If you want to understand which hydrophilic facial oil is best to choose — whether for formulating at home or professional development — you should start not with marketing descriptions on labels, but with chemistry. A hydrophilic oil is not just "an oil that washes off with water." It is a carefully balanced system of a lipophilic base and surfactants capable of forming a stable emulsion directly on the skin. This is where the concept of HLB — Hydrophilic-Lipophilic Balance — comes into play. Understanding this parameter allows a formulator not to guess, but to calculate: which emulsifier to choose, in what quantity, and why the cream formula will work. In this article, we will analyse the mechanism of action of hydrophilic oils, the logic of selecting ingredients via HLB, and typical formulation errors.
What is a hydrophilic oil and why does it wash off with water
Classic vegetable oil is a hydrophobic substance. It repels water, does not mix with it, and is difficult to remove from the skin without an additional surfactant. A hydrophilic oil is structured differently: one or more emulsifiers with a high HLB value are intentionally introduced into its composition, allowing the oil phase to disperse in water. Upon contact with damp skin or water, the emulsifiers "capture" the water, form micellar structures, and the entire composition washes off easily, carrying away impurities and makeup.
From the perspective of cosmetic chemistry, a hydrophilic oil is an anhydrous emulsion base that is activated by water at the moment of application. Read more about the logic of anhydrous systems in our article Anhydrous Products: A Complete Guide for Beginners.
Key components of the composition
A typical hydrophilic oil cream formula includes three functional blocks:
- Oil base — one or more vegetable oils, esters, silicones, or combinations thereof. These determine the nutritional profile of the product.
- Emulsifier(s) with high HLB — typically polysorbates (Polysorbate 80, Polysorbate 20), PEG-esters, or their natural analogs (for example, sucrose derivatives). Their task is to ensure self-emulsification upon contact with water.
- Auxiliary ingredients — antioxidants (vitamin E, rosemary extract), fragrances, active components (retinol, rose oil).
HLB: the numerical system that simplifies emulsifier selection
In 1949, chemist William Griffin introduced an elegant tool for selecting surfactants — the HLB (Hydrophile-Lipophile Balance) system. The principle is simple: each non-ionic surfactant is assigned a number from 0 to 20, reflecting the ratio of the hydrophilic and lipophilic parts of the molecule. The higher the value, the more "water-loving" the molecule is.
- HLB 1–3 — antifoaming agents
- HLB 3–6 — emulsifiers for W/O (water-in-oil) emulsions
- HLB 7–9 — wetting agents
- HLB 8–18 — emulsifiers for O/W (oil-in-water) emulsions
- HLB 13–15 — detergents
- HLB 15–20 — solubilizers
For a hydrophilic oil that needs to self-emulsify in water, emulsifiers with an HLB in the 10–15 range are required. This is why Polysorbate 80 (HLB ≈ 15) is so frequently found in cleansing oil formulas — it ensures rapid and complete dispersion in water.
How to calculate the required HLB of the oil phase
Each lipophilic ingredient has its own "Required HLB" — an experimentally determined value at which a given substance is best emulsified. For example:
- Mineral oil — Required HLB ≈ 10–12
- Castor oil — Required HLB ≈ 14
- Isopropyl myristate — Required HLB ≈ 11–12
- Cyclomethicone — Required HLB ≈ 7–8
- Rosehip oil — Required HLB ≈ 7
If the oil phase consists of several components, the required HLB of the mixture is calculated on a weighted basis: each oil is multiplied by its share in the oil phase (as a percentage), and the results are summed. For example, if a formula contains 60% jojoba (Req. HLB 7) and 40% castor oil (Req. HLB 14):
Req. HLB of the mixture = 0.6 × 7 + 0.4 × 14 = 4.2 + 5.6 = 9.8
This value becomes the target when selecting an emulsifier or a blend of them. It is important to note that Req. HLB values are approximate with a margin of error of ±1 unit, so the final stability of the formula must always be verified through testing.
Hydrophilic oil for the face: how to choose the best one for your skin type
The question "which hydrophilic oil for the face is best to choose" does not have a universal answer — it is solved through a combination of the oil base and the fatty acid profile. A detailed breakdown of oils by skin type can be found in our article How to choose oils and butters for your skin type: a guide for beginner formulators. Here, we will focus on formulation logic.
For oily and combination skin
The priority is light, dry oils with a high linoleic acid content: rosehip oil, grapeseed oil, and hemp oil. They absorb quickly, do not create occlusion, and do not exacerbate seborrhea. The emulsifier, Polysorbate 80 at a concentration of 15–25% of the oil phase, will ensure clean rinsing without a film-like feeling.
Example of a basic formula (% of total mass):
- Grapeseed oil — 40%
- Jojoba oil — 30%
- Polysorbate 80 — 25%
- Tocopherol (Vitamin E) — 0.5%
- Fragrance or essential oil — up to 1%
For dry and mature skin
More nourishing oils with a high oleic acid content are appropriate here: avocado, argan, and olive. They are rich in squalane and phytosterols, supporting the barrier function. Since the Required HLB of such oils is lower, you can combine Polysorbate 80 with Polysorbate 20 or use PEG-7 Glyceryl Cocoate for a softer feeling after rinsing.
