The Quiet Superiority of Glycerin

Why the smallest humectant in cosmetic chemistry outperforms the most famous one, and why HONED chose it deliberately.

Hyaluronic acid has been the celebrity ingredient of the last decade. It appears on the front of every serum in every category, from twenty-dollar drugstore lines to five-hundred-dollar luxury creams. It is presented, almost universally, as the standard against which other hydrating ingredients are measured. Ask most people to name a moisturising skincare ingredient and hyaluronic acid is likely the first one they will say.

There is a quieter, smaller, less glamorous ingredient that outperforms it on nearly every measurable dimension of hydration science. It is not new, it is not proprietary, and it is not marketed with the same intensity. It is glycerin. And when we built the water-based serums at the heart of HONED — Hero and Structure — glycerin is what we chose to hydrate with.

This is the science behind that choice.

Both are humectants — and that is where the similarity ends

A humectant is an ingredient that attracts and binds water. Glycerin and hyaluronic acid are both humectants. In peer-reviewed cosmetic dermatology, they sit in the same functional category alongside urea, lactic acid, sodium PCA, panthenol, and butylene glycol. That shared category is what makes the comparison worth making — and what makes the differences within it so meaningful.

Because humectants are not interchangeable. Their molecular size, their penetration depth, the biological pathways they engage, and their behaviour across different environmental conditions all vary considerably. A 2016 review published in Indian Journal of Dermatology stated it plainly: "Trihydroxylated molecule glycerol is the most effective humectant." That is not a marketing sentence. It is the sober conclusion of a comprehensive academic review.

To understand why, the place to begin is not with what these ingredients do — but with how large they are.

The molecular size problem

Glycerin weighs approximately 92 daltons. This is small. Very small. For comparison: niacinamide is 122 daltons, retinol is 286 daltons, and the palmitoyl peptides used in HONED's Structure Serum range from approximately 578 to 932 daltons.

Hyaluronic acid, by contrast, is enormous. It exists across a wide range of molecular weights depending on formulation, but the most commonly used forms sit at approximately 1.8 million daltons — nearly twenty thousand times larger than glycerin. Low-molecular-weight hyaluronic acid, formulated to penetrate more effectively, still starts at around 50,000 daltons. The range is wide, and it is worth being precise: at any point on that range, hyaluronic acid remains considerably larger than glycerin.

The relevance of this is the 500 Dalton Rule — the principle in cosmetic chemistry which states that a molecule must weigh less than 500 daltons to passively penetrate the outer layer of the skin. We have written about this rule at length elsewhere, in the context of how HONED engineered peptide delivery in Structure Serum. It applies here as well.

Glycerin, at 92 daltons, comfortably penetrates the stratum corneum and works within the upper epidermis. Hyaluronic acid, at any of its commonly formulated molecular weights, does not. High-molecular-weight hyaluronic acid — the version in most of the products you have seen advertised — sits on the surface of the skin, forming a moisture-retaining film. It looks and feels hydrating in the moment. It does not penetrate.

This is the foundational difference. Glycerin gets in. Hyaluronic acid, for the most part, does not.

What glycerin does once it is inside

Small size gets glycerin through the barrier. It is what glycerin does after it arrives that makes it distinct.

Three mechanisms matter, and they are worth understanding individually.

Aquaporin-3 upregulation. Aquaporin-3 (AQP3) is a class of protein channels embedded in skin cell membranes that regulate the movement of water and glycerol through skin tissue. They are, in effect, the plumbing of the epidermis. Glycerin has been shown to upregulate these channels — to increase their activity and, over time, their expression. Rather than sitting on the skin surface and pulling water toward it, glycerin actively supports the skin's own internal water-transport infrastructure. In the aquaporin-3-deficient mouse model, topical glycerol has been shown to correct skin hydration, elasticity, and barrier function that were otherwise defective. This is a mechanism of action considerably deeper than the passive water-attraction that most humectants provide.

Natural moisturising factor support. The skin's natural moisturising factor, or NMF, is a mixture of water-soluble hygroscopic compounds — amino acids, lactic acid, pyrrolidone carboxylic acid, urea, and mineral salts — that naturally reside in the stratum corneum and keep it hydrated, flexible, and functional. NMF levels decline with age, with harsh cleansing, with sun exposure, and with the general accumulation of environmental insult. Glycerin supports and helps replenish the NMF, reinforcing the skin barrier from within rather than simply adding water at the surface. This is what makes it particularly valuable for skin that has been chronically dehydrated, barrier-compromised, or exposed to harsh conditions.

