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Kerastase Serum Extentioniste

Serum Extentioniste

Stimulates the growth of strong healthy hair follicles
Uploaded by: javo on

Kerastase Serum Extentioniste
Ingredients explained

Also-called: Aqua;Water | What-it-does: solvent

Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product. 

It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water. 

Once inside the skin, it hydrates, but not from the outside - putting pure water on the skin (hello long baths!) is drying. 

One more thing: the water used in cosmetics is purified and deionized (it means that almost all of the mineral ions inside it is removed). Like this, the products can stay more stable over time. 

What-it-does: viscosity controlling

A cationic polymer molecule (a big molecule with repeated subunits and a positive charge) that acts both as a film-former and conditioning ingredient as well as a thickening agent

Also-called: Mineral Oil;Paraffinum Liquidum | What-it-does: emollient, solvent | Irritancy: 0 | Comedogenicity: 0-2

The famous or maybe rather infamous mineral oil. The clear oily liquid that is the "cheap by-product" of refining crude oil and the one that gets a lot of heat for its poor provenance. It is a very controversial ingredient with pros and cons and plenty of myths around it. So let us see them:  

The pros of mineral oil
Trust us, if something is used for more than 100 years in cosmetic products, it has advantages. Chemically speaking, cosmetic grade mineral oil is a complex mixture of highly refined saturated hydrocarbons with C15-50 chain length. It is not merely a "by-product" but rather a specifically isolated part of petroleum that is very pure and inert.

It is a great emollient and moisturizer working mainly by occlusivity. Occlusivity is one of the basic mechanisms of how moisturizers work and it means that mineral oil sits on top of the skin and hinders so-called trans-epidermal water loss, i.e water evaporating out of your skin. When compared to heavy-duty plant oil, extra virgin coconut oil, the two of them were equally efficient and safe as moisturizers in treating xerosis, a skin condition connected to very dry skin.

The other thing that mineral oil is really good at is being non-irritating to the skin. The chemical composition of plant oils is more complex with many more possible allergens or irritating components, while mineral oil is simple, pure and sensitivity to it is extremely rare. If you check out the classic French pharmacy brands and their moisturizers for the most sensitive, allergy prone skin, they usually contain mineral oil. This is no coincidence. 

The cons of mineral oil
The pros of mineral oil can be interpreted as cons if we look at them from another perspective. Not penetrating the skin but mostly just sitting on top of it and not containing biologically active components, like nice fatty acids and vitamins mean that mineral oil does not "nourish" the skin in the way plant oils do. Mineral oil does not give the skin any extra goodness, it is simply a non-irritating moisturizer working mainly by occlusivity. 

The myths around mineral oil
Badmouthing mineral oil is a favorite sport of many, it is a cheap material and being connected to petrolatum makes it fairly easy to demonize. 

While it is true that industrial grade mineral oil contains carcinogenic components (so-called polycyclic compounds), these are completely removed from cosmetic and food grade mineral oil and there is no scientific data showing that the pure, cosmetic grade version is carcinogenic.

What is more, in terms of the general health effects of mineral oils used in cosmetics, a 2017 study reviewed the data on their skin penetration and concluded that "the cosmetic use of mineral oils and waxes does not present a risk to consumers due to a lack of systemic exposure."  

Another super common myth surrounding mineral oil is that it is comedogenic. A 2005 study titled "Is mineral oil comedogenic?" examined this very question and guess what happened? The study concluded that  "based on the animal and human data reported, along with the AAD recommendation, it would appear reasonable to conclude that mineral oil is noncomedogenic in humans.

Overall, we feel that the scaremongering around mineral oil is not justified. For dry and super-sensitive skin types it is a great option. However, if you do not like its origin or its heavy feeling or anything else about it, avoiding it has never been easier. Mineral oil has such a bad reputation nowadays that cosmetic companies hardly dare to use it anymore. 

What-it-does: emollient

A modified dimethicone-type silicone molecule that also contains amino-groups. Having amino-groups means that Amodimethicone also has Nitrogen in its molecule that likes to have a positive charge. Positively charged (or quaternised) molecules are substantive to skin and hair as those are negatively charged surfaces and are excellent film formers. Amodiemthcone is no exception and it is especially recommended for hair-care products for its long-lasting hair conditioning benefits.

What-it-does: emulsifying, surfactant/cleansing | Irritancy: 0 | Comedogenicity: 0

It's a common little helper ingredient that helps water and oil to mix together. Also, it can help to increase the solubility of some other ingredients in the formula. 

What-it-does: surfactant/cleansing

We don't have description for this ingredient yet.

What-it-does: emollient, viscosity controlling, emulsion stabilising, emulsifying, surfactant/cleansing | Irritancy: 2 | Comedogenicity: 2

A handy multi-tasker, white to light yellowish oil-loving wax that works very well in oil-in-water emulsions.  It makes your skin feel nice and smooth (emollient),  stabilizes oil-water mixes and gives body to them.

