Glucam™ P-20 – Fixative, Humectant, Solubilizer
Glucam™ P-20 by Lubrizol – The Complete Reference
Glucam™ P-20 is odorless, and that is its purpose. It does not change a composition – it changes its evaporation: it slows down the top notes, takes the sharpness out of the alcohol and keeps fragrance materials in solution where nothing else works anymore.
This reference explains what a fixative actually is, why a solvent is not one, and what a 1979 patent already knew about it.
Contents
- What is Glucam™ P-20?
- A Solvent Is Not a Fixative
- How a Physical Fixative Works
- The 1979 Patent
- What the Tests Showed – and What They're Worth
- Less Fragrance Oil for the Same Effect
- The Alcohol Sharpness
- Dosage
- The Other Functions
- The Molecule: A Sugar with Four Arms
- The Glucam Family
- Natural Origin Content: The Number Behind "Plant-Derived"
- The Microplastics Regulation
- Quick Reference: Data and Safety
- Further Questions
1. What is Glucam™ P-20?
Glucam™ P-20 (INCI: PPG-20 Methyl Glucose Ether, CAS 61849-72-7) is a propoxylated methyl glucose ether: a sugar backbone from corn starch onto which polypropylene glycol chains have been built. The material is 100% active, light-colored, distinctly viscous and practically odorless.
Its most unusual property comes first in the manufacturer's documentation: it is equally miscible with water, alcohols, organic esters and oils. Among liquid carriers, this combination is rare – most are at home either on the water side or the oil side, not both.
In the European COSING database (Ref. 79948), four functions are listed: Emollient, Hair Conditioning, Humectant, Skin Conditioning. The most interesting one for perfumery – fixation – is not listed there, because COSING records cosmetic, not perfumery functions.
2. A Solvent Is Not a Fixative
This is the most common misconception on the subject, and it costs beginners a lot of time.
Anyone who notices that their top note has vanished after ten minutes usually reaches for DPG, benzyl benzoate or isopropyl myristate – low-volatility liquids said to "fix". The effect fails to appear, and nobody explains why.
The patent underlying this class of materials says it in one sentence. Of ethyl phthalate and benzyl benzoate it states that they do little to enhance and prolong the fragrance – they are useful as low-volatility solvents for a broad range of fragrance materials.
The difference:
- A solvent extends and carries a formula. It dilutes, makes dosable, transports. It changes little about the evaporation behavior of the light components.
- A fixative intervenes in exactly this evaporation behavior.
Both are useful, both belong in a formula – but they do not replace each other.
And the second confusion
The word "fixative" also means two different things:
Olfactory fixatives have an odor of their own. Amber, musk and balsamic materials, absolutes, resinoids, classically also animal secretions. They fix by filling the ground onto which the composition settles as it evaporates. They work – but they bring their own odor with them.
Physical fixatives have no odor. They shift evaporation without touching the character. That was exactly the claim with which Glucam™ P-20 was patented at the time: known fixatives could distort the nature or character of the fixed fragrance, and this problem was solved by essentially odorless methyl glucoside polyols – tenacity increases without distortion.
3. How a Physical Fixative Works
The industry-standard definition: a fixative serves to equalize the vapor pressures and volatilities of the raw materials in a perfume oil composition and to increase odor tenacity.
The mechanism behind it: how quickly a component escapes from a mixture depends not only on its own vapor pressure but also on what it is dissolved in. A very high-boiling, non-volatile component raises the boiling point of the entire composition and holds back the light molecules for longer.
Two numbers show how large the gap is. Glucam™ P-20 boils above 316 °C; the citrus terpenes at the heart of the top-note problem boil in the range of around 175 °C. Between them lies an order of magnitude in volatility.
The problem being addressed is familiar to anyone who formulates: the composition opens well, and after ten minutes a gap opens up until the heart takes over. The progression breaks off instead of carrying through.
4. The 1979 Patent
The use of alkoxylated methyl glucosides as fragrance fixatives is documented – and unusually thoroughly for a material hardly anyone writes about today.
