Dermalogica Pro-Collagen Banking Serum Versus Dermalogica Circular Hydration Serum

Citrus Aurantium Bergamia Fruit Oil is the oil from the bergamot orange and is primarily used as a fragrance. It has a "fresh" and "bright orange" scent.

The main aroma compounds found in this ingredient are limonene (~27-52%), linalool (~2-22%), and linalyl acetate (~27-40%). These are known EU fragrance allergens.

Citrus Limon Peel Oil is created from the peels of the lemon. It is used to add a lemon-scent to products. Lemon peel oil also has antibacterial, antifungal, and antioxidant properties. However, it may also cause phototoxicity and sensitize skin.

Lemon peel oil contains limonene, a skin sensitizing ingredient. Another component is furanocoumarin, which induces phototoxicity in skin.

This ingredient is also known as grapefruit peel oil. It is mainly used as a fragrance/perfuming ingredient and is made up of about 99-92% limonene.

Though in vitro or food science has shown this oil to be antibacterial, possess antioxidant activity, and be anti-inflammatory, there's very little research testing it directly on human skin or in cosmetics.

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:

Hydrolyzed Rice Protein is protein extracted from rice. This ingredient is rich in antioxidants and peptides.

Studies show this ingredient may help with blocking the melanin creation process when skin is exposed to UV.

Jasminum Sambac Flower Extract is a fragrance.

Juniperus Virginiana Oil is the volatile oil obtained from the fruits and leaves of the Red Cedar tree. This tree is native to North America.

Limonene is a fragrance that adds scent and taste to a formulation.

It's found in the peel oil of citrus fruits and other plants such as lavender and eucalyptus. The scent of limonene is generally described as "sweet citrus".

Linalool is a fragrance and helps add scent to products. It's derived from common plants such as cinnamon, mint, citrus, and lavender.

Like Limonene, this ingredient oxidizes when exposed to air. Oxidized linalool can cause allergies and skin sensitivity.

Methylpropanediol is a synthetic solvent and humectant.

As a solvent, it helps dissolve other ingredients, helping to evenly distribute ingredients throughout the product. This ingredient has also been shown to have antimicrobial properties which makes it a preservative booster.

Pentylene Glycol (1,2-pentanediol) is a multitasking little diol with three main roles in a formula:

Research on alkanediols (the family pentylene glycol belongs to) show they work by disrupting microbial cell membranes. This disruption helps the primary preservative system in a product work more effectively at lower doses.

Polyglutamic Acid is made up many glutamic acids chained together. It is created from bacterial fermentation.

This ingredient is an effective skin hydrator and may help speed up wound healing. As a humectant, it draws and holds water to the skin. This ingredient is often compared to hyaluronic acid or glycerin. Similarly to hyaluronic acid, it can vary in molecular weights. This means polyglutamic acid is capable of bringing hydration to lower levels of the skin.

Polysorbate 20 is a gentle, water-soluble emulsifier and mild surfactant. It stops oil and water from separating to keep your formulas blended and stable.

It also acts as a mild penetration enhancer by helping active ingredients absorb slightly better.

Potassium Sorbate is a preservative used to prevent yeast and mold in products. It is commonly found in both cosmetic and food products.

This ingredient comes from potassium salt derived from sorbic acid. Sorbic acid is a natural antibiotic and effective against fungus.

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

It’s often used to:

Santalum Album Oil is created from the Santalum album, or the East Indian sandalwood tree. This oil has fragrance and masking properties due to its unique scent.

Sandalwood may sensitize the skin for those sensitive to fragrances.

Sclerotium Gum is a natural sugar-based fiber made by fermenting a fungus called Sclerotium rolfsii. It's often used as the plant-friendly alternative for synthetic thickeners like carbomer.

In skincare, it works as a thickener, gel former, and stabilizer that keeps heavy ingredients suspended so a product does not separate.

Sodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.

Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.

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.

Sodium Hydroxide is also known as lye or caustic soda. It is used to adjust the pH of products; many ingredients require a specific pH to be effective.

In small amounts, sodium hydroxide is considered safe to use. However, large amounts may cause chemical burns due to its high alkaline.

This oil is from the wild marigold plant (not the same as Calendula Officinalis, a different marigold). The main components of this ingredient are dihydrotagetone, ocimene, tagetone, and limonene.

This ingredient is phototoxic and is set at a maximum concentration of 0.01% in leave-on products.

Tetrasodium Glutamate Diacetate is a chelating agent. Chelating agents help prevent metal ions from binding to other ingredients. This helps prevent unwanted effects and reactions from a product. These metal ions may come from water and are found in miniscule amounts.

Tetrasodium Glutamate Diacetate can also help other preservatives be more effective.

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.