Oh, and one more thing: it's a so-called fatty alcohol - the good, emollient type of alcohol that is non-drying and non-irritating. It is often mixed with fellow fatty alcohol, Cetyl Alcohol, and the mixture is called Cetearyl Alcohol in the ingredient list. 

We don't have description for this ingredient yet.

What-it-does: preservative

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

It's a little helper ingredient coming from corn, rice or potato starch that can help to keep skin mat (absorbent), to stabilise emulsions, and to keep the product together (binding). 

What-it-does: moisturizer/humectant, solvent, viscosity controlling | Irritancy: 0 | Comedogenicity: 0
  • It's a helper ingredient that improves the freeze-thaw stability of products
  • It's also a solvent, humectant and to some extent a penetration enhancer
  • It has a bad reputation among natural cosmetics advocates but cosmetic scientists and toxicology experts do not agree (read more in the geeky details section)
Read all the geeky details about Propylene Glycol here >>

Also-called: Candelilla Wax;Candelilla Cera | What-it-does: emollient | Irritancy: 0 | Comedogenicity: 1

A vegetable wax coming from the leaves of the North Mexican candelilla shrubs (Euphorbia cerifera and Euphorbia antisyphilitica).  Similar to other waxes, it is used to stabilize products and give body to them, or to keep stick type formulas solid. It has a melting point around 70C and has high gloss making it a good choice for lip products.

What-it-does: surfactant/cleansing

We don't have description for this ingredient yet.

Also-called: Zemea | What-it-does: solvent, moisturizer/humectant

Propanediol is a natural alternative for the often used and often bad-mouthed propylene glycol. It's produced sustainably from corn sugar and it's Ecocert approved. 

It's quite a multi-tasker: can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula. 

We don't have description for this ingredient yet.

What-it-does: solvent, viscosity controlling, perfuming | Irritancy: 0 | Comedogenicity: 0

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

What-it-does: viscosity controlling

A big polymer molecule that has a bunch of different versions and thus different uses. It can act as a film former,  as thickening agent, or it can increase the water-resistance in sunscreens. It is also used to entrap pigments/inorganic sunscreens within a micron size matrix for even coverage and easy application.

What-it-does: emulsifying | Irritancy: 0 | Comedogenicity: 3

A mainly oil-loving, vegetable raw material based ingredient that helps water and oil to mix together, aka emulsifier. It can also function as a wetting and dispersing agent helping insoluble particles such as color pigments or inorganic sunscreens (zinc/titanium dioxide) to disperse nice and even in liquids.  

Chemically speaking, it comes from the attachment of sorbitan (a dehydrated sorbitol (sugar) molecule) with the unsaturated fatty acid Oleic Acid, that creates a partly water (the sorbitan part) and partly oil soluble (oleic part) molecule. 

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

Also-called: Green Tea | What-it-does: antioxidant, soothing
  • Green tea is one of the most researched natural ingredients
  • The active parts are called polyphenols, or more precisely catechins (EGCG being the most abundant and most active catechin)
  • There can be huge quality differences between green tea extracts. The good ones contain 50-90% catechins (and often make the product brown and give it a distinctive smell)
  • Green tea is proven to be a great antioxidant, UV protectant, anti-inflammatory, anticarcinogenic and antimicrobial
  • Because of these awesome properties green tea is a great choice for anti-aging and also for skin diseases including rosacea, acne and atopic dermatitis
Read all the geeky details about Camellia Sinensis Leaf Extract here >>

It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little xanthan gum will make it more gel-like. Used alone, it can make the formula sticky and it is a good team player so it is usually combined with other thickeners and so-called rheology modifiers (helper ingredients that adjust the flow and thus the feel of the formula). The typical use level of Xantha Gum is below 1%, it is usually in the 0.1-0.5% range. 

Btw, Xanthan gum is all natural, a chain of sugar molecules (polysaccharide) produced from individual sugar molecules (glucose and sucrose) via fermentation. It’s approved by Ecocert and also used in the food industry (E415). 

Tocopherol - goodie
Also-called: Vitamin E | What-it-does: antioxidant | Irritancy: 0-3 | Comedogenicity: 0-3
  • Primary fat-soluble antioxidant in our skin
  • Significant photoprotection against UVB rays
  • Vit C + Vit E work in synergy and provide great photoprotection
  • Has emollient properties
  • Easy to formulate, stable and relatively inexpensive
Read all the geeky details about Tocopherol here >>

Also-called: Butylated Hydroxy Toluene | What-it-does: antioxidant, preservative

It's the acronym for Butylated Hydroxy Toluene. It's a common synthetic antioxidant that's used as a preservative.

There is some controversy around BHT. It's not a new ingredient, it has been used both as a food and cosmetics additive since the 1970s. Plenty of studies tried to examine if it's a carcinogen or not. This Truth in Aging article details the situation and also writes that all these studies examine BHT when taken orally.

As for cosmetics, the CIR (Cosmetic Ingredient Review) concluded that the amount of BHT used in cosmetic products is low (usually around 0.01-0.1%),  it does not penetrate skin far enough to be absorbed into the bloodstream and it is safe to use in cosmetics.