US 4,264,478 "Polyol fragrance fixatives", filed on December 26, 1979 as a continuation of an application of October 30, 1978, granted on April 28, 1981. In addition, the divisional application US 4,324,703 on the composition, granted in 1982.
The text names the material: methyl glucoside polyols are commercially available from Amerchol Corporation, Talmadge Road, Edison, New Jersey, under the trademark GLUCAM. E-10 and E-20 are the 10- and 20-mole ethoxylates, P-10 and P-20 the corresponding propoxylates.
The patent names three advantages that set it apart from known fixatives:
- No odor of its own, hence no distortion of the fragrance
- Soluble in water, alcohol and hydroalcoholic systems – whereas most fixatives of the prior art at the time were insoluble in water
- Lower fragrance requirement for the same impression
The breadth of application claimed even then is also interesting: perfume, cologne, after-bath splash, aftershave, perfumed powders, soaps, creams, lotions – and, curiously enough, perfumed p-dichlorobenzene, i.e. scented blocks.
5. What the Tests Showed – and What They're Worth
The patent contains panel comparisons across nine product types. In each case two identical batches, one with and one without the additive.
| Product | Additive | on skin | on blotter |
|---|---|---|---|
| Perfume | 2.5% P-20 | 97% | 94% |
| Eau de Toilette | P-20 | 95% | 89% |
| Cologne | P-20 | 93% | 86% |
| After-bath splash | P-20 | 93% | 90% |
| Aftershave | E-10 | 89% | 84% |
| Powder | P-10 | 86% | – |
| Hand cream | E-20 | 82% | – |
| Bar soap | P-20 | 94% (intensity) | |
| Scented blocks | P-20 | 87% (intensity) | |
The percentages indicate how many participants noticed longer tenacity in the batch with the additive. For the perfume, observation ran over one to ninety-six hours.
How reliable is this?
We think it's right to say this openly: these are the applicant's own panels from the time of filing, i.e. 1978/79. The number of participants is not stated anywhere, the methodology is described in one sentence each. By today's standards this is not a study but an application test as part of a patent filing.
In one of the examples the patent text also contains an obvious arithmetic error: "43% considered B stronger, the remaining 75% considered both equal" – a total of 118%.
So the numbers show a direction; they do not measure it. Nevertheless, it remains the most reliable publicly available source on this material – everything stated about dosages on retailer pages today ultimately traces back to it.
6. Less Fragrance Oil for the Same Effect
A side finding that appears hardly anywhere and is practically useful when formulating.
The patent puts it this way: products with methyl glucoside polyols do not require as high a concentration of fragrance materials as comparable products without them.
This is supported by three batches with reduced oil content:
- Perfume: 71.5% of participants rated the reduced version with P-20 as equal or better
- Cologne: 85.7% as equal or better
- Splash: the majority saw no difference
Read practically, this means: if a composition feels too dense, the concentrate share can be lowered and the perceived strength regained via the fixative. The formula becomes more transparent without becoming quieter.
7. The Alcohol Sharpness
Two effects need to be distinguished here that are often lumped together.
Sharpness in the nose
The cleanest experiment in the entire patent. Denatured alcohol was mixed with increasing amounts of P-20; participants smelled from bottles with 12 and 25 mm openings and assessed the solvent sharpness.
| P-20 content | Share of participants who preferred the treated sample |
|---|---|
| 0.5% | 67% |
| 1.0% | 83% |
| 2.0% | 100% |
This is the only point at which a dose-response relationship becomes visible – at 2% the effect was clear to all participants.
Burning on the skin
A different effect, backed by a different source: the manufacturer today states that in alcoholic systems Glucam™ P-20 reduces the burning that alcohol causes on the skin.
An Eau de Parfum consists of 70–85% ethanol. On freshly shaved skin or in winter this is noticeable. A hygroscopic polyether holds moisture in the stratum corneum and mitigates the effect.
