Follow us on our new Insta page »
Rationale #6 The Serum

#6 The Serum

6 the serum is designed to support skin rejuvenation and essential nourishment throughout the night
Uploaded by: mon on

Rationale #6 The Serum
Ingredients explained

What-it-does: emollient, perfuming | Irritancy: 0 | Comedogenicity: 2-4

A super common, medium-spreading emollient ester that gives richness to the formula and a mild feel during rubout. It can be a replacement for mineral oil and is often combined with other emollients to achieve different sensorial properties.

Retinol - superstar
Also-called: Vitamin A, Form of Retinoids | What-it-does: cell-communicating ingredient
  • Retinol (pure Vitamin A) is probably the most proven anti-aging ingredient available OTC
  • It has to be converted in the skin to retinoic acid to work its magic
  • Once converted, it has the same effect as all-trans-retinoic acid, aka tretinoin
  • A generally accepted ballpark number is that retinol is 10-to-20 times less potent than retinoic acid
  • It makes skin less wrinkled, smoother, firmer and tighter
  • It might also be helpful for acne prone skin as it normalizes keratinization and makes the pores produce less sebum
  • Possible side effects and irritation are also much less than with retinoic acid
  • Do not use whilst pregnant
Read all the geeky details about Retinol here >>

Also-called: Vitamin K1

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.

We don't have description for this ingredient yet.

What-it-does: antioxidant

We don't have description for this ingredient yet.

Lecithin - goodie
What-it-does: emollient, emulsifying

A very common ingredient that can be found in all cell membranes. In cosmetics it's quite the multi-tasker: it's an emollient and water-binding ingredient but it's also an emulsifier and can be used for stabilization purposes. It's also often used to create liposomes

Also-called: 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. 

This ingredient name is not according to the INCI-standard. :( What, why?!

This ingredient name is not according to the INCI-standard. :( What, why?!

We don't have description for this ingredient yet.

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

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.  

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. 

Also-called: Bergamot Fruit Oil | What-it-does: perfuming

The essential oil coming from the fruit (probably the rind) of the bergamot orange.  It's a common top note in perfumes and contains (among others) fragrant compounds limonene (37%), linalyl acetate (30%) and linalool (8.8%). 

A well-known issue with bergamot oil (apart from the fragrance allergens) is that it contains phototoxic compounds called furanocoumarins, but more and more commonly furanocoumarin-free versions are used in cosmetic products. Still, if you have sensitive skin and prefer fragrance-free products, bergamot oil is not for you.

Citral - icky
What-it-does: perfuming

It’s a common fragrance ingredient that smells like lemon and has a bittersweet taste.  It can be found in many plant oils, e.g. lemon, orange, lime or lemongrass. 

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.

Also-called: Sweet Orange Peel Oil, Citrus Sinensis Oil | What-it-does: perfuming

The essential oil coming from the rind of the orange (the sweet one). In general, the main component of citrus peel oils is limonene (83-97% for sweet orange 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. Orange peel contains less of it than some other citruses (like bergamot or lime), but still, be careful with it especially if it is in a product for daytime use.  

Linalool - icky
What-it-does: perfuming, deodorant

Linalool is a super common fragrance ingredient. It’s kind of everywhere - both in plants and in cosmetic products. It’s part of 200 natural oils including lavender, ylang-ylang, bergamot, jasmine, geranium and it can be found in 90-95% of prestige perfumes on the market. 

The problem with linalool is, that just like limonene it oxidises on air exposure and becomes allergenic. That’s why a product containing linalool that has been opened for several months is more likely to be allergenic than a fresh one.

A study made in the UK with 483 people tested the allergic reaction to 3% oxidised linalool and 2.3% had positive test results. 

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

The essential oil coming from the rind of the lemon that we make (or should make) lemonade from. In general, there are two problems with citrus peel oils: first, they are essentially the fragrant component, limonene in disguise (they are about 85-98% limonene).

Second, they contain the problematic compounds called furanocoumarins that make them mildly phototoxic. Lemon peel contains a medium amount of them, more than sweet orange but less than bergamot. Be careful with it especially if it is in a product for daytime use.  

Geraniol - icky
What-it-does: perfuming

Geraniol is a common fragrance ingredient. It smells like rose and can be found in rose oil or in small quantities in geranium, lemon and many other essential oils. 

Just like other similar fragrance ingredients (like linalool and limonene) geraniol also oxidises on air exposure and becomes allergenic. Best to avoid if you have sensitive skin.

What-it-does: perfuming

We don't have description for this ingredient yet.

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

what‑it‑does emollient | perfuming
irritancy, com. 0, 2-4
A super common, medium-spreading emollient ester that gives richness to the formula and a mild feel during rubout. [more]
what‑it‑does cell-communicating ingredient
Vitamin A - the most proven anti-aging ingredient available OTC that can smooth wrinkles and make skin firmer. It might also be useful for acne-prone skin as it normalizes keratinization. [more]
what‑it‑does antioxidant
what‑it‑does emollient | emulsifying
It's quite the multi-tasker: an emollient and water-binding ingredient but also an emulsifier and can be used for stabilization purposes. It's also often used to create liposomes.  [more]
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 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]
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 perfuming
The essential oil coming from the fruit (probably the rind) of the bergamot orange.  It's a common top note in perfumes and contains (among others) fragrant compounds limonene (37%), linalyl acetate (30%) and linalool (8.8%).  A well-known issue with bergamot oil (apart from the fragrance allergens) is that it contains phototoxic  [more]
what‑it‑does perfuming
A common fragrance ingredient that smells like lemon. [more]
what‑it‑does perfuming
The essential oil coming from the rind of the orange. Its main component (83-97%) is limonene, the super common fragrant ingredient. [more]
what‑it‑does perfuming
A super common fragrance ingredient that can be found among others in lavender, ylang-ylang, bergamot or jasmine. The downside of it is that it oxidises on air exposure and might become allergenic. [more]
what‑it‑does perfuming
The essential oil coming from the rind of the lemon. Its main component (83-97%) is limonene, the super common fragrant ingredient. [more]
what‑it‑does perfuming
A common fragrance ingredient that smells like rose and can be found in rose oil. [more]
what‑it‑does perfuming