Tatcha The Brightening Serum Versus Glow Recipe Guava Vitamin C Dark Spot Treatment Serum

Ethylhexylglycerin is created from glycerin. It is a multitasker ingredient that:

The CIR Expert Panel found minimal skin absorption or sensitization of any kind in a safety assessment. Though this ingredient is considered well-tolerated, a small number of cases of allergic dermatitis have been published since 2002. Just be sure to patch test if you are unsure.

Ferulic Acid is a plant based antioxidant that can be naturally found in the cell walls of grains like rice, oats, and corn. It has antioxidant and antimicrobial properties, and has the ability to boost the performance of other antioxidants as well.

A well-known study found that adding Ferulic Acid to a solution of Vitamins C and E doubled the photoprotection of skin. This is why you'll often see it paired with Vitamin C or Vitamin E serums rather than sold on its own.

Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.

Topically, glycerin does several things at once:

Phenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.

It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.

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

It’s often used to:

Sodium Citrate is the sodium salts of citric acid. In skincare, it is used to alter pH levels and acts as a preservative.

Its main functions are to maintain the pH of a product and neutralize metal ions.

Sodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.

In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.

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.

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.