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Kiehl’s Nightly Refining Micro-Peel Concentrate

Nightly Refining Micro-Peel Concentrate

A concentrated facial peel that helps to accelerate surface skin cell turnover for fresh, radiant skin.
Uploaded by: gibsonstone on

Kiehl’s Nightly Refining Micro-Peel Concentrate
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. 

  • It's a super common and super debated skincare ingredient
  • It has several benefits: great solvent, penetration enhancer, creates cosmetically elegant, light formulas, great astringent and antimicrobial
  • It can be very drying if it's in the first few ingredients on an ingredient list
  • Some experts even think that regular exposure to alcohol damages skin barrier and causes inflammation though it's a debated opinion (read more in geeky details tab)
Read all the geeky details about Alcohol Denat. here >>

What-it-does: buffering

We don't have description for this ingredient yet.

What-it-does: moisturizer/humectant

A derivative of Urea, that works as a strong moisturizer and humectant meaning that it helps the skin to cling onto water and thus to make it hydrated and elastic.

According to manufacturer's data,  Hydroxyethyl Urea has a similar moisturizing ability to glycerin (measured at 5%), but it feels nicer on the skin as it is non-sticky and non-tacky and gives a lubricous and moist feeling to the skin.

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: Bilberry Fruit Extract

We don't have description for this ingredient yet.

Also-called: lye | What-it-does: buffering

The unfancy name for it is lye. It’s a solid white stuff that’s very alkaline and used in small amounts to adjust the pH of the product and make it just right. 

For example, in case of AHA or BHA exfoliants, the right pH is super-duper important, and pH adjusters like sodium hydroxide are needed.  

BTW, lye is not something new. It was already used by ancient Egyptians to help oil and fat magically turn into something else. Can you guess what? Yes, it’s soap. It still often shows up in the ingredient list of soaps and other cleansers.

Sodium hydroxide in itself is a potent skin irritant, but once it's reacted (as it is usually in skin care products, like exfoliants) it is totally harmless.

We don't have description for this ingredient yet.

Also-called: Sugar Cane Extract;Saccharum Officinarum Extract | What-it-does: moisturizer/humectant

Also known as Sugarcane, Saccharum Officinarum is a handy moisturizing ingredient mostly used as a humectant. This means that it can help the skin to attract water and then to hold onto it. 
 
It bears a close relationship to AHA superstar, Glycolic Acid that can be derived from it, so it's often claimed that Sugarcane Extract itself also exfoliates and brightens the skin. We could not find any research studies to back this up, but Saccharum Officinarum very often comes to the formula combined with other acid containing plant extracts trade named ACB Fruit Mix. According to manufacturer data, 5% of the fruit mix increases cellular renewal by 24%, while 4% pure Glycolic did the same by 33%. So maybe, a tiny bit of exfoliation, but if you want proven efficacy, stick to pure acids. 

Glycerin - superstar
Also-called: Glycerol | What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0
  • A natural moisturizer that’s also in our skin
  • A super common, safe, effective and cheap molecule used for more than 50 years
  • Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
  • Effective from as low as 3% with even more benefits at higher concentrations up to 20-40% (around 10% is a good usability-effectiveness sweet spot)
  • High-glycerin moisturizers are awesome for treating severely dry skin
Read all the geeky details about Glycerin here >>

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. 

What-it-does: chelating

Though its name says acid, it's not really an exfoliant. It's a plant extract with some antioxidant properties. Its main thing in cosmetic products is to neutralize the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.  It's a natural alternative to sometimes bad-mouthed chelating agents, EDTAs.

What-it-does: viscosity controlling

A natural polysaccharide (big sugar molecule) coming from red edible seaweeds. It is used as a helper ingredient for its gelling, thickening and stabilizing properties.  

What-it-does: preservative

It’s pretty much the current IT-preservative. It’s safe and gentle, but even more importantly, it’s not a feared-by-everyone-mostly-without-scientific-reason paraben.

It’s not something new: it was introduced around 1950 and today it can be used up to 1% worldwide. It can be found in nature - in green tea - but the version used in cosmetics is synthetic. 

Other than having a good safety profile and being quite gentle to the skin it has some other advantages too. It can be used in many types of formulations as it has great thermal stability (can be heated up to 85°C) and works on a wide range of pH levels (ph 3-10). 