8. Dosage
The patent's figures refer to the alcoholic, aqueous or hydroalcoholic portion of the composition – not to the overall formula. For an Eau de Parfum the difference is small, for oily systems considerable.
| Goal | Share |
|---|---|
| Fragrance fixation, overall range | 0.5–5% |
| Preferred range | 1.0–2.5% |
| Skin feel and spreadability | 2–15% |
On the upper range the patent makes a separate remark: there, the material replaces other polyols in the system – glycerin, sorbitol or propylene glycol – while also providing the fixation that these traditional polyols do not deliver.
That is a use case of its own: glycerin is often added to alcoholic fragrance waters "for the feel" and is sticky. Here you get the same feel without stickiness – and tenacity on top.
How to test the effect honestly
Prepare two identical batches, one with 1.5%, the other with nothing. Compare after twenty minutes and after two hours. The difference shows exactly at the transition from top to heart note – not in the first minute.
9. The Other Functions
Fixation is the perfumery role. But the material is primarily sold for other purposes.
Humectant
The defining function – humectant is in the product name. The sugar backbone binds water. The manufacturer describes the result as moisture retention with a gliding, emollient feel.
The difference from glycerin lies exactly there: glycerin also binds water, but is sticky and can draw moisture out of the skin at low humidity. A branched polyether is not sticky.
Emollient and lubricant
Smooths and softens – without the greasy film of oily emollients, because the material is water-soluble.
Hair care
In shampoos, conditioners and styling products: holds moisture in the hair, improves combability. A main area of application for the material.
Solubilizer
The second most important role for perfumery. PPG methyl glucose ethers are listed among coupling agents – materials that stabilize emulsions and act as clarifiers.
The difference in terms: solubilizers and coupling agents essentially do the same thing, with "coupling agent" usually referring to materials that produce a true solution rather than a micellar haze.
In practice this means: hydroalcoholic systems with reduced alcohol content and alcohol-free fragrance waters become formulable in the first place.
Soap
Keeps the bar moist and smooth, prevents cracking, makes application easier. Usable over a pH range of 3 to 10. Plus the finding from the patent: 94% of participants perceived the fragrance in the treated soap bar as more intense.
The relative: Glucam™ P-20 Distearate
The same backbone, esterified with stearic acid at the ends. Thus no longer a humectant but an emollient – and with a natural origin content of 36.9% instead of 12%, because the plant-based stearic residues bring additional natural carbon. A good example of how strongly one and the same backbone is steered via its end groups.
10. The Molecule: A Sugar with Four Arms
Methyl glucoside is the simplest derivative of glucose: a glucose molecule whose anomeric hydroxyl group has been replaced by a methoxy group. It is obtained by the Fischer method, heating starch or glucose with methanol under acid catalysis. The starting material is corn starch.
The patent describes the result precisely: a mixture of alpha- and beta-methyl glucoside forms in a ratio of about 2:1; the molecule is in the pyranoside form and is a cyclic, "internal" full acetal.
Four free hydroxyl groups remain on the ring. They are the growth points. And they are not equivalent: the primary hydroxyl group at C6 reacts preferentially, followed by the group next to the methoxy group at C2.
Propylene oxide is built onto them – twenty units in total, distributed over the four arms, i.e. around five per arm. In CAS nomenclature this ratio is recorded as (4:1).
The reaction itself runs with an alkaline catalyst, typically potassium hydroxide, at 140–160 °C. Since propylene oxide boils below this temperature, the process runs in a closed vessel under pressure; the catalyst is then neutralized with acid.
Everything else follows from this design:
- The sugar center attracts water – hence the hygroscopicity
- The polypropylene arms bring affinity to oils and alcohols
- Together, this produces the unusual miscibility in both directions
- The branching explains why the material is viscous but not sticky: it doesn't form strings
11. The Glucam Family
Methyl glucoside chemistry for cosmetics does not come from Lubrizol, but from Amerchol – an American house that historically also stood for lanolin derivatives.
