Curly hair products live or die on six ingredient functions: cleansing, conditioning, humectancy, emollience, film-forming, and preservation. The label on the back of the bottle tells you which job each molecule is doing — once you can read it. This glossary teaches you to scan an INCI list in about sixty seconds, name every ingredient by its standardised chemical name rather than its marketing name, and decide whether a product belongs in your routine before you reach the checkout. It is built for label readers, not slogan believers.
How to Read an INCI List in 60 Seconds
INCI stands for International Nomenclature of Cosmetic Ingredients. It is the global standard that forces every cosmetic brand selling into the EU, UK, US and most other major markets to list ingredients by the same chemical names, in descending order of concentration, down to 1% — after which the order becomes optional and brands can re-shuffle. The list is also maintained as a searchable public database by the European Commission DG GROW, EU CosIng database (ec.europa.eu/growth/tools-databases/cosing/), which is the source of truth we use to verify names and definitions throughout this glossary.
Three rules will get you through any curly hair label in under a minute:
- The first five ingredients are the product. Water (Aqua) is almost always first. The next four tell you what the formula actually is — a cleanser if the second ingredient is a surfactant; a conditioner if it is a fatty alcohol or cationic surfactant; a styler if it is a film-former.
- Anything below 1% is sequenced for marketing. Honey, keratin or argan oil listed after the preservatives is at fractional-percent inclusion. It is real, but the dose is small.
- The preservative and fragrance system is at the bottom. This is normal and required. It is not a warning sign — a product without a preservative is a product with a five-day shelf life.
Once you have those three orientations, the rest of this article tells you what each function is for, which INCI names belong to it, and where build-up risk, water-solubility and porosity sit on each ingredient.
The Six Ingredient Functions That Matter
Almost every ingredient in a curly hair product belongs to one of six functional categories. The marketing copy on the front of the bottle ("hydrating," "defining," "frizz-control") is a claim; the function categories below are what the molecules actually do. Society of Cosmetic Chemists, Conditioning Agents for Hair and Skin (2nd ed., Routledge, 2017) is the textbook reference we work from for this taxonomy — it is the same framework that formulators use inside the cosmetic industry.
| Function | What it does | Where it sits on a typical label | Build-up risk |
|---|---|---|---|
| Cleanser (surfactant) | Removes oil, sweat, product residue | Top 3 in shampoo and co-wash | Low |
| Conditioning agent | Smooths cuticle, reduces friction | Top 5 in conditioner; top 10 in leave-in | Low to moderate |
| Humectant | Pulls water from the air into the hair | Top 5–8 in leave-in, cream, gel | Low |
| Emollient | Coats and softens the cuticle | Top 5–10 in cream, butter, oil | Moderate |
| Film-former | Holds the curl shape after drying | Top 5 in gel, mousse, custard | Moderate to high |
| Preservative | Stops the product from spoiling | Bottom 3–5 of the label | Low (functional, not optional) |
A well-built leave-in conditioner has all six. A well-built gel has five (no cleanser). A well-built shampoo has cleanser, light conditioning agent, and preservative as the core. If a product is missing one of its expected functions, it is either an unusual formula or a poorly built one — and the label will tell you which.
Cleansers — Sulfates, Sulfate Alternatives, Co-Wash Bases
A cleanser is a surfactant — a molecule with a water-loving end and an oil-loving end, which is what allows it to lift sebum and product residue off the hair shaft and rinse them away in the next wash cycle. Curly hair tolerates strong cleansing badly because the same surfactants that strip sebum also strip the lipid layer that keeps the cuticle smooth.
The full sulfate family. SLS (Sodium Lauryl Sulfate), SLES (Sodium Laureth Sulfate), Ammonium Lauryl Sulfate, and Ammonium Laureth Sulfate are the four you will see most often. They are anionic — negatively charged in solution — and very efficient. SLS is the strongest and most stripping; SLES is gentler because the ethoxylation step softens the charge density. Randy Schueller and Perry Romanowski, It's OK to Have Lead in Your Lipstick (Brain Pickings, 2011) make the point that the cosmetic-chemist consensus on sulfates is more nuanced than the curly internet's: sulfates are not unsafe; they are sometimes too efficient for the job. The distinction matters.
Gentle sulfate alternatives. Cocamidopropyl Betaine (a coco-derived amphoteric surfactant), Decyl Glucoside and Coco-Glucoside (sugar-derived non-ionics), Sodium Cocoyl Isethionate (a mild syndet) and Disodium Cocoyl Glutamate are the cleansers that have replaced sulfates in most curly-specific shampoos. They cleanse roughly 30–60% less aggressively than SLS and leave more of the natural lipid layer intact.
Co-wash bases. A co-wash is a "conditioning cleanser" — the surfactant is so mild that the formula resembles a thin conditioner. The INCI signature is Behentrimonium Methosulfate or Cetrimonium Chloride high in the list, with little or no anionic cleanser. Co-wash works for low-porosity, low-density curls that need very little de-greasing; it accumulates on high-porosity and high-density hair within two to three wash cycles. Read our sulfate-free shampoo guide for curly hair for which of these to pick in which water hardness.
