Follow us on our new Insta page »
Kate Somerville Deep Tissue Repair

Kate Somerville
Deep Tissue Repair

A high-performance, age-defense moisturizer with an exclusive blend of Peptides designed to provide intense hydration.
Uploaded by: roxanacoada on 24/11/2018

Skim through

Ingredient name what-it-does irr., com. ID-Rating
Water/Aqua/Eau solvent
Stearic Acid emollient, viscosity controlling 0, 2-3
Cetearyl Alcohol emollient, viscosity controlling 1, 2
Ceteareth-20 emulsifying, surfactant/​cleansing 3, 2
Glycerin skin-identical ingredient, moisturizer/​humectant 0, 0 superstar
Isopropyl Myristate emollient 3, 3-5
Isocetyl Stearoyl Stearate emollient
Dimethicone emollient 0, 1
Cyclopentasiloxane emollient, solvent
C12-15 Alkyl Benzoate emollient, antimicrobial/​antibacterial
Caprylic/Capric Triglyceride emollient
Orbignya Oleifera Seed Oil emollient 0, 1
Cannabis Sativa Seed Oil emollient
Squalane skin-identical ingredient, emollient 0, 1 goodie
Cholesterol skin-identical ingredient, emollient 0, 0 goodie
Urea skin-identical ingredient, moisturizer/​humectant goodie
Sodium Pca skin-identical ingredient, moisturizer/​humectant 0, 0 goodie
Cetearyl Alcohol emollient, viscosity controlling 1, 2
Macadamia Ternifolia Seed Oil emollient goodie
Simmondsia Chinensis (Jojoba) Seed Oil emollient 0, 0-2 goodie
Silk Powder
Tribehenin emollient
Triethanolamine buffering 0, 2
Xanthan Gum viscosity controlling
Butylene Glycol moisturizer/​humectant, solvent 0, 1
Tocopheryl Acetate antioxidant 0, 0
Allantoin soothing 0, 0 goodie
Trehalose moisturizer/​humectant goodie
Citrus Grandis (Grapefruit) Peel Oil perfuming icky
Ascorbyl Palmitate antioxidant 0, 2 icky
Ceramide 2
Peg-10 Rapeseed Sterol surfactant/​cleansing, emulsifying, surfactant/​cleansing
Triacetin antimicrobial/​antibacterial, solvent 0, 0
Copper Pca moisturizer/​humectant
Polyquaternium-51 moisturizer/​humectant
Sodium Hyaluronate skin-identical ingredient, moisturizer/​humectant 0, 0 goodie
Palmitoyl Oligopeptide cell-communicating ingredient goodie
Disodium Edta chelating
Citric Acid exfoliant, buffering goodie
Sodium Benzoate preservative
Potassium Sorbate preservative
Chlorphenesin preservative, antimicrobial/​antibacterial
Fragrance (Parfum) perfuming icky
Hexyl Cinnamal perfuming icky
Butylphenyl Methylpropional perfuming icky
Limonene perfuming, solvent icky

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. 

Expand to read more

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: emollient, viscosity controlling | Irritancy: 0 | Comedogenicity: 2-3

A common multi-tasker fatty acid. It makes your skin feel nice and smooth (emollient), gives body to cream type products and helps to stabilize water and oil mixes (aka emulsions).

What-it-does: emollient, viscosity controlling | Irritancy: 1 | Comedogenicity: 2

An extremely common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams and lotions. It also helps to stabilize oil-water mixes (emulsions), though it does not function as an emulsifier in itself. Its typical use level in most cream type formulas is 2-3%.  

It’s a so-called fatty alcohol, a mix of cetyl and stearyl alcohol, other two emollient fatty alcohols.  Though chemically speaking, it is alcohol (as in, it has an -OH group in its molecule), its properties are totally different from the properties of low molecular weight or drying alcohols such as denat. alcohol. Fatty alcohols have a long oil-soluble (and thus emollient) tail part that makes them absolutely non-drying and non-irritating and are totally ok for the skin.

What-it-does: emulsifying, surfactant/cleansing | Irritancy: 3 | Comedogenicity: 2

A common functional ingredient that helps to keep the oil-loving and water-loving ingredients together (emulsifier), stabilizes and thickens the products. 

Chemically speaking, it is ethoxylated Cetearyl alcohol, meaning that some ethylene oxide is added to the fatty alcohol to increase the water-soluble part in the molecule. The result is that the mainly oil soluble, emollient fatty alcohol is converted to an emulsifier molecule that keeps oil and water mixed in creams. The number in the name of Ceteareth emulsifiers refers to the average number of ethylene oxide molecules added and 20 makes a good emulsifier.

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 >>

What-it-does: emollient | Irritancy: 3 | Comedogenicity: 3-5

A  clear, colorless oil-like liquid that makes the skin feel smooth and nice (aka emollient) and it does so without it being greasy.

What's more, it can even reduce the heavy, greasy feel in products with high oil content. It's also fast-spreading meaning that it gives the formula a good, nice slip. It absorbs quickly into the skin and helps other ingredients to penetrate quicker and deeper. 

Expand to read more

Thanks to all this, it's one of the most commonly used emollients out there. There is just one little drawback: it has a high comedogenic index (5 out of 5...), so it might clog pores if you're prone to it. 

What-it-does: emollient

An emollient ester giving a long-lasting lubricious skin feel. 

What-it-does: emollient | Irritancy: 0 | Comedogenicity: 1

Probably the cheapest and most common silicone of all. It is a polymer (created from repeating subunits) molecule and has different molecular weight and thus different viscosity versions from water-light to thick liquid.

As for skincare, it makes the skin silky smooth, creates a subtle gloss and forms a protective barrier (aka occlusive). Also, works well to fill in fine lines and wrinkles and give skin a plump look (of course that is only temporary, but still, it's nice). There are also scar treatment gels out there using dimethicone as their base ingredient. It helps to soften scars and increase their elasticity. 

Expand to read more

As for hair care, it is a non-volatile silicone meaning that it stays on the hair rather than evaporates from it and smoothes the hair like no other thing. Depending on your hair type, it can be a bit difficult to wash out and might cause some build-up (btw, this is not true to all silicones, only the non-volatile types). 

What-it-does: emollient, solvent

A super commonly used 5 unit long, cyclic structured silicone that is water-thin and does not stay on the skin but evaporates from it (called volatile silicone). Similar to other silicones, it gives skin and hair a silky, smooth feel

It's often combined with the non-volatile (aka stays on the skin) dimethicone as the two together form a water-resistant, breathable protective barrier on the skin without a negative tacky feel.

An often used emollient with a light and silky feel. It's very mild to both skin and eyes and spreads nicely and easily. It's often used in sunscreens as it's also an excellent solvent for sunscreen agents. 

What-it-does: emollient

A super common emollient that makes your skin feel nice and smooth. It comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. It’s a nice ingredient that just feels good on the skin, and it’s also easy to formulate with. No wonder it’s popular. 

Also-called: Babassu Oil | What-it-does: emollient | Irritancy: 0 | Comedogenicity: 1

We don't have description for this ingredient yet.

Also-called: Hemp Oil | What-it-does: emollient

We don't have description for this ingredient yet.

Squalane - goodie
What-it-does: skin-identical ingredient, emollient | Irritancy: 0 | Comedogenicity: 1

It seems to us that squalane is in fashion and there is a reason for it. Chemically speaking, it is a saturated  (no double bonds) hydrocarbon (a molecule consisting only of carbon and hydrogen), meaning that it's a nice and stable oily liquid with a long shelf life. 

It occurs naturally in certain fish and plant oils (e.g. olive), and in the sebum (the oily stuff our skin produces) of the human skin. As f.c. puts it in his awesome blog post, squalane's main things are "emolliency, surface occlusion, and TEWL prevention all with extreme cosmetic elegance". In other words, it's a superb moisturizer that makes your skin nice and smooth, without being heavy or greasy.

Expand to read more

Another advantage of squalane is that it is pretty much compatible with all skin types and skin conditions. It is excellent for acne-prone skin and safe to use even if you have fungi-related skin issues, like seborrhea or fungal acne.

The unsaturated (with double bonds) and hence less stable version of Squalane is Squalene, you can read about it here >> 

Cholesterol - goodie
What-it-does: skin-identical ingredient, emollient | Irritancy: 0 | Comedogenicity: 0

It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. Together with ceramides and fatty acids, they play a vital role in having a healthy skin barrier and keeping the skin hydrated. 

Apart from being an important skin-identical ingredient, it's also an emollient and stabilizer

Urea - goodie
Also-called: Carbamide | What-it-does: skin-identical ingredient, moisturizer/humectant

Yes, it's the thing that can be found naturally in pee. And in the skin. It is an awesome natural moisturizing factor, aka NMF.  NMFs are important components that help the skin to hold onto water and keep it plump, elastic and hydrated. Urea makes up about 7% of NMFs next to other things such as amino acids (40%), PCA (12%) or Lactate (12%).

What makes urea special, is that it is not only a simple moisturizer, but it is thought to be a "small-molecule regulator of epidermal structure and function" meaning that it has a bunch of extra biological activities. It acts as a mild keratolytic agent (some of its moisturizing action is thought to come from urea's ability to break down bonds in the protein called filaggrin and thus freeing up amino acids in the skin), enhances antimicrobial peptide expression and improves skin barrier function

Expand to read more

Being a mild keratolytic agent and strong moisturizer means that high-percentage (10-40%) urea treatments are found effective in a bunch of skin disorders connected to excessive dryness and malfunctioning skin barrier such as ichthyosis, xerosis, psoriasis, eczema and seborrheic dermatitis.  

Overall, just like glycerin, urea is a real oldie but a goodie, a nice ingredient in any moisturizer.

Sodium Pca - goodie
What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0

PCA stands for Pyrrolidone Carboxylic Acid and though it might not sound like it, it is a thing that can be found naturally in our skin. The sodium salt form of PCA is an important skin-identical ingredient and great natural moisturizer that helps the skin to hold onto water and stay nicely hydrated. 

What-it-does: emollient, viscosity controlling | Irritancy: 1 | Comedogenicity: 2

An extremely common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams and lotions. It also helps to stabilize oil-water mixes (emulsions), though it does not function as an emulsifier in itself. Its typical use level in most cream type formulas is 2-3%.  

It’s a so-called fatty alcohol, a mix of cetyl and stearyl alcohol, other two emollient fatty alcohols.  Though chemically speaking, it is alcohol (as in, it has an -OH group in its molecule), its properties are totally different from the properties of low molecular weight or drying alcohols such as denat. alcohol. Fatty alcohols have a long oil-soluble (and thus emollient) tail part that makes them absolutely non-drying and non-irritating and are totally ok for the skin.

Also-called: Macadamia Oil | What-it-does: emollient

The golden yellow oil coming from the Macadamia nut, a native Australian nut. Similar to other plant oils, it's loaded with emollient and nourishing fatty acids. It's a high oleic acid oil (50-67% oleic acid and only 0-5% linoleic acid) that makes it very emollient and ideal for dry skin types (and less ideal for acne-prone skin).

Its unique property is that it contains high amounts of a rare fatty acid called palmitoleic acid (12-25%) that give Macadamia oil a "cushiony" feel. It's also easily absorbed and makes the skin soft and supple. 

Also-called: Jojoba Oil | What-it-does: emollient | Irritancy: 0 | Comedogenicity: 0-2

Jojoba is a drought resistant evergreen shrub native to South-western North America. It's known and grown for jojoba oil, the golden yellow liquid coming from the seeds (about 50% of the weight of the seeds will be oil).  

At first glance, it seems like your average emollient plant oil: it looks like an oil and it's nourishing and moisturizing to the skin but if we dig a bit deeper, it turns out that jojoba oil is really special and unique: technically - or rather chemically - it's not an oil but a wax ester (and calling it an oil is kind of sloppy). 

Expand to read more

So what the heck is a wax ester and why is that important anyway? Well, to understand what a wax ester is, you first have to know that oils are chemically triglycerides: one glycerin + three fatty acids attached to it. The fatty acids attached to the glycerin vary and thus we have many kinds of oils, but they are all triglycerides. Mother Nature created triglycerides to be easily hydrolyzed (be broken down to a glycerin + 3 fatty acid molecules) and oxidized (the fatty acid is broken down into small parts) - this happens basically when we eat fats or oils and our body generates energy from it.

Mother Nature also created wax esters but for a totally different purpose. Chemically, a wax ester is a fatty acid + a fatty alcohol, one long molecule. Wax esters are on the outer surface of several plant leaves to give them environmental protection. 25-30% of human sebum is also wax esters to give us people environmental protection. 

So being a wax ester results in a couple of unique properties: First, jojoba oil is extremely stable. Like crazy stable. Even if you heat it to 370 C (698 F) for 96 hours, it does not budge. (Many plant oils tend to go off pretty quickly). If you have some pure jojoba oil at home, you should be fine using it for years. 

