One Ingredient, Multiple Benefits: The Secret of HPMC in Skincare for Thickening, Film-Forming, and Moisturizing
- info@tenessy.com
- Olympic Sports Middle Road, Jinan, Shandong, Chine
In the world of skincare formulation, formulators often face a classic challenge: how to increase a product’s viscosity without sacrificing skin feel, compromising active ingredient release, or losing long-lasting moisturizing power? Traditional single-function thickeners often excel in one area but fall short in others. However, the introduction of Hydroxypropylméthylcellulose (HPMC) offers a near-perfect solution to this dilemma.
HPMC is a non-ionic cellulose ether derived from natural cellulose through chemical modification. Originating from plants, it is scientifically modified to achieve excellent physical and chemical properties. In skincare, it plays three distinct roles simultaneously—thickener, film-former, and moisturizer—truly realizing the concept of “one ingredient, multiple benefits.” This article delves into how HPMC achieves these three core functions in skincare, providing formulators with a scientific and practical application guide.
HPMC stands for Hydroxypropyl Methyl Cellulose. It is produced from natural cellulose (such as cotton linter or wood pulp) through an alkalization process followed by an etherification reaction with methyl chloride and propylene oxide. This process introduces two substituent groups onto the cellulose backbone — methoxy groups (–OCH₃) et hydroxypropoxy groups (–OCH₂CHOHCH₃). This unique combination of groups gives HPMC a distinctive set of properties: it retains the natural, safe, and biodegradable characteristics of cellulose while gaining excellent water solubility and thermal gelation behavior.
Apparence: White or off-white fibrous or granular powder, odorless and tasteless.
Solubilité: Soluble in cold water, only swelling (not dissolving) in hot water, and forming a transparent colloidal solution upon cooling. This characteristic, known as “thermal gelation behavior,” is a key feature distinguishing it from other thickeners.
Stabilité: The viscosity of its aqueous solution remains stable within the pH range of 3.0–11.0, unaffected by pH changes.
Safety: HPMC is not absorbed or metabolized by the body and has excellent biocompatibility.
Because of its combination of safety and functionality, HPMC is not only widely used in skincare but also plays important roles in the industrie alimentaire (as a thickener and emulsifier), the pharmaceutical field (as a sustained-release matrix for tablets and a thickener for eye drops), and the construction material industry (as a water retention agent for cement).
Thickening is the most fundamental and intuitive function of HPMC in skincare. In various formulations such as cleansers, serums, and lotions, HPMC delivers excellent thickening effects at scientifically controlled concentrations, while avoiding the “pilling” or white residue issues often associated with traditional Carbomer.
Mechanism of Action
HPMC molecular chains contain a large number of hydroxyl groups (–OH) et ether bonds (–O–) . These hydrophilic groups form strong hydrogen bonds with water molecules, causing the HPMC chains to hydrate and extend fully in water. As the chains extend and entangle, the flow of water is restricted, and the macroscopic viscosity of the system increases.
Formulation Applications
Amino Acid Cleansing Mousse/Syrup: HPMC gives the cleansing syrup an ideal pourable gel texture and provides an excellent pump dispensing experience. Studies have found that HPMC-thickened cleansers require a very low minimum pump force, dispensing smoothly without splashing. Simultaneously, it has almost no negative impact on foam performance, preserving fine, rich lather — something many traditional thickeners fail to achieve.
Soap-Based Body Wash: Compared to Hydroxyéthylcellulose (HEC), HPMC demonstrates better thickening efficiency and viscosity stability in soap-based systems. This means formulators can achieve higher, more stable viscosity at the same addition level.
Dosage recommandé
The recommended usage range for HPMC in skincare is 0.2%–1.0% , depending on the desired viscosity and skin feel. Gel products typically require higher amounts (closer to 1%), while fluid products can be controlled at 0.2%–0.5%.
The film-forming property of HPMC is its second core function. When a product containing HPMC is applied to the skin and the water evaporates, the HPMC molecules form a transparent, flexible, and breathable film on the skin’s surface.
Mechanism of Action
During and after application, as water evaporates from the HPMC solution, the dispersed HPMC molecules gradually approach each other, entangle, stack, and ultimately form a continuous, dense, solid film. The unique feature of this film is that it offers both barrier properties and breathability, without making the skin feel “tight” or “suffocated.”
Formulation Applications
Sun Care Products: The film formed by HPMC helps distribute sunscreen agents evenly across the skin’s surface, improving the uniformity et la durabilité of sun protection. This film also imparts some résistance à l'eau to the product, reducing sunscreen loss due to sweating.
Color Cosmetics & Base Makeup: In foundations and primers, the film-forming property of HPMC helps the makeup adhere better and last longer, preventing caking or settling into fine lines. It also imparts a smooth, refined tactile sensation to the skin, providing an ideal base for subsequent makeup application.
Masks & Serums: In sheet masks or sleeping masks, the physical barrier formed by HPMC helps reduce Transepidermal Water Loss (TEWL) , prolonging the moisturizing effect. Adding HPMC to wash-off or peel-off masks enhances adhesion, preventing the mask from dripping before it dries.
The moisturizing function of HPMC is closely related to the previous two functions, achieved through two mechanisms:
Mechanism 1: Physical Barrier Water Locking
The direct benefit of film-forming is physical water locking. The HPMC film formed on the skin acts like an “invisible cling wrap,” effectively reducing the evaporation of internal moisture to the external environment and maintaining the hydration state of the stratum corneum. Studies have shown that HPMC can significantly slow down the rate of moisture loss from the skin’s surface.
