Water is a great solvent. It’s neutral and doesn’t provide any strong positive or negative effects. It just helps components to mix better and to transport active components.
Propylene Glycol is a useful componet with many positive effects. It’s a very good moisturizer. It helps to deliver ingredients into deeper layers of the skin. It creates a protective layer on the skin preventing water loss. The component is researched very well and doesn’t have notable side effects. It’s used even for making food.
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Dimethicone
Roles: Skin conditioning, Antifoaming, Emollient
Silicones
Dimethicone is the most popular silicone. It makes the skin softer and forms a film adding smooth and silky feeling. This film not only improves how the skin feels but also works as a protective barrier. It also improves the visual appearance of your skin by filling small wrinkles. That's why some people think dimethicone removes wrinkles. Actually, it does not. It's just a visual effect.
One of the most important characteristics of this component is that it helps to spread other ingredients evenly on the surface to provide good coverage. It's very important because you want all your skin cells to receive an equal proportion of the components.
Dimethicone is considered as safe, but remember that it is rather difficult to wash off! This may lead to clogged pores and acne if you use it too often and don't wash off quite well.
Triethanolamine is a pH adjuster. It is a toxic component that can be absorbed by the skin and detected in blood later. It can be a dermal irritant. Though it's considered safe, you should think before using it in skincare. There are many products on the market without Triethanolamine.
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Phenoxyethanol
Roles: Fragrance, Preservative
Antiseptic
Phenoxyethanol is one of the most popular preservatives. It kills bacteria and makes the product live longer. Manufacturers like this ingredient because it can dissolve in any liquid, even in oils.
Another purpose of this component is the fixation of aromas in perfumery. Phenoxyethanol is also used as a strong antiseptic and a good antibacterial agent. It is widely used in dermatological cosmetics alongside natural antiseptics such as chamomile, sage, and calendula.
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PEG/PPG-17/18 Dimethicone
Roles: Emulsifying, Surfactant
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Carbomer
Roles: Emulsion stabilizer, Gel forming, Viscosity controlling
Moisturizing
Carbomer is used for formulation purposes. It helps to control the viscosity and flow of a product. It’s considered safe but only if it’s well purified. Poorly purified carbomers may contain benzol which may lead to irritation.
Arginine is an essential amino acid. It works as an antioxidant when used in skincare products. It also helps the skin to regenerate and stay hydrated. In hair care, it is used to decrease damage from oxidative coloring or bleaching.
Linalool gives the product a nice and fresh lavender scent. It can be found in many essential oils. It oxidizes during air exposure and becomes allergenic. It can lead to irritation causing problems for people with sensitive skin. The threat is even higher if the product was opened several months ago. In such products, more Linalool is oxidized.
Cetrimonium Chloride is used mostly for formulation purposes and doesn't provide any strong skincare effects. Used mostly to help mix different components together. It also helps to increase the shelf life of the product. CIR safety report tells that this ingredient was found to be “…safe for use in rinse‐off products and …safe for use at concentrations of up to 0.25% in leave‐on products.”
In the European Union (EU), cetrimonium chloride and steartrimonium chloride were reported to be used as a preservative at up to 0.1%. They are also used in rinse-off hair care products at up to 2.5%, leave-on hair products at up to 1.0%, and in leave-on facial cream products at up to 0.5%.
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Citronellol
Roles: Fragrance, Masking
Allergens
Citronellol makes the product smell better. It’s one of the most frequently used fragrance ingredients in the world. It smells like a fresh cut of apple peel mixed with a citrus scent. It’s also used to enhance flower scent. It has slight anti-bacterial activity.
Beware! This component is in the list of potential allergens and can cause allergic contact dermatitis.
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Hexyl Cinnamal
Roles: Fragrance, Masking
Allergens
Hexyl Cinnamal is a fragrance component that gives the product pleasant cinnamon and light jasmine aroma. It’s also used to enhance other fragrances. It’s considered a skin sensitizer and manufacturers have to call out this component on an ingredient statement.
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Geraniol
Roles: Fragrance, Masking
Allergens
Geraniol is a fragrance ingredient that gives product a nice rose scent. That’s why it’s used by many manufacturers. In addition to its pleasant scent, it also provides an antifungal effect increasing the shelf life of a product. There are several ways of obtaining this ingredient but all of them are chemical.
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Fragrance
Roles: Deodorant, Fragrance, Masking
Fragrances
Fragrance is a mix of chemical ingredients (usually 20-30 chemicals but up to 200 sometimes) that help the product to smell better. It can hide many bad things. Synthetic fragrances may contain many different chemicals, but manufacturers don’t want to reveal each of them for some reason and hide them behind the word "Fragrance".