Second, jojoba oil is the most similar to human sebum (both being wax esters), and the two are completely miscible. Acne.org has this not fully proven theory that thanks to this, jojoba might be able to "trick" the skin into thinking it has already produced enough sebum, so it might have "skin balancing" properties for oily skin.

Third, jojoba oil moisturizes the skin through a unique dual action: on the one hand, it mixes with sebum and forms a thin, non-greasy, semi-occlusive layer; on the other hand, it absorbs into the skin through pores and hair follicles then diffuses into the intercellular spaces of the outer layer of the skin to make it soft and supple.

On balance, the point is this: in contrast to real plant oils, wax esters were designed by Mother Nature to stay on the surface and form a protective, moisturizing barrier and jojoba oil being a wax ester is uniquely excellent at doing that.

We don't have description for this ingredient yet.

What-it-does: emollient

It's the triglyceride of behenic acid that works as a thickening or gelling agent, as a compacting agent for pressed powders, and improves heat stability of emulsions. 

What-it-does: buffering | Irritancy: 0 | Comedogenicity: 2

It’s a little helper ingredient that helps to set the pH of a cosmetic formulation to be just right. It’s very alkaline (you know the opposite of being very acidic): a 1% solution has a pH of around 10.

It does not have the very best safety reputation but in general, you do not have to worry about it. 

Expand to read more

What is true is that if a product contains so-called N-nitrogenating agents (e.g.: preservatives like 2-Bromo-2-Nitropropane-1,3-Diol, 5-Bromo-5-Nitro- 1,3-Dioxane or sodium nitrate - so look out for things with nitro, nitra in the name) that together with TEA can form some not nice carcinogenic stuff (that is called nitrosamines). But with proper formulation that does not happen, TEA in itself is not a bad guy. 

But let’s assume a bad combination of ingredients were used and the nitrosamines formed. :( Even in that case you are probably fine because as far as we know it cannot penetrate the skin. 

But to be on the safe side, if you see Triethanolamine in an INCI and also something with nitra, nitro in the name of it just skip the product, that cannot hurt.

It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little of 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). 

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). 

What-it-does: moisturizer/humectant, solvent | Irritancy: 0 | Comedogenicity: 1

Butylene glycol, or let’s just call it BG, is a multi-tasking colorless, syrupy liquid. It’s a great pick for creating a nice feeling product.  

BG’s main job is usually to be a solvent for the other ingredients. Other tasks include helping the product to absorb faster and deeper into the skin (penetration enhancer), making the product spread nicely over the skin (slip agent), and attracting water (humectant) into the skin.

Expand to read more

It’s an ingredient whose safety hasn’t been questioned so far by anyone (at least not that we know about). BG is approved by Ecocert and is also used enthusiastically in natural products. BTW, it’s also a food additive. 

Also-called: Vitamin E Acetate | What-it-does: antioxidant | Irritancy: 0 | Comedogenicity: 0

It’s the most commonly used version of pure vitamin E in cosmetics. You can read all about the pure form here. This one is the so-called esterified version. 

According to famous dermatologist, Leslie Baumann while tocopheryl acetate is more stable and has a longer shelf life, it’s also more poorly absorbed by the skin and may not have the same awesome photoprotective effects as pure Vit E. 

Allantoin - goodie
What-it-does: soothing | Irritancy: 0 | Comedogenicity: 0

Super common soothing ingredient. It can be found naturally in the roots & leaves of the comfrey plant, but more often than not what's in the cosmetic products is produced synthetically. 

It's not only soothing but it' also skin-softening and protecting and can promote wound healing.

Trehalose - goodie
What-it-does: moisturizer/humectant

A type of sugar that has water-binding properties and helps to keep your skin hydrated

Also-called: Grapefruit Peel Oil | What-it-does: perfuming

The essential oil coming from the rind of the grapefruit. In general, the main component of citrus peel oils is limonene (86-95% for grapefruit peel), a super common fragrant ingredient that makes everything smell nice (but counts as a frequent skin sensitizer).

Other than that, citrus peel also contains the problematic compound called furanocoumarin that makes them mildly phototoxic. In general, the more sour-bitter the fruit, the more problematic it is regarding phototoxicity: orange and clementine peel contain less of it while lemon, grapefruit, and bergamot contain some more. Be careful with it if it is in a product for daytime use.  