What-it-does: chelating, buffering

A little helper ingredient that is used to adjust the pH of the product. It also helps to keep products stay nice longer by neutralizing the metal ions in the formula (they usually come from water). 

Also-called: Fragrance, Parfum | What-it-does: perfuming

Exactly what it sounds: nice smelling stuff put into cosmetic products so that the end product also smells nice. Fragrance in the US and parfum in the EU is a generic term on the ingredient list that is made up of 30 to 50 chemicals on average (but it can have as much as 200 components!). 

If you are someone who likes to know what you put on your face then fragrance is not your best friend - there's no way to know what’s really in it.  

Also, if your skin is sensitive, fragrance is again not your best friend. It’s the number one cause of contact allergy to cosmetics. It’s definitely a smart thing to avoid with sensitive skin (and fragrance of any type - natural is just as allergic as synthetic, if not worse!). 

You may also want to take a look at...

what‑it‑does solvent
Normal (well kind of - it's purified and deionized) water. Usually the main solvent in cosmetic products. [more]
what‑it‑does viscosity controlling
A cationic polymer molecule (a big molecule with repeated subunits and a positive charge) that acts both as a film-former and conditioning ingredient as well as a thickening agent.  [more]
what‑it‑does emollient | solvent
irritancy, com. 0, 0-2
A clear, oily liquid that comes from refining crude oil. Even though it is a highly controversial ingredient, the scientific consensus is that it is a safe, non-irritating and effective emollient and moisturizer working mainly by occlusivity. [more]
what‑it‑does emollient
A modified dimethicone-type silicone molecule that also contains amino-groups. Having amino-groups means that Amodimethicone also has Nitrogen in its molecule that likes to have a positive charge. [more]
what‑it‑does emulsifying | surfactant/cleansing
irritancy, com. 0, 0
It's a common little helper ingredient that helps water and oil to mix together. Also, it can help to increase the solubility of some other ingredients in the formula. 
what‑it‑does surfactant/cleansing
what‑it‑does emollient | viscosity controlling | emulsifying | surfactant/cleansing
irritancy, com. 2, 2
A handy multi-tasker, white to light yellowish oil-loving wax that works very well in oil-in-water emulsions.  It makes your skin feel nice and smooth (emollient),  stabilizes oil-water mixes and gives body to them.Oh, and one more thing: [more]
what‑it‑does preservative
It's a little helper ingredient coming from corn, rice or potato starch that can help to keep skin mat (absorbent), to stabilise emulsions, and to keep the product together (binding). 
what‑it‑does moisturizer/humectant | solvent | viscosity controlling
irritancy, com. 0, 0
A common glycol that improves the freeze-thaw stability of products. It's also a solvent, humectant and to some extent a penetration enhancer. [more]
what‑it‑does emollient
irritancy, com. 0, 1
A vegetable wax coming from the leaves of the North Mexican candelilla shrubs. It is used to stabilize products and give body to them, or to keep stick type formulas solid. [more]
what‑it‑does surfactant/cleansing
what‑it‑does solvent | moisturizer/humectant
A natural corn sugar derived glycol. It can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula. [more]
what‑it‑does antimicrobial/antibacterial | preservative
what‑it‑does solvent | viscosity controlling | perfuming
irritancy, com. 0, 0
what‑it‑does emulsifying | surfactant/cleansing
what‑it‑does viscosity controlling
A big polymer molecule that has a bunch of different versions and thus different uses. It can act as a film former,  as a thickening agent, or it can increase the water-resistance in sunscreens. [more]
what‑it‑does emulsifying
irritancy, com. 0, 3
A mainly oil-loving, vegetable raw material based ingredient that helps water and oil to mix together, aka emulsifier. It can also function as a wetting and dispersing agent helping insoluble particles such as color pigments or inorganic sunscreens (zinc/titanium dioxide) to disperse nice and even in liquids.   [more]
what‑it‑does antimicrobial/antibacterial | emulsifying | preservative | surfactant/cleansing
what‑it‑does antioxidant | soothing
Green Tea - one of the most researched natural ingredients that contains the superstar actives called catechins. It has proven antioxidant, anti-inflammatory, antimicrobial and anticarcinogenic properties. [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does antioxidant
irritancy, com. 0-3, 0-3
Pure Vitamin E. Great antioxidant that gives significant photoprotection against UVB rays. Works in synergy with Vitamin C. [more]
what‑it‑does antioxidant | preservative
It's the acronym for Butylated Hydroxy Toluene. It's a common synthetic antioxidant that's used as a preservative.There is some controversy around BHT. [more]
what‑it‑does chelating | buffering
A helper ingredient that is used to adjust the pH of the product. Also helps to keep products stay nice longer by neutralizing the metal ions in the formula. 
what‑it‑does perfuming
The generic term for nice smelling stuff put into cosmetic products so that the end product also smells nice. It is made up of 30 to 50 chemicals on average. [more]