCI without any mention of Parfum, Fragrance, or essential oils. This is the safest option for very sensitive or reactive skin.

Colorants: when color adds nothing

Cosmetic colorants have no function on the skin. They are there to make the product visually appealing, nothing more. In the INCI, they appear with CI codes followed by a number: CI 77491 (red iron oxide), CI 42090 (blue), CI 19140 (tartrazine yellow).

Some synthetic colorants have generated controversy due to their potential irritant or allergenic properties. In natural cosmetics, mineral or plant-derived pigments are used, but in any case, they are dispensable ingredients from a functional point of view. Their presence in an INCI is not a cause for alarm, but their absence is not a loss either.

What does not appear in the INCI

It is worth remembering, as we pointed out in Part I, that INCI has its limitations. It does not indicate exact concentrations, does not distinguish between a cold-pressed virgin oil and a refined one, and does not guarantee the real efficacy of a product. It is a tool for transparency, not a certificate of quality.

Reading the INCI critically, knowing the ingredient categories, and having access to reliable information about each one is what makes the back-label list truly useful. For this purpose, we also have our glossary of ingredients or the Learn More fact sheets.