In 2003 Lubrizol acquired from Amerchol, then a subsidiary of Dow Chemical, a selected part of its personal care ingredients business – annual sales of around 30 million US dollars. Included were methyl glucoside derivatives, lanolin derivatives and the Promulgen emulsifiers. In 2005 the division was transferred into the Noveon Personal Care unit.
As a result, a whole family built on the same sugar core remains under one roof to this day:
| Line | Function |
|---|---|
| Glucam | Humectants and carriers |
| Glucamate | Thickeners |
| Glucate | Emulsifiers |
| Glucquat | Conditioning agents |
One basic building block, four classes of substances – the difference lies solely in what is attached to the four hydroxyl groups.
E versus P
Within the Glucam line there are two series, depending on which epoxide was used.
| Glucam E | Glucam P | |
|---|---|---|
| Epoxide | Ethylene oxide | Propylene oxide |
| INCI | Methyl Gluceth-10/-20 | PPG-10/-20 Methyl Glucose Ether |
| Character | more hydrophilic | more lipophilic |
| Skin feel | light, satiny | gliding, emollient |
| Miscibility with oils | limited | good |
The number indicates the number of epoxide units. For perfumery the P series is the relevant one: the lateral methyl group of propylene oxide is exactly what creates compatibility with alcohol and with fragrance esters.
12. Natural Origin Content: The Number Behind "Plant-Derived"
The manufacturer describes the material as naturally derived. Formally that is correct – the core comes from corn starch.
But the same company also publishes the assessment according to ISO 16128, and for Glucam™ P-20 it reads:
- RCI (Renewable Carbon Index): 0.09
- NOC (Natural Origin Content): 12.0%
Under the same standard, "natural" means an RCI of 1.00, "naturally derived" an RCI above 0.50. Glucam™ P-20 falls into neither category.
The reason is pure arithmetic: the methyl glucoside contributes seven carbon atoms, the twenty propylene oxide units sixty. The sugar core is less than a tenth of the carbon skeleton.
Compared within the same manufacturer table:
| Material | RCI | NOC |
|---|---|---|
| Glucam P-10 | 0.16 | 21.1% |
| Glucam P-20 | 0.09 | 12.0% |
| Glucam E-20 | 0.13 | 15.2% |
| Glucam P-20 Distearate | 0.41 | 36.9% |
| Glucate DO (emulsifier) | 0.98 | 95.7% |
The rule can be read off: the longer the polyether arms, the lower the natural content. P-10 is twice as "natural" as P-20, simply because the arms are shorter.
We state the number because "plant-derived" would be misleading without it. Anyone who reads INCI lists knows anyway that PPG-20 stands for twenty propylene oxide units.
13. The Microplastics Regulation
Since Regulation (EU) 2023/2055 entered into force on October 17, 2023, the word "polymer" in an INCI list regularly triggers questions. Hence the classification here.
The regulation defines microparticles as particles containing solid polymer, where at least 1% by weight of the particles either measure no more than 5 mm in all dimensions or are no more than 15 mm long with a length-to-diameter ratio above 3.
Expressly not covered are:
- naturally occurring, chemically unmodified polymers
- polymers with a solubility above 2 g/l
- (bio)degradable polymers
- non-carbon-based polymers
The manufacturer has published its own statement listing its liquid polymers that fall outside the scope – Glucam™ P-20 is on this list.
The reasoning is straightforward: the restriction targets solid microparticles with defined physical limits. Glucam™ P-20 is supplied as a liquid and remains liquid in formulations – there are no particles. Added to this is its water solubility, which on its own already takes it out of the definition.
