Water: "ALSO-CALLED: Aqua | 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.
Butylene Glycol: "WHAT-IT-DOES: moisturizer/humectant, solvent, viscosity controlling | 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. 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.
Butyloctyl Salicylate: "WHAT-IT-DOES: solvent. A nice, multi-functional helper ingredient that's especially useful in sunscreens. It can solubilize some commonly used UV-filters like Oxybenzone or Avobenzone and it can also help to increase the SPF rating of sunscreens. It's also cosmetically elegant, has excellent spreadability and a pleasant, moisturizing skin feel. Oh, and according to Wikipedia, it even helps to stabilize famously unstable UVA-filter, Avobenzone.
Glycerin: "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.
Diethylamino Hydroxybenzoyl Hexyl Benzoate: "ALSO-CALLED: Uvinul A Plus, DHHB | WHAT-IT-DOES: sunscreen. Diethylamino Hydroxybenzoyl Hexyl Benzoate is a new generation, chemical sunscreen agent (not available in the US due to impossible FDA regulations) that's designed for high UVA protection and high photostability. It gives sun protection in the whole UVA range (320-400 nm) with peak protection at 354nm. It can be used up to 10% worldwide except for the US and Canada.
Hydrogenated Polyisobutene: "WHAT-IT-DOES: emollient, viscosity controlling | IRRITANCY: 2 | COMEDOGENICITY: 1 . A synthetic liquid oil that can replace mineral oil or silicone oils in the cosmetic formulas. There are different grades depending on the molecular weight ranging from very light, volatile, non-residue leaving ones to more substantial, slight residue leaving ones. Apart from leaving the skin soft and smooth (emollient), it's also used as a waterproofing agent in sunscreens or makeup products and as a shine enhancer in lip gloss formulas.
Acrylates Copolymer: "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. It is also used to entrap pigments/inorganic sunscreens within a micron size matrix for even coverage and easy application.
1,2-Hexanediol: "WHAT-IT-DOES: solvent. A really multi-functional helper ingredient that can do several things in a skincare product: it can bring a soft and pleasant feel to the formula, it can act as a humectant and emollient, it can be a solvent for some other ingredients (for example it can help to stabilize perfumes in watery products) and it can also help to disperse pigments more evenly in makeup products. And that is still not all: it can also boost the antimicrobial activity of preservatives.
Niacinamide: "ALSO-CALLED: vitamin B3, nicotinamide | WHAT-IT-DOES: cell-communicating ingredient, skin brightening, anti-acne, moisturizer/humectant. A multi-functional skincare superstar with several proven benefits for the skin. Great anti-aging, wrinkle smoothing ingredient used at 4-5% concentration. Fades brown spots alone or in combination with amino sugar, acetyl glucosamine. Increases ceramide synthesis that results in a stronger, healthier skin barrier and better skin hydration. Can help to improve several skin conditions including acne, rosacea, and atopic dermatitis."