Water-Based vs Oil-Based Skincare: Does Your Formulation Affect How Active Ingredients Reach the Skin?
It's a regular occurrence in social media for some small skincare brand owners and mis-informed "influencers" to put forward the idea that if a skincare product contains water, or aqua as it appears on the INCI ingredient list, it must contain synthetic preservatives and, in some way, is less effective.
I can confidently state here and now, that this line of thought is misleading and absolutely untrue.
When we talk about skincare, we tend to concentrate on the ingredients.
Aloe Vera. Hyaluronic acid. Flax seed. Jojoba oil. Shea butter. Botanical extracts. Essential oils.
But there is another question that is just as important:
What is carrying those ingredients to the skin?
In cosmetic formulation, this is known as the vehicle or delivery system, and it can have a profound influence on how an ingredient behaves once it has been applied.
This raises an interesting question:
Are water-based skincare products better at delivering active ingredients than oil-based products?
The answer is: sometimes — but it depends entirely on the ingredient and the formulation.
There is no universal rule that water-based products penetrate better, or that oils penetrate better.
The chemistry of the ingredient and the architecture of the formulation are what matter.
Why does water matter?
The outermost layer of our skin, the stratum corneum, is often described as a “brick and mortar” structure.
The corneocytes are the bricks, surrounded by an intercellular lipid matrix that acts rather like the mortar.
This outer layer is remarkably effective at controlling what enters and leaves the skin.
Water plays an important role in its behaviour.
A water-based formulation can immediately increase the hydration of the stratum corneum. Hydrated skin is more flexible and its physical properties change, which can influence the diffusion of certain compounds through the outer barrier.
This is one reason why a moisturising gel or cream can feel so different from an anhydrous facial oil.
But there is another important consideration:
Some skincare ingredients are naturally water-soluble.
Aloe vera, glycerine, hyaluronic acid and flax seed mucilage are obvious examples.
If these ingredients are incorporated into an aqueous phase, they are already in an environment in which they can remain dispersed or dissolved.
That makes water-based formulations particularly useful when the objective is to deliver hydrophilic, or water-loving, ingredients.
What about oil-based skincare?
Oil-based formulations have a completely different set of advantages.
Many biologically interesting compounds are lipophilic, meaning they have an affinity for oils and fats.
Plant oils also contain a complex mixture of fatty acids, triglycerides, sterols, tocopherols and other lipid-soluble constituents.
An oil-based product can therefore act as an excellent vehicle for oil-soluble botanical compounds.
But its role isn’t simply to “carry ingredients deeper”.
One of the major advantages of oils is their ability to act as emollients and, depending on the formulation, provide a degree of occlusion.
Occlusion reduces trans-epidermal water loss (TEWL) — the movement of water from the skin through the epidermis and into the atmosphere.
In simple terms:
Oil can help the skin hold on to the water it already contains.
This is particularly important when supporting the skin’s barrier and maintaining a comfortable level of hydration.
Water-based and oil-based products therefore do different jobs
It can be useful to think of the two systems as complementary rather than competitors.
Water-based formulations
Can be particularly useful for:
- Hydrophilic ingredients
- Aloe vera
- Flax seed mucilage
- Glycerine
- Hyaluronic acid
- Water-soluble botanical extracts
- Lightweight hydration
- Rapidly disappearing textures
Oil-based formulations
Can be particularly useful for:
- Lipophilic ingredients
- Plant oils
- Oil-soluble botanical extracts
- Fat-soluble antioxidants
- Emollience
- Reducing water loss
- Supporting the skin’s lipid environment
- Richer, longer-lasting textures
The best formulation is therefore not necessarily the one that contains the most expensive or fashionable ingredients.
It is the one that matches the delivery system to the chemistry of those ingredients.
But what happens when we add waxes and butters?
This is where formulation becomes particularly interesting.
Waxes and butters are frequently added to natural skincare because they provide structure, consistency, richness and occlusivity.
Think about ingredients such as:
- Shea butter
- Cocoa butter
- Beeswax
- Candelilla wax
- Carnauba wax
They can transform a liquid oil into a balm or solid formulation.
But they also change the physical structure of the product.
And that can affect how ingredients are released.
Does wax prevent active ingredients from penetrating?
Not necessarily.
It is too simplistic to say that waxes “block” penetration.
What they can do is alter the release characteristics of the formulation.