Mechanism 2: Binding Water via Hydrophilic Groups
The numerous hydroxyl and ether groups in HPMC molecules have a strong affinity for water, enabling them to bind and retain water molecules, allowing them to stay on the skin’s surface and within the superficial layers of the stratum corneum for a longer period. This mechanism is similar to that of small-molecule humectants (like glycerin or hyaluronic acid), but the high molecular weight of HPMC means it is not easily absorbed into the skin, thus providing longer-lasting surface residence and a more prolonged sensation of moisture.
Synergy with Other Humectants
Combination with small-molecule glycols (Glycerin, Butylene Glycol, etc.) : Small-molecule humectants penetrate the stratum corneum to attract water from within, while HPMC forms a water-locking film on the surface — internal and external synergy significantly boosts moisturizing effect.
Combination with Sodium Hyaluronate: Hyaluronic acid is a well-known potent humectant but is expensive. Blending an appropriate amount of HPMC can reduce formulation costs without compromising skin feel, while maintaining excellent moisturizing performance.
The dissolution of HPMC has a specific requirement: it dissolves only in cold water, not in hot water. The correct dissolution steps are as follows:
Dispersion: Add the HPMC powder to 80–90°C hot water while stirring. At this temperature, HPMC only swells and disperses without dissolving, preventing clumping.
Cooling: Continue stirring and cool the system to room temperature (or accelerate cooling using an ice bath). As the temperature drops, HPMC begins to dissolve, and the system gradually becomes transparent and viscous.
Standing for Deaeration: The fully dissolved solution may contain tiny air bubbles. Allow it to stand for 2–4 hours or use vacuum deaeration to obtain a highly transparent gel.
Valeur du pH: The thickening performance of HPMC is highly stable within the pH 3–11 range. Studies have found that increasing the pH of cleansing systems promotes the swelling and dispersion of HPMC at low temperatures, effectively suppressing gelation tendencies and sedimentation issues. This is critical for the low-temperature stability of winter products.
Salt Influence: HPMC is a non-ionic polymer and is relatively sensitive to electrolytes. High concentrations of inorganic salts can weaken its hydration ability, leading to a decrease in viscosity. In formulations with high salt content (e.g., certain surfactant systems), it may be necessary to increase the HPMC dosage appropriately or choose a product with a higher viscosity grade.
Temperature: Aqueous HPMC solutions undergo a reversible gelation transition when heated to the gelation temperature (typically 58–90°C, depending on the degree of substitution). The solution changes from transparent to turbid, and viscosity drops sharply. This characteristic makes HPMC particularly suitable for products requiring hot filling, as the system has low viscosity and good fluidity at high temperatures, returning to the ideal viscosity after filling and cooling.
Synergy:
Combining with Carbomer can optimize the spreadability and adhesion of gels. A study on anti-acne gel showed that the combination of 1.96% HPMC + 0.53% Carbomer 940 achieved ideal rheological properties and physical stability.
Blending with other natural polysaccharides like Xanthan Gum or Guar Gum can create more complex rheological profiles, achieving the desired “shear-thinning, static-thickening” tactile sensation.
Antagonism:
Avoid mixing directly with high concentrations of electrolytes. It’s best to dissolve HPMC completely before adding salts.
Some high concentrations of polyols (exceeding 30%) may inhibit the hydration of HPMC. The addition order may need adjustment, or the HPMC dosage may need to be increased.
As consumer awareness of ingredient sourcing, safety, and sustainability in cosmetics grows, HPMC is facing new market opportunities:
Natural Origin: Derived from plant cellulose, HPMC meets consumer expectations for “derived from nature” and is a preferred thickener for many ‘clean beauty’ brands.
Ideal Partner for Sulfate-Free Systems: Thickening is a well-known technical challenge for the increasingly popular sulfate-free (SLS/SLES-free) cleansing and hair care products. Research confirms that HPMC can effectively thicken amino acid surfactant systems without affecting foamability, making it a ‘star ingredient’ in this field.
Vegan and Cruelty-Free: HPMC can replace some animal-derived gelatins (e.g., used in certain capsules or gummy products), aligning with the values of vegans.
Functional Gels: Combined with other active ingredients (e.g., anti-acne agents, whitening agents), HPMC provides an excellent skin feel in gel products while enabling sustained release of actives, reducing irritation and prolonging the duration of action.
Spray Products: Low-viscosity HPMC solutions have good sprayability and form a transparent film upon drying. They are suitable for sunscreen sprays, moisturizing mists, setting sprays, etc., offering convenient application and effective protection or hydration.
In today’s skincare formulation landscape, which increasingly values simplicity, efficiency, and multi-functionality, HPMC has become an indispensable ‘versatile player’ for formulators, thanks to its three-in-one functional combination of thickening, film-forming, and moisturizing. It not only enhances product viscosity and stability but also directly improves the skin’s feel and condition through its film-forming and moisturizing benefits, ultimately delivering a superior user experience.
For brands committed to developing high-quality, clean and safe, and simply formulated skincare products, HPMC is undoubtedly a classic ingredient worthy of in-depth research and application.
TENSITE offers a variety of Hydroxypropyl Methyl Cellulose (HPMC) products, covering different viscosity grades and substitution types, suitable for the formulation development of various skincare products such as cleansers, serums, lotions, masks, and sunscreens. For sample testing or technical support, please feel free to contact our technical team.
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