For sensitive skin
The main criterion is a minimum number of components and the absence of potential irritants. Sunflower oil (high-oleic) or sweet almond oil combined with Coco-Glucoside or Sucrose Cocoate provide gentle cleansing without disrupting the acid mantle. For more on the importance of pH in such formulas, read the article pH in cosmetics: a basic guide for formulators.
Typical mistakes when formulating hydrophilic oils
Even experienced formulators make predictable mistakes when working with this format. Knowing them in advance saves both raw materials and time.
Incorrect calculation of the emulsifier blend HLB
If you are mixing two emulsifiers — for example, Polysorbate 80 (HLB 15) and Span 80 (HLB 4.3) — the final HLB of the system is calculated in the same weighted manner as for the oil phase. Using only a high-HLB emulsifier without a low-HLB component often leads to an unstable emulsion or an unpleasant "slippery" feeling on the skin.
Ignoring oil polarity
Polar esters (isopropyl myristate, C12-15 alkyl benzoate) and non-polar triglycerides behave differently during emulsification. Mixing them in one phase without recalculating the Required HLB of the blend is a direct path to separation. Similar logic applies to butters: the quirks of solid fats are described in detail in the article Butter polymorphism: why cocoa butter acts up and how to work with it.
Lack of antioxidant protection
An anhydrous system does not mean an absence of oxidation. Oils with a high PUFA content (rosehip, hemp) are particularly vulnerable. Tocopherol at a concentration of 0.1–0.5% and rosemary extract (ROE) are the minimum necessary protection. We explain how climate affects the stability of fatty acids in oils in the article How climate affects the composition of fatty acids and essential oils in plants.
Testing and stability of the finished formula
The calculated HLB is a starting point, not a guarantee of stability. A real emulsion system depends on the production temperature, the order of ingredient addition, the phase viscosity, and even the water hardness. Therefore, any new hydrophilic oil formula requires basic testing.
Minimum set of tests
- Emulsification test: add 1 g of the product to 10 ml of warm water (37°C) and evaluate the speed and completeness of dispersion. A good formula forms a uniform milky emulsion within 30–60 seconds.
- Separation test: centrifugation at 3000 rpm for 30 minutes or storage at 40°C for 4 weeks.
- Organoleptics after rinsing: the skin should not feel greasy or "soapy" — only soft and hydrated.
- pH of the aqueous emulsion: measured after a 1:9 dilution with water; 4.5–6.5 is optimal for facial skin.
We analyse the methodology of home formula testing in detail in the material Tribology, gums and gelling agents — it also explains how rheology affects the perception of texture.
FAQ: frequently asked questions about hydrophilic oils
Can Polysorbate 80 be replaced with a natural emulsifier in a hydrophilic oil formula?
Yes, but with caveats. Natural alternatives — Sucrose Cocoate, Coco-Glucoside, PEG-free sucrose esters — provide self-emulsification, however, their effectiveness depends on the polarity of the oil phase. For light oils (jojoba, grape seed), such a replacement works well. For heavy oils (avocado, castor), a higher concentration of natural emulsifier (up to 30–35% of the oil phase) or a combination of several may be required. Always conduct an emulsification test before finalizing the formulation.
Why does cleansing oil leave a greasy film after rinsing?
Most often, the reason is an insufficient amount of emulsifier or an HLB of the system that is too low. If the final HLB of the emulsifiers is lower than the Required HLB of the oil phase, complete dispersion does not occur, and some oil remains on the skin. Increase the proportion of the high-HLB emulsifier or revise the composition of the oil phase towards more polar esters. Also, check the water hardness: hard water reduces the effectiveness of certain surfactants.
Is a preservative needed in cleansing oil?
An anhydrous formula is not a breeding ground for microorganisms on its own, so a classic preservative is not mandatory. However, antioxidant protection (tocopherol, ROE) is necessary to prevent the oils from going rancid. If you add water-soluble actives or extracts, preservation becomes mandatory. Read more about preservation in anhydrous systems on our blog.
Cleansing oil in professional cosmetic formulation practice
Understanding HLB and the mechanism of self-emulsification is not an academic abstraction, but a practical tool. By knowing the required HLB of your oil phase, you can consciously choose emulsifiers, predict the behavior of the formula, and quickly diagnose stability problems. This approach — from chemical logic to the finished product — is the foundation of professional formulation.
If you are interested in how the path from first experiments to confident work with formulations is built, take a look at the article How to become a cosmetic chemist: the path from curiosity to professional formulation. And when you are ready to work with real formulas under the guidance of practising chemists, the Walker Formulation Academy Club is open to those who want to grow systematically, rather than by trial and error.
Choosing the right cleansing oil for the face begins with an understanding of chemistry — and it is this understanding that distinguishes a cream-maker who formulates from one who simply mixes. Learn more about cosmetic chemistry and professional formulation in our courses at the Walker Formulation Academy online school.