Also-called: Form of Vitamin C | What-it-does: antioxidant | Irritancy: 0 | Comedogenicity: 2

A form of skincare superstar, vitamin C. Even though we are massive vitamin C fans,  Ascorbyl Palmitate  (AP) is our least favorite. (Btw, if you do not know what the big deal with vitamin C is then you are missing out. You must go and read our geeky details about it.) 

So, AP is one of the attempts by the cosmetics industry to solve the stability issues with vitamin C while preserving its benefits,  but it seems to fall short on several things.

Expand to read more

What's the problem?

Firstly, it's stability is only similar to that of pure ascorbic acid (AA), which means it is not really stable. A great study in the Journal of Cosmetic Dermatology compared a bunch of vitamin C derivatives and this derivative was the only one where the study said in terms of stability that it's "similar to AA". Not really that good.

Second, a study that examined the skin absorption of vitamin C found that ascorbyl palmitate did not increase the skin levels of AA. This does not mean that ascorbyl palmitate cannot penetrate the skin (because it can, it's oil soluble and the skin likes to absorb oil soluble things) but this means that it's questionable if ascorbyl palmitate can be converted into pure Vit C in the skin. Even if it can be converted, the palmitate part of the molecule is more than the half of it, so the efficacy will not be good and we have never seen a serum that contains a decent (and proudly disclosed) amount of AP.  We are highly skeptical what effect a tiny amount of AP has in a formula.

Third, another study that wanted to examine the antioxidant properties of AP was surprised to find that even though AP does have nice antioxidant properties; following UVB radiation (the same one that comes from the sun) it also promotes lipid peroxidation and cytotoxicity. It was only an in-vitro study meaning that it was done on cell cultures and not on real people, but still, this also does not support the use of AP too much. 

The only good thing we can write about Ascorbyl Palmitate is that there is an in-vitro (made in the lab, not on real people) study showing that it might be able to boost collagen production.

Regarding the skin-brightening properties of pure vitamin C, this is another magic property AP does not have, or at least there is no data, not even in-vitro, about it.

Overall, Ascorbyl Palmitate is our least favorite vitamin C derivative. It is there in lots of products in tiny amounts (honestly, we do not really understand why), however, we do not know about any vitamin C serum featuring AP in high amounts. That is probably no coincidence. If you are into vitamin C, you can take a look at more promising derivatives here

We don't have description for this ingredient yet.

We don't have description for this ingredient yet.

What-it-does: antimicrobial/antibacterial, solvent | Irritancy: 0 | Comedogenicity: 0

We don't have description for this ingredient yet.

What-it-does: moisturizer/humectant

We don't have description for this ingredient yet.

What-it-does: moisturizer/humectant

A biocompatible copolymer (a big molecule that consists of more than one type of building blocks) that has the same structure as important cell membrane ingredient, phospholipid. It's a good skin moisturizer, leaves a silky, smooth feel on the skin and can help to reduce irritation caused by some not-so-nice ingredients (like surfactants).

What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0

It’s the - sodium form - cousin of the famous NMFhyaluronic acid (HA). If HA does not tell you anything we have a super detailed, geeky explanation about it here.  The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to hold onto water, being plump and elastic. HA is famous for its crazy water holding capacity as it can bind up to 1000 times its own weight in water.

As far as skincare goes, sodium hyaluronate and hyaluronic acid are pretty much the same and the two names are used interchangeably. As cosmetic chemist kindofstephen writes on reddit  "sodium hyaluronate disassociates into hyaluronic acid molecule and a sodium atom in solution". 

Expand to read more

In spite of this, if you search for "hyaluronic acid vs sodium hyaluronate" you will find on multiple places that sodium hyaluronate is smaller and can penetrate the skin better. Chemically, this is definitely not true, as the two forms are almost the same, both are polymers and the subunits can be repeated in both forms as much as you like. (We also checked Prospector for sodium hyaluronate versions actually used in cosmetic products and found that the most common molecular weight was 1.5-1.8 million Da that absolutely counts as high molecular weight).

What seems to be a true difference, though, is that the salt form is more stable, easier to formulate and cheaper so it pops up more often on the ingredient lists. 

If you wanna become a real HA-and-the-skin expert you can read way more about the topic at hyaluronic acid (including penetration-questions, differences between high and low molecular weight versions and a bunch of references to scientific literature).

