Kiehl's Better Screen UV Serum SPF 50+ Facial Sunscreen With Collagen Peptide Versus COSRX Vitamin E Vitalizing Sunscreen SPF 50+ - EU

Glyceryl Stearate is a mix of glycerin and stearic acid.

It is used to stabilize the mixing of water and oil ingredients. By preventing these ingredients from separating, it can help elongate shelf life. It can also help thicken the product's texture.

Homosalate is a chemical sunscreen filter that provides protection in the UV-B range (280nm - 320 nm), with a peak protection at 306 nm. It is internationally approved for use in sunscreens.

Homosalate is not photo-stable, meaning it's strength as a UV filter degrades over time with exposure to the sun. Because of this, it's often used in combination with other chemical sunscreen filters as avobenzone (which protects from the UV-A range). Homosalate also helps act as a solvent for harder-to-dissolve UV filters.

Octocrylene protects skin from sun damage. It absorbs UV-B with peak absorption of 304 nm. It is a common sunscreen ingredient and often paired with avobenzone, a UVA filter. This is because octocrylene stabilizes other sunscreen ingredients by protecting them from degradation when exposed to sunlight. Octocrylene is a photostable ingredient and loses about 10% of SPF in 95 minutes.

Octocrylene also acts as an emollient, meaning it helps skin retain moisture and softens skin. It is oil-soluble and hydrophobic, enhancing water-resistant properties in a product.

Polysorbate 20 is made by combining ethoxylation of sorbitan, ethylene oxide, and lauric acid. It is a mild cleansing agent, surfactant, and emulsifier.

As a surfactant, it helps collect dirt and oils for washing. Emulsifiers prevent oils and water from separating.

Propanediol is an all-star ingredient. It softens, hydrates, and smooths the skin. 

It’s often used to:

Tocopherol (also known as Vitamin E) is a common antioxidant used to help protect the skin from free-radicals and strengthen the skin barrier. It's also fat soluble - this means our skin is great at absorbing it.

Vitamin E also helps keep your natural skin lipids healthy. Your lipid skin barrier naturally consists of lipids, ceramides, and fatty acids. Vitamin E offers extra protection for your skin’s lipid barrier, keeping your skin healthy and nourished.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.