It’s often used together with ethylhexylglycerin as it nicely improves the preservative activity of phenoxyethanol.

We don't have description for this ingredient yet.

Also-called: Lemon Fruit Extract;Citrus Limon Fruit Extract

If life gives the cosmetic industry lemon, it makes lemon fruit extract.  As to why, we can write here extremely similar things to our shiny description of orange fruit extract.  Being both of them citruses, they contain very similar active compounds with very similar (potential) effects on the skin. 

Just like orange fruit, lemon fruit also contains citric acid so it is commonly used as a natural, mild exfoliating agent. If this is the case, it is usually combined with other AHA containing fruit extracts such as bilberrysugar cane, orange, and sugar maple in a super popular ingredient mix trade named ACB Fruit Mix.

But, citrus fruits are chemically complex mixtures with a bunch of other active components such as vitamin C, flavonoids, phenolics, carbohydrates and essential oil (this latter one coming from the rind of the fruit, but still present in some amount in the fruit extract). These have the potential to give lemon extract antioxidant, antibacterial, anti-dandruff, venotonic and moisturizing properties, but the essential oil also brings some questionable compounds such as fragrance allergen limonene or phototoxic compound bergaptene. If your skin is sensitive, be careful with citrus extracts. 

Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.

It is typically used in tiny amounts, around 0.1% or less.

Also-called: Sugar Maple Extract;Acer Saccharum Extract

The extract coming from the Sugar Maple tree, the one whose leaf is on the Canadian flag and gives us maple syrup.

The main reason it is used in skin care is that it contains natural AHA acids, namely Malic and Tartaric, and hence why it supposedly helps slough off dead skin cells in combination with other acid-containing fruit extracts as part of the trade name ACB Fruit Mix. The manufacturer claims that both malic and tartaric increase elasticity in the skin, but from our research, the only confirmed uses of these acids are as pH adjusters, especially in the tiny amounts they can be found in the Fruit Mix (less than 1%).  

What-it-does: abrasive/scrub

We don't have description for this ingredient yet.

What-it-does: preservative

It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It’s not a strong one and doesn’t really work against bacteria, but more against mold and yeast. To do that it has to break down to its active form, sorbic acid. For that to happen, there has to be water in the product and the right pH value (pH 3-4). 

But even if everything is right, it’s not enough on its own. If you see potassium sorbate you should see some other preservative next to it too.

BTW, it’s also a food preservative and even has an E number, E202.

A spray-dried or freeze-dried version of Aloe Leaf Juice. The point of both drying methods is to make water evaporate from the juice and leave just the "useful" components behind.

So the aloe powder has similar soothing, emollient and moisturizing properties as the juice. You can read a bit more about the juice here. 

Adenosine - goodie

Adenosine is an important little compound in our body that has a vital cell-signalling role. Research on smearing it on our face is also promising and shows so far a couple of things:

  • It can help with wound healing
  • It’s a good anti-inflammatory agent
  • It might even help with skin’s own collagen production and improve skin firmness and elasticity
  • It helps with barrier repair and protection
  • It might be even useful for the hair helping with hair thickness and hair growth
What-it-does: preservative, deodorant

If you have spotted ethylhexylglycerin on the ingredient list, most probably you will see there also the current IT-preservative, phenoxyethanol. They are good friends because ethylhexylglycerin can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too.

Also, it's an effective deodorant and a medium spreading emollient

We don't have description for this ingredient yet.

What-it-does: preservative

A helper ingredient that helps to make the products stay nice longer, aka preservative. It works mainly against fungi. 

It’s pH dependent and works best at acidic pH levels (3-5). It’s not strong enough to be used in itself so it’s always combined with something else, often with potassium sorbate.

Also-called: Form of Vitamin C | What-it-does: antioxidant, skin brightening

A form of skincare superstar, vitamin C. If you do not know why vitamin C is such a big deal in skincare, we have a really detailed, geeky description that's good to read. :) 

So now you know that because pure vitamin C is such a diva (very unstable and hard to formulate) the cosmetic industry is trying to come up with some derivatives that have the badass anti-aging properties of vitamin C (antioxidant protection + collagen boosting + fading hyperpigmentation) but without the disadvantages. This is a hard task, and there is not yet a derivative that is really proven to be better in every aspect, but Ascorbyl Glucoside is one of the best options when it comes to vitamin C derivatives. Let's see why:

First, it's really stable and easy to formulate, so the problems that come with pure vitamin C are solved here.