Imagine an active ingredient trapped within a highly structured matrix.
Before that ingredient can interact with the skin, it first has to become available at the formulation/skin interface.
The process can be thought of as:
Formulation → release → skin surface → partitioning → diffusion through skin
If the active has a strong affinity for the formulation, it may remain relatively comfortable within that formulation instead of readily moving into the skin.
A highly structured wax-rich system can also reduce molecular mobility.
The result may be slower release.
But slower release isn’t necessarily a disadvantage.
A product that remains on the skin for a prolonged period can provide a sustained reservoir of ingredients rather than releasing everything rapidly.
The fascinating paradox of occlusion
There is another side to this story.
Waxes and butters can increase occlusion.
Occlusion reduces water loss.
Reduced water loss means greater hydration of the stratum corneum.
And hydration can influence the permeability of the outer skin barrier.
So we can potentially have two opposing effects occurring at the same time:
Effect 1
More wax/butter → stronger formulation structure → potentially slower release
Effect 2
More occlusion → reduced TEWL → increased skin hydration → potentially altered permeability
This is why it is impossible to look at a list of ingredients and simply conclude:
“This product will penetrate deeply.”
Real formulation science is considerably more complicated.
The importance of partitioning
One of the most important concepts in cosmetic delivery is partitioning.
For an ingredient to move from a formulation into the skin, it needs to have an appropriate affinity for both environments.
If it is extremely comfortable in the formulation, it may not have much driving force to leave it.
Conversely, if it has relatively low affinity for the formulation but an appropriate affinity for the skin, release may be more favourable.
This is one reason cosmetic formulators consider parameters such as lipophilicity and partition coefficient when developing delivery systems.
The formulation isn’t just a container.
It is part of the delivery mechanism.
So which is better: water or oil?
There isn’t a universal winner.
It depends on what you are trying to deliver.
A water-based gel containing aloe vera, flax seed mucilage and hyaluronic acid has a fundamentally different delivery system from an anhydrous facial oil containing jojoba, borage or raspberry seed oil.
And that’s precisely the point.
A good formulation isn’t about making every product penetrate as deeply as possible.
In fact, deeper isn’t automatically better.
For many cosmetic ingredients, the desired effect is at or within the epidermis rather than deep within living tissue.
The goal should be to make the ingredient available at the appropriate site, at an appropriate concentration, for an appropriate period of time.
This is where natural formulation gets particularly interesting
There is sometimes an assumption that natural skincare is simply a matter of replacing synthetic ingredients with plant-derived alternatives.
Good natural formulation is much more sophisticated than that.
A formulator needs to understand:
- The chemistry of the active ingredients
- Their solubility
- Their stability
- Their affinity for water and oils
- Molecular size
- pH
- The formulation’s physical structure
- Release characteristics
- Skin hydration
- Occlusion
- The skin barrier
- Compatibility between ingredients
And then select the appropriate vehicle.
That might be a gel.
An emulsion.
A facial oil.
A balm.
A butter.
Or something considerably more sophisticated.
Why this matters when choosing skincare
The next time you see a skincare product advertised as containing a long list of wonderful natural ingredients, ask yourself a different question.
Not just:
“What’s in it?”
But:
“How have those ingredients been formulated?”
Because putting an active ingredient into a product doesn’t automatically mean that the skin will receive it in the same way.
The formulation determines much of what happens next.
And this is perhaps one of the most overlooked aspects of skincare:
The ingredients matter.
But the delivery system matters too.
Good skincare formulation is ultimately about bringing those two things together.
The right ingredient.
The right concentration.
The right vehicle.
The right skin environment.
That’s where the science of skincare really begins.
~
Important Footnote: I would like to add, as a footnote to this article, that much of the driving force behind social media posts "knocking" water-based formulations comes from small and micro independent brands to justify why their own products only contain oils, butters and waxes. Many of the founder formulators behind these brands are not formally trained in skincare formulation and production and, as a result, don't have the necessary skills to handle emulsification (suspending plant oils in water or vice versa), which is a pre-requisite if you are to create water-based formulations. It is a way of covering for their own inexperience and shortcomings in skincare formulation, and putting positive spin on their range limitations. Next time you see one of these posts, check out the background to see if any of the products within the brand's offering are water-based....if not, make up your own mind about the validity of the post ;-)
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