Conditioning Agents — Cationic Surfactants and Humectants
Conditioning agents are the molecules that deposit on the hair shaft after the surfactants have rinsed away. The dominant family is the cationic surfactants — quaternary ammonium compounds, positively charged, which bind to the negatively-charged damaged sites on the cuticle and stay there even after rinsing. Society of Cosmetic Chemists, Conditioning Agents for Hair and Skin (2nd ed., Routledge, 2017) treats this as the single most important class of curly-hair-relevant ingredients, and the textbook is correct.
The cationics you will see most often:
| INCI name | What it is | Where it shines |
|---|---|---|
| Behentrimonium Methosulfate (BTMS) | Derived from rapeseed; mild, conditioning | Co-washes, deep conditioners, leave-ins |
| Cetrimonium Chloride | Quat with detangling power | Rinse-out conditioners, leave-ins |
| Cetrimonium Bromide | Stronger detangler | Targeted detangling sprays |
| Stearamidopropyl Dimethylamine | Cationic that activates at low pH | Protein-free conditioners |
The supporting cast — Cetyl Alcohol, Cetearyl Alcohol, Stearyl Alcohol — are fatty alcohols, not the drying alcohols we cover later. They are emollient conditioners that give a product its rich, slip-y texture and help curls feel soft rather than crisp. If a conditioner feels like cold whipped cream when you scoop it, fatty alcohols are why.
Humectants — Glycerin, Honey, Hyaluronic Acid, Sorbitol
A humectant is a molecule that holds water. In a curly hair product, the humectant pulls water from the surrounding air and from the product itself into the hair shaft. The catch is that humectants are dew-point sensitive: in very dry air (below about 30°F / -1°C dew point) the humectant pulls water out of the hair and into the room, which produces brittle, frizz-prone curls; in very humid air (above about 60°F / 16°C dew point), the same humectant pulls so much water in that the cuticle swells and frizz climbs again. Sister Scientist (Erica Douglas), "Hair Care: Glycerin & Dew Points" white paper (sisterscientist.com, 2019) is the reference paper on this, and we cite her directly in our glycerin and humectants explainer.
| INCI name | Marketing name | Strength | Build-up risk |
|---|---|---|---|
| Glycerin | Vegetable glycerin | High | Low |
| Mel | Honey | High | Low |
| Sodium Hyaluronate | Hyaluronic acid | Very high (mass-for-mass) | Low |
| Sorbitol | Sugar alcohol | Moderate | Low |
| Propanediol | Plant-derived | Moderate | Low |
| Panthenol | Provitamin B5 | Moderate (also a film-former) | Low |
For low-porosity hair, keep humectants in the top 5–8 ingredients of a leave-in but pair them with an emollient layer on top — otherwise the water you pull in evaporates faster than the cuticle can hold it. For high-porosity hair, humectants do their best work; they are part of why your hair drinks product so quickly.
Emollients — Oils, Butters, Esters
Emollients soften and coat the hair. Mechanically, they reduce friction between strands and smooth the cuticle's outer edge, which is what we perceive as "shine." Chemically, they range from light esters (which sit on the surface and barely penetrate) to medium-chain oils (which partially penetrate the cortex) to heavy butters (which form a layered film on top of the cuticle).
Penetrating oils — small enough to enter the cortex. Cocos Nucifera (Coconut) Oil, Olea Europaea (Olive) Fruit Oil, and Persea Gratissima (Avocado) Oil all penetrate the hair shaft to some extent and reduce protein loss from the cortex during wash cycles. Coconut oil has the best evidence here and the smallest molecular profile.
Sealing oils — sit on top of the cuticle. Simmondsia Chinensis (Jojoba) Seed Oil (technically a liquid wax ester), Argania Spinosa Kernel Oil, Ricinus Communis (Castor) Seed Oil, and Brassica Campestris (Rapeseed) Seed Oil. These three are the workhorses of high-porosity routines — they form a sealing layer that slows water loss. The full breakdown sits in our hair oils for curls guide.
Butters. Butyrospermum Parkii (Shea Butter), Theobroma Cacao (Cocoa) Seed Butter, Mangifera Indica (Mango) Seed Butter. Heavy emollients that need warmth and emulsification to spread evenly. They reward type 3C, 4A, 4B and 4C hair; they overwhelm fine type 2 and type 3A.
Esters — the under-discussed category. Caprylic/Capric Triglyceride (fractionated coconut), Isopropyl Myristate, and Cetearyl Olivate are synthetic or processed emollients that mimic the feel of natural oils with better stability and lower greasiness. They sit between oils and silicones on the slip spectrum and are increasingly used in modern leave-ins.
Film-Formers — Polyquaterniums, PVP, Carbomers
A film-former is a long-chain molecule that lays a thin transparent film over the hair as the water evaporates. The film holds the curl shape it dries into — without one, even the most defined wet curl falls into frizz as the strand straightens. Film-formers are what makes a gel a gel.
| INCI name | Family | Hold strength | Water-solubility |
|---|---|---|---|
| Polyquaternium-7 | Cationic film-former | Light to medium | Yes |
| Polyquaternium-10 | Cellulose-based | Light, conditioning | Yes |
| Polyquaternium-11 | Strong-hold cationic | Medium to high | Yes |
| PVP (Polyvinylpyrrolidone) | Vinyl polymer | Medium | