What are Moisturizers?
What are Moisturizers?
Human skin is covered with the stratum corneum, which is a thin biological protective membrane. This stratum corneum exposed to the external world allows us to live in the dry atmosphere without losing water.
- The stratum corneum is thin and supple.
- It contributes to maintenance of healthy skin by preventing loss of body water.
Healthy skin is generally said to have a water content of 10 to 20%.
The term “Moisturizer” resonates with the consumer and denotes improvement of skin, thus projecting the perception of healthy skin. In general terms, “moisturization” (or skin conditioning) is the kingpin of topical skin treatment.
Skin discomfort is not acceptable, and moisturizers containing primarily emollients and humectants can help alleviate the symptoms of “dry” skin and uncomfortable skin symptoms.
Moisturizers are misconstrued with terms such as “Humectants” and “Emollients”, and are usually associated with skin or hair conditioning.
So, choosing the right moisturizer, skin hydrating agent, and skin softening/soothing ingredients requires:
- Knowledge of their chemical, physical and performance properties, as
well as
- How to best utilize them against the target performance claim, consumer
perception and expectations
Let's explore the classification and performance matrix of moisturizing agents...
Classification of Moisturizers
Classification of Moisturizers
Since dry skin and combinations of it require barrier repair of some type, it
will be necessary to consider the incorporation of four classes of functional
ingredients to achieve optimal consumer perceived moisturization.
The four
classes of functional ingredients are:
- Humectants help to modulate water content by enhancing surface water availability.
- Occlusivity agents, typically denoted as moisturizers, modulate water content by slowing down TEWL.
- Keratolytic agents stimulate cell renewal by cleaning dead cells from the skin's surface and exciting new cells to form at the surface for a better and healthier barrier.
- Emollients provide topical aesthetics and lubrication that enhance the perception of soft, smooth skin; they can provide some level of moderate TEWL improvement topically.
Classes of Functional Ingredients
"Moisturizer" technologies utilized to provide consumer perceived moisturization are as diverse, in a general sense, as the total available chemistry in personal care. Achieving acceptable moisturization does not necessarily require new technology, but can draw from the extensive list of already available chemistries
mainly:
- Esters
- Hydroxyl-functional
- Vegetable oils/butters
- Organic salts, and
- Nitrogen-containing
There are many options to enhance moisturization performance in skin and hair care formulations.
Generally, there is required a balance of the four categories listed above to elicit both a consumer perceived moisturization affect and a clinical enhanced performance. Further, there is a synergistic gain when combinations of each technology classification are employed.
Let’s discuss each of them in detail...
Humectants
Group of hydroscopic substances – Attracts and retains the moisture in the air or skin.
Strengths: Ability to modulate available moisture on and in the skin.
Hurdles: Tend to be aesthetics.
Opportunities: Synergies to enhance humectancy (seen as TEWL and Conductance improvements) at reduced levels, and thus improved aesthetics and performance.
| Classification |
Examples |
Trihydroxy Polyol –
Best humectant with desquamation properties; high conductance generator |
|
Alkanol Amine –
Provide synergy with glycerin; increased skin barrier build |
|
Carbohydrate –
Work as a moderate humectant; good aesthetic enhancing properties combined with Glycerin |
|
Polyols –
Hydroxyl groups hydrogen bonding to water |
|
Carbamide –
Good humectant with keratolytic properties; good synergy with glycerin and other humectants |
|
Carboxylic
Acid –
One of the original NMF ingredients |
|
Amino Sugars –
Reported humectancy; noted for the potential for skin turn-over properties |
|
Quaternary Amine –
Mild humectant with aesthetic enhancing properties |
|
Sebaceous Gland Extract –
Strong occlusivity agent with hydrating properties and increased cell turnover; reported improved skin barrier repair |
- Lanolin & Derivatives
- Alcohol-Acetylated
|
Organic Acid Salt –
Strong hydrating properties & some keratolytic action |
|
| Material Selector – Check Out the List of Humectants Here »
|
Humectants Functionality Matrix
Occlusivity Agents
Air and Water barrier – Prevents significant evaporation of skin's internal water, and prevents topical ingredients from penetrating the skin's barrier.
Strengths: They are natural skin's moisturization balance.
Hurdles: Tend to be aesthetics.
Opportunities: Utilization of petrolatum with aesthetic enhancing occlusivity agents.
| Classification |
Examples |
Hydrocarbon –
Occlusivity agents (Petrolatum considered the benchmark), but can have some tacky aesthetics |
|
Siloxane –
Almost equivalent to petrolatum without the negative aesthetics; excellent combination with Petrolatum to soften skin feel |
|
Nut Butters –
It has very good occlusivity and some humectancy properties; excellent replacement for Petrolatum |
- Shea Butter (and other nut butters)
|
Occlusivity Functionality Matrix
Keratolytic Agents
Benefits: Removal of dead skin to enhance skin barrier repair and renewal.
Strengths: They are more rapid cell turnover to strengthen the skin's barrier.
Hurdles: They are primarily increased skin irritation.
Opportunities: Compatible to skin's pH mantle without loss of the keratolytic properties.
| Classification |
Examples |
Carboxylic Acids –
Strong keratolytic action without the strong skin irritating properties |
|
Fruit Acids –
Excellent keratolytic action, strong skin irritants (before pH modified that can reduce effectiveness) |
|
Diureide –
Keratolytic and desquamation action |
|
Keratolytic Functionality Matrix
Emollients
Generally noted for their enhanced skin aesthetics with improvements in tactile soft/smoothness properties.
They also act as a non-greasy fiction reducer.
Strengths: Ability to modify the skin's tactile surface perception.
Hurdles: Ability to choose the right emollients from the expansive candidates represented by a diverse selection of chemistries.
Opportunities: Understanding the emolliency cascading affects of blended emollients to trigger changing feels during and after application.
| Classification |
Examples |
Siloxane –
A diverse group of compounds from dimethyl substituted to virtually and organic substitution; candidates are measured by compatibility in formula and cost constraints |
- Dimethicone, Gums & Crosspolymer
- Alkyl Methyl (Distearyl Methicone)
- Amino functional (e.g., Amodimethicone)
|
Fatty Acid Esters –
A diverse group of compounds that are selected based on a skin feel; can be combined to create a cascading emolliency |
- Linear (e.g. Cetyl Palmitate, Behenyl Lactate, Archidyl Propionate)
- Branched (e.g. Isonononyl Isononoate Behenyl Isostearate, Triisodecyl Myristate)
|
Glyceride Derivatives –
Provide excellent emolliency and organic coupling; some having good co-emulsification properties |
|
Ether –
Good emolliency |
|
Dimer Dilinoleate Derivatives –
Good emolliency; some having good co-emulsification properties |
|
Polymeric –
A diverse group of compounds based on acrylic, polyether, polyamide, polyurethane chemistry |
|
Vegetable Oils and Derivatives –
A very popular natural choice for emolliency; need to formulate around potential oiliness of straight oil triglycerides |
- Olive Oil and esters/transesters
|
Material Selector – Get the Complete List of Emollients »
|
Emollients Functionality Matrix
Vegetable and natural oils (such as rapeseed oil, sunflower oil and soybean oil, etc.) are desirable emollients offering antioxidant properties in skin care applications. Some of the oils and their properties are listed below.
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Wheat Germ Oil is an antioxidant with more Vitamin E than any other natural oil. It is primarily used as an emollient to moisturize and relieve dry, irritated skin. Wheat Germ Oil possesses cell regenerative properties that make it a good choice for anti-aging formulas.
-
Avocado oil is deeply hydrating and highly compatible with your skin's own oils. It is also a powerful anti-oxidant and is brimming with high levels of chlorophyll, vitamin E and omegas 3 and 9 to improve the health and vitality of your skin.
-
Jojoba oil has excellent inherent emollient and moisturizing properties - coupled to its oxidative stability properties. It is one of the world's top lipid cosmetic ingredients often used in anti-aging skincare.
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Cocoa Butter is one of the most stable fats known, loaded with natural antioxidants that prevent rancidity and give it a shelf life of two to five years. It softens and lubricates the skin, assisting in reducing stretch marks and scars making it an excellent massage cream. It performs as an antioxidant, emollient, and lubricant.
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Sweet almond oil has a long historical use that includes restoring itchy, dry and inflamed skin as well as being a simple emollient. It contains 24% linoleic acid, an incredibly high amount of the antioxidant EFA.
-
Shea Butter is used as an emollient and moisturizer in cosmetics. High in vitamin E, an anti-aging antioxidant that increases micro-circulation, it also contains the antioxidants beta-carotene and vitamin A.
Performance of Moisturizers
Selection Criteria for Your Moisturizer
Starting Point Formulations