14. Quick Reference: Data and Safety
| Manufacturer | Lubrizol Advanced Materials |
| INCI | PPG-20 Methyl Glucose Ether |
| CAS No. | 61849-72-7 |
| COSING Ref. | 79948 |
| Active content | 100% |
| Appearance | Liquid, yellow |
| Odor | Very faint |
| pH (100%) | 5–8 |
| Relative density (20 °C) | 1.1 |
| Boiling point | > 316 °C |
| Flash point | 263 °C (Cleveland open cup) |
| Decomposition temperature | 300 °C |
| Water solubility | Soluble |
| Natural origin content (ISO 16128) | 12% (RCI 0.09) |
| CLP classification | Not classified |
| Transport | Not regulated as dangerous goods |
Safety. Under GHS/CLP the material is not classified as hazardous – no pictogram, no signal word, no H statements.
In 2016 the Cosmetic Ingredient Review presented a final assessment of 25 methyl glucose polyethers and esters, PPG-20 Methyl Glucose Ether included, concluding that they are safe in the present practices of use and concentration. They are neither genotoxic nor toxic to reproduction or development; owing to their high water solubility they are absorbed only slowly through the skin, reach low blood concentrations and are rapidly excreted renally. Use concentrations in cosmetics of up to 15% are reported there.
One point on which sources differ. According to the manufacturer's data, eye irritation is assessed by read-across as "not irritating". The CIR assessment, on the other hand, lists a Draize test on the material itself in 100% form, classified there as a mild, transient irritant. The difference is small, but it concerns exactly the form in which the material is supplied: undiluted. Eye protection is part of handling the concentrate.
Environment. Ecotoxicologically unremarkable – LC50 fish and EC50 Daphnia each above 10,000 mg/l. The material is not readily biodegradable (34% in 20 days).
Purity. No antioxidants, no preservatives added. None of the 26 declarable fragrance allergens to be expected. No VOC content.
Storage. The only condition expressly named to avoid is frost. Incompatible with strong oxidizing agents.
Further Questions
Why does my top note vanish after ten minutes?
Because citrus and aldehydic notes have a vapor pressure orders of magnitude higher than the rest of the formula. They evaporate first, and a gap opens between them and the heart. A physical fixative lowers the volatility of the light components and straightens the progression.
I added DPG and it did nothing. Why?
Because DPG is a solvent, not a fixative. It dilutes and carries, it makes dosable – but it hardly intervenes in the evaporation of the light components. The same applies to benzyl benzoate and isopropyl myristate. The 1979 patent already states exactly this.
Does Glucam™ P-20 have an odor?
Practically not. According to the manufacturer's data, it has a very faint odor of its own; at 1–2% none of it is perceptible in the finished perfume. Its usefulness rests on exactly that – a fixative that smells itself shifts the character of the composition.
How high should it be dosed?
Preferably 1.0–2.5%, relative to the alcoholic or aqueous portion. The overall range is 0.5–5%. For skin feel and spreadability 2–15% is possible – in this range the material replaces glycerin or propylene glycol.
Can I replace glycerin with it?
In alcoholic and hydroalcoholic fragrance products, yes. The patent expressly names glycerin, sorbitol and propylene glycol as the polyols that can be replaced – adding that fixation, which these polyols don't offer, comes along with it. In creams the situation is different; there, glycerin fulfills other tasks.
Does it also work in oil-based perfumes?
The material is miscible with oils, but the documented dosages refer to the alcoholic or aqueous portion of a formula. There is no reliable data for purely oily systems – only your own comparison batch helps here.
Is this a natural product?
No. The core comes from corn starch, the predominant part of the molecule from propoxylation. According to ISO 16128 the natural origin content is 12%.
Does it fall under the EU microplastics regulation?
According to the manufacturer, no. Regulation (EU) 2023/2055 covers solid synthetic polymer microparticles; Glucam™ P-20 is supplied as a liquid and remains liquid. In addition, it is water-soluble, which on its own already takes it out of scope.
What is the difference from Glucam™ E-20?
E-20 is ethoxylated instead of propoxylated and therefore more hydrophilic – good in aqueous systems, weaker in alcoholic-oily ones. For perfumery, the P series is the right fit.
Does the material need to be preserved?
No preservatives are added to the raw material; the total bacterial count is below 10 per gram. In water-containing final formulations, a preservation system remains a matter of the recipe as usual.