Corneocyte maturation. The 2016 review in Indian Journal of Dermatology describes glycerin's role in supporting the maturation of corneocytes — the cells that make up the outer layer of skin — by activating transglutaminase, facilitating desmosome digestion, and enabling healthy desquamation. In practical terms: glycerin helps immature, fragile skin cells mature into resilient ones, and helps the outermost dead cells shed properly rather than accumulating as dry, flaky patches. This is a functional depth that most humectants simply do not have.

Consistent performance across humidity

There is a final property of glycerin that deserves attention because it is rarely discussed and directly affects how the ingredient performs in real life.

Because glycerin engages the AQP3 system and integrates with the NMF rather than relying purely on drawing moisture from the air, it performs reliably regardless of environmental humidity. It works in a hot Sydney summer and in a heated Melbourne winter. It works in an air-conditioned office and on a dry-cabin flight. It works in a Byron Bay bathroom in July and a Toorak bathroom in January.

Hyaluronic acid does not have this consistency. High-molecular-weight hyaluronic acid draws water most effectively from a humid environment. When applied in very low-humidity conditions — dry climates, aeroplane cabins, centrally heated indoor spaces — hyaluronic acid on dry skin without a subsequent occlusive can draw water from the skin's own deeper layers rather than from the surrounding air. This can paradoxically leave the surface drier than it was before application. This is not a reason to avoid hyaluronic acid. It is a reason to understand it. But it is also a reason why we, as formulators, do not consider it the default first-line humectant it is often presented to be.

Head-to-head, in clinical trial

A 2016 study published in Skin Pharmacology and Physiology directly compared the hydrating performance of several common humectants — glycerin, hyaluronic acid, lactic acid, glycolic acid, propylene glycol, sorbitol, and urea — in a controlled head-to-head trial.

Glycerin outperformed all of them in increasing hydration levels in the stratum corneum.

This is the most robust multi-ingredient humectant comparison in the published literature. It does not receive the marketing coverage that a single flattering hyaluronic acid study receives, because glycerin does not have a brand campaign behind it. But the finding is available to anyone who cares to look.

We would not stake HONED's claim on this study alone. We stake it on the convergence of the molecular-size case, the mechanism-of-action case, the humidity-performance case, and the clinical-comparison case. Each of these is defensible individually. Together, they form a coherent argument that has shaped how we formulate.

What hyaluronic acid does well

We want to be careful here, because the point of this piece is not to dismiss hyaluronic acid — it is to explain why HONED made a different choice.

Hyaluronic acid has genuine strengths. Its water-holding capacity is exceptional; a molecule can bind up to 1,000 times its weight in water. It delivers an immediate, visible plumping effect at the skin surface. At very low molecular weights, it has been shown in research to support collagen synthesis in a way that gives it a mild anti-ageing dimension distinct from simple hydration. And it is one of the most skin-compatible ingredients in cosmetic science — genuinely gentle across sensitive, reactive, and pregnancy-safe conditions.

These are real properties, and they are why hyaluronic acid remains one of the most widely used ingredients in the industry.

A common framework within skincare guidance recommends using both ingredients in a single routine — hyaluronic acid on damp skin for immediate surface plumping, followed by a glycerin-containing moisturiser to deliver depth and seal it in. That is a reasonable approach for a diverse skincare wardrobe.

HONED is built on the discipline of the intelligent edit. Every active earns its place by over-delivering on the specific work it does, not by adding a light contribution to a stack of twelve products. We build three serums. And when a formulator is choosing which single humectant to include in a considered, minimalist formulation, glycerin does more of the work more of the time in more of the conditions the customer will actually encounter.

Where glycerin lives in HONED

Both of HONED's water-based serums — Hero and Structure — are built on glycerin.

In the Hero Serum, our 10% Niacinamide formulation, glycerin sits at position three on the INCI list: after water and niacinamide, before the pineapple extract, the botanical oils, and the preservative system. This is not a supporting cast placement. Under Australian cosmetic labelling conventions, INCI order reflects concentration in descending order. Glycerin is a major component of the formula.

In the Structure Serum, our peptide-based formulation, glycerin sits at position two on the INCI list: after water and before all three of the palmitoyl peptides that give Structure its clinical intent. Both glycerin and the peptide complex are formulated at their clinically effective concentrations — glycerin at the humectant-active range that meaningfully supports barrier hydration, the palmitoyl peptides at the science-backed percentages at which their collagen-signalling activity happens. As with most peptide actives, the peptides work at lower concentrations than humectants because that is where their signalling activity is most effective. The formulation is balanced with deliberate intent. The peptides do the collagen-signalling work. Glycerin does the barrier-hydration work that supports every other active in the formula and, over time, the skin's own regenerative processes. Neither active is a supporting ingredient; both are present at percentages that produce real skin outcomes.

Neither Hero nor Structure contains hyaluronic acid. Nowhere on our INCI lists will you find sodium hyaluronate or any of its salt derivatives. This is not oversight. It is design.