Second, in vitro (meaning made in the lab, not on real humans) studies show that ascorbyl glucoside can penetrate the skin. This is kind of important for an anti-aging ingredient to do the job, so this is good news, though in-vivo (made on real humans) studies are still needed. 

Third, in-vitro studies show that after ascorbyl glucoside is absorbed into the skin it is converted to pure vitamin C (though the rate of conversion is still a question mark). It also shows all the three anti-aging benefits (antioxidant protection + collagen boosting + fading hyperpigmentation) that pure vitamin C does

Bottom line: ascorbyl glucoside is one of the best and most promising vitamin C derivatives that shows similar benefits to that of pure vitamin C, but it's less proven (in vivo vs. in vitro studies) and the extent of the benefits are also not the same.  

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 antimicrobial/antibacterial | solvent | viscosity controlling
Alcohol with some additives to make it unconsumable. It is great solvent, penetration enhancer, creates cosmetically elegant, light formulas, great astringent, and antimicrobial. In large amounts, it can be very drying to the skin. [more]
what‑it‑does buffering
what‑it‑does moisturizer/humectant
A derivative of Urea, that works as a strong moisturizer and humectant meaning that it helps the skin to cling onto water and thus to make it hydrated and elastic. According to manufacturer's data,  Hydroxyethyl Urea has a similar moisturizing ability to glycerin (measured at 5%), but it feels nicer on the skin as it is non-sticky and non-tacky and gives a lubri [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 buffering
Lye - A solid white stuff that’s very alkaline and used in small amount to adjust the pH of the product.  [more]
what‑it‑does moisturizer/humectant
Also known as Sugarcane, Saccharum Officinarum is a handy moisturizing ingredient mostly used as a humectant. This means that it can help the skin to attract water and then to hold onto it.  It bears a close relationship to AHA superstar, Glycolic Acid that can be derived from it, so it's often claimed that Sugarcane  [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
A real oldie but a goodie. Great natural moisturizer and skin-identical ingredient that plays an important role in skin hydration and general skin health. [more]
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 chelating
Though its name says acid, it's not really an exfoliant. It's a plant extract with some antioxidant properties. Its main thing in cosmetic products is to neutralize the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes. [more]
what‑it‑does viscosity controlling
A natural polysaccharide (big sugar molecule) coming from red edible seaweeds. It is used as a helper ingredient for its gelling, thickening and stabilizing properties. [more]
what‑it‑does preservative
Pretty much the current IT-preservative. It’s safe and gentle, and can be used up to 1% worldwide. [more]
If life gives the cosmetic industry lemon, it makes lemon fruit extract.  As to why, we can write here extremely similar things to our shiny description of orange fruit extract.  Being both of them citruses, they contain very similar active compounds with very similar (potential) effects on the skin.  [more]
what‑it‑does chelating | viscosity controlling
Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes. [more]
The extract coming from the Sugar Maple tree, the one whose leaf is on the Canadian flag and gives us maple syrup.The main reason it is used in skin care is that it contains natural AHA acids, namely Malic and Tartaric, and hence why it supposedly helps slough off dead skin cells in combination with other acid-containing fruit extracts as part of the trade name ACB Fruit Mix. [more]
what‑it‑does abrasive/scrub
what‑it‑does preservative
A not so strong preservative that doesn’t really work against bacteria, but more against mold and yeast. [more]
what‑it‑does soothing | moisturizer/humectant
A spray-dried or freeze-dried version of Aloe Leaf Juice. Has similar soothing, emollient and moisturizing properties as the juice itself. [more]
what‑it‑does cell-communicating ingredient
An important compound in our body that has a vital cell-signalling role. It is wound healing, anti-inflammatory and can help with barrier repair. [more]
what‑it‑does preservative
It can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too. [more]
what‑it‑does preservative
A preservative that works mainly against fungi. Has to be combined with other preservatives. [more]
what‑it‑does antioxidant | skin brightening
A stable and easy to formulate form of skincare superstar, vitamin C. In-vitro studies show that it shows all the three anti-aging benefits (antioxidant protection + collagen boosting + fading hyperpigmentation) that pure vitamin C does. [more]