Also-called: Biopeptide El, pal-VGVAPG, Palmitoyl Oligopeptide (old name);Palmitoyl Hexapeptide-12 | What-it-does: cell-communicating ingredient

A six amino acid peptide that is claimed to improve firmness and skin tone. Its amino acid sequence is Val-Gly-Val-Ala-Pro-Gly that is also called the "spring fragment" and is repeated six times in the important skin protein, elastin molecule.

The manufacturer made a double-blind, one-month long clinical study on 10 women and found that twice a day application of 4%  Biopeptide El improved skin firmness by 33% and skin tone by 20%. 

What-it-does: chelating

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.

Citric Acid - goodie
What-it-does: exfoliant, buffering

Citric acid comes from citrus fruits and is an AHA. If these magic three letters don’t tell you anything, click here and read our detailed description on glycolic acid, the most famous AHA. 

So citric acid is an exfoliant, that can - just like other AHAs - gently lift off the dead skin cells of your skin and make it more smooth and fresh. 

Expand to read more

There is also some research showing that citric acid with regular use (think three months and 20% concentration) can help sun-damaged skin, increase skin thickness and some nice hydrating things called glycosaminoglycans in the skin. 

But according to a comparative study done in 1995, citric acid has less skin improving magic properties than glycolic or lactic acid. Probably that’s why citric acid is usually not used as an exfoliant but more as a helper ingredient in small amounts to adjust the pH of a formulation. 

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.

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.

Expand to read more

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

A little helper ingredient that works as a preservative. It works against bacteria and some species of fungi and yeast. It's often combined with IT-preservative, phenoxyethanol.

Also-called: Fragrance, Parfum;Parfum/Fragrance | 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 than fragrance is not your best friend - no way to know what’s really in it.  

Expand to read more

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!). 

What-it-does: perfuming

A common fragrance ingredient that smells like jasmine. It is one of the “EU 26 fragrances” that has to be labelled separately because of allergen potential. Best to avoid if your skin is sensitive.

Also-called: Lilial | What-it-does: perfuming

A common fragrance ingredient that has a nice floral scent and also goes by the name Lilial. It’s one of the “EU 26 fragrances” that has to be labelled separately (and cannot be simply included in the term “fragrance/perfume” on the label) because of allergen potential. Best to avoid if your skin is sensitive. 

Limonene - icky
What-it-does: perfuming, solvent, deodorant

A super common and cheap fragrance ingredient. It's in many plants, e.g. rosemary, eucalyptus, lavender, lemongrass, peppermint and it's the main component (about 50-90%) of the peel oil of citrus fruits.

It does smell nice but the problem is that it oxidizes on air exposure and the resulting stuff is not good for the skin. Oxidized limonene can cause allergic contact dermatitis and counts as a frequent skin sensitizer

Expand to read more

Limonene's nr1 function is definitely being a fragrance component, but there are several studies showing that it's also a penetration enhancer, mainly for oil-loving components.

All in all, limonene has some pros and cons, but - especially if your skin is sensitive - the cons probably outweigh the pros.  

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 emollient | viscosity controlling
irritancy, com. 0, 2-3
A common multi-tasker fatty acid that works as an emollient, thickener and emulsion stabilizer. [more]
what‑it‑does emollient | viscosity controlling
irritancy, com. 1, 2
A super common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams. [more]
what‑it‑does emulsifying | surfactant/cleansing
irritancy, com. 3, 2
A common functional ingredient that helps to keep the oil-loving and water-loving ingredients together (emulsifier), stabilizes and thickens the products.  [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 emollient
irritancy, com. 3, 3-5
A clear, colorless oil-like liquid that's used as a fast-spreading, non-greasy emollient. [more]
what‑it‑does emollient
An emollient ester giving a long-lasting lubricious skin feel.  [more]
what‑it‑does emollient
irritancy, com. 0, 1
A very common silicone that gives both skin and hair a silky smooth feel. It also forms a protective barrier on the skin and fills in fine lines. Also used for scar treatment. [more]
what‑it‑does emollient | solvent
It's a super commonly used water-thin volatile silicone that gives skin and hair a silky, smooth feel.  [more]
what‑it‑does emollient | antimicrobial/antibacterial
An often used emollient with a light and silky feel. It's very mild to both skin and eyes and spreads nicely and easily. It's often used in sunscreens as it's also an excellent solvent for sunscreen agents. 
what‑it‑does emollient
A very common emollient that makes your skin feel nice and smooth. Comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. [more]
what‑it‑does emollient
irritancy, com. 0, 1
what‑it‑does emollient
what‑it‑does skin-identical ingredient | emollient
irritancy, com. 0, 1
An emollient and natural moisturizer that can be found also in the sebum (oily stuff our skin produces). It leaves a nice non-greasy, non-heavy feeling on the skin. [more]
what‑it‑does skin-identical ingredient | emollient
irritancy, com. 0, 0
It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
The thing in the pee that is also a natural moisturizing factor (NMF) with mild keratolytic and strong skin moisturizing superpowers. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
It's an important skin-identical ingredient and great natural moisturizer that helps the skin to hold onto water and stay nicely hydrated. [more]
what‑it‑does emollient | viscosity controlling
irritancy, com. 1, 2
A super common multitasker ingredient that gives your skin a nice soft feel (emollient) and gives body to creams. [more]
what‑it‑does emollient
Macadamia nut oil - A highly emollient oil rich in oleic acid (50-67%) and a rare fatty acid called palmitoleic acid (12-25%). It gives the skin a soft, supple and "cushiony" feel. [more]
what‑it‑does emollient
irritancy, com. 0, 0-2
Jojoba oil - a wax ester (chemically not a real oil), that's very similar to human sebum. It's uniquely excellent at helping the skin with its protective barrier and helping it to stay moisturized. [more]
what‑it‑does emollient
thickening/gelling agent, as a compacting agent for pressed powders (ATO grade), and improves heat stability of emulsions.
what‑it‑does buffering
irritancy, com. 0, 2
Helps to set the pH of a cosmetic formulation to be right. It’s very alkaline. [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does moisturizer/humectant | solvent
irritancy, com. 0, 1
An often used glycol that works as a solvent, humectant, penetration enhancer and also gives a good slip to the products. [more]
what‑it‑does antioxidant
irritancy, com. 0, 0
A form of vitamin E that works as an antioxidant. Compared to the pure form it's more stable, has longer shelf life, but it's also more poorly absorbed by the skin. [more]
what‑it‑does soothing
irritancy, com. 0, 0
Super common soothing ingredient. It can be found naturally in the roots & leaves of the comfrey plant, but more often than not what's in the cosmetic products is produced synthetically. It's not only soothing but it' [more]
what‑it‑does moisturizer/humectant
A type of sugar that has water-binding properties and helps to keep your skin hydrated. 
what‑it‑does perfuming
The essential oil coming from the rind of the grapefruit. Its main component (86-95%) is limonene, the super common fragrant ingredient. [more]
what‑it‑does antioxidant
irritancy, com. 0, 2
An oil soluble vitamin C derivative that has mixed data about its effectiveness. [more]
what‑it‑does surfactant/cleansing | emulsifying | surfactant/cleansing
what‑it‑does antimicrobial/antibacterial | solvent
irritancy, com. 0, 0
what‑it‑does moisturizer/humectant
what‑it‑does moisturizer/humectant
A biocompatible copolymer with a similar structure to cell membrane ingredient, phospholipid. It's a good skin moisturizer and can also help to reduce irritation. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
It's the salt form of famous humectant and natural moisturizing factor, hyaluronic acid. It can bind huge amounts of water and it's pretty much the current IT-moisturizer. [more]
what‑it‑does cell-communicating ingredient
Biopeptide El - A six amino acid peptide that is claimed to improve firmness (by 33% in one month) and skin tone (by 20%). [more]
what‑it‑does chelating
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]
what‑it‑does exfoliant | buffering
An AHA that comes from citrus fruits. It is usually used as a helper ingredient to adjust the pH of the formula. [more]
what‑it‑does preservative
A preservative that works mainly against fungi. Has to be combined with other preservatives. [more]
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 preservative | antimicrobial/antibacterial
A little helper ingredient that works as a preservative. It works against bacteria and some species of fungi and yeast. [more]
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]
what‑it‑does perfuming
A common fragrance ingredient that smells like jasmine. It is one of the “EU 26 fragrances” that has to be labelled separately because of allergen potential. [more]
what‑it‑does perfuming
A common fragrance ingredient that has a nice floral scent and also goes by the name Lilial. It’s one of the “EU 26 fragrances” that has to be labelled separately (and cannot be simply included in the term “fragrance/perfume” [more]
what‑it‑does perfuming | solvent
A super common fragrance ingredient found naturally in many plants including citrus peel oils, rosemary or lavender. It autoxidizes on air exposure and counts as a common skin sensitizer. [more]