What this means for you

If you have been told, by every serum brand you have encountered over the last decade, that hyaluronic acid is the ingredient your skin needs — the science, on close inspection, does not entirely support that framing. Hyaluronic acid does one thing well: it plumps the surface, immediately and visibly. Glycerin does several things well: it penetrates, it engages the skin's own water-transport machinery, it supports the natural moisturising factor from within, and it performs reliably in any climate you happen to be in.

For a customer building a minimal, considered routine — someone using three serums instead of twelve — the ingredient choice matters more than it does in a stacked, layered regimen. In an over-stacked routine, a weak humectant can be compensated for by others. In a considered routine, every ingredient has to earn its place.

Glycerin earns its place in Hero and Structure by doing more work per molecule than the alternative.

Look like yourself on your very best day — confident, not corrected. That outcome depends on skin that is hydrated at depth, not just plumped at the surface. It depends on ingredients that penetrate rather than sit. It depends, quietly, on the smallest humectant in cosmetic chemistry doing more work than the loudest one.

The Hero Serum
The Structure Serum
The Edit

Frequently asked questions

Is glycerin actually better than hyaluronic acid? Glycerin is smaller, penetrates the stratum corneum more effectively, engages biological mechanisms hyaluronic acid does not, and performs more consistently across humidity conditions. A 2016 clinical study published in Skin Pharmacology and Physiology found glycerin outperformed hyaluronic acid and five other humectants in increasing stratum corneum hydration. On these specific measures, glycerin performs better. Hyaluronic acid has its own genuine strengths — particularly for immediate surface plumping and, at low molecular weights, mild collagen support — but it does not do the same functional work that glycerin does.

What is the 500 Dalton Rule and how does it apply here? The 500 Dalton Rule, first published by Bos and Meinardi in Experimental Dermatology in 2000, is the principle that a molecule must weigh less than 500 daltons to passively penetrate the outer layer of the skin. Glycerin at 92 daltons comfortably meets this threshold. Hyaluronic acid, at commonly formulated weights ranging from 50,000 to over 1.8 million daltons, does not.

What is aquaporin-3? Aquaporin-3, or AQP3, is a class of protein channels in skin cell membranes that regulate the movement of water and glycerol through skin tissue. Glycerin has been shown to upregulate these channels, actively supporting the skin's own water-transport infrastructure rather than simply attracting water passively at the surface.

Does HONED use hyaluronic acid in any of its products? No. Neither the Hero Serum, the Structure Serum, nor the R&R Serum contains hyaluronic acid or sodium hyaluronate. Our Hero and Structure formulations are built on glycerin as the primary humectant, supported by botanical actives and, in the case of Structure, palmitoyl peptides for collagen support.

Can I use hyaluronic acid alongside HONED? Yes. Nothing in HONED's formulation conflicts with hyaluronic acid, and there is no reason to remove a hyaluronic acid product from your routine if it works for you. HONED serums are designed to integrate smoothly alongside prescription dermatological actives and other well-formulated hydrating products.

Why does the skincare industry focus so heavily on hyaluronic acid if glycerin is more effective? Hyaluronic acid produces immediate, visible surface plumping that is easy to feel and easy to market. Glycerin's benefits are quieter — deeper penetration, mechanism-of-action support, consistent performance — and are harder to translate into a one-minute demonstration on social media. Marketing preference does not always follow the scientific evidence.

Is glycerin safe during pregnancy? Yes. Glycerin is considered pregnancy-safe and is one of the most skin-compatible ingredients in cosmetic science. Both Hero and Structure are formulated to be safe during pregnancy and breastfeeding.

Sources & further reading:

• Fluhr JW, Darlenski R, Surber C (2008). Glycerol and the skin: holistic approach to its origin and functions. British Journal of Dermatology 159: 23–34.
• Hara M, Verkman AS (2003). Glycerol replacement corrects defective skin hydration, elasticity and barrier function in aquaporin-3-deficient mice. Proceedings of the National Academy of Sciences 100(12): 7360–7365.
• Sethi A, Kaur T, Malhotra SK, Gambhir ML (2016). Moisturizers: The Slippery Road. Indian Journal of Dermatology 61(3): 279–287.
• Milani M, Sparavigna A (2017). The 24-hour skin hydration and barrier function effects of a hyaluronic 1%, glycerin 5%, and Centella asiatica stem cells extract moisturizing fluid. Clinical, Cosmetic and Investigational Dermatology 10: 311–315.
• Bos JD, Meinardi MMHM (2000). The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Experimental Dermatology 9: 165–169.
• HONED Hero Serum (10NIAC) PIF Rev 1.0, 10 April 2026.
• HONED Structure Serum (AAPS) PIF Rev 1.0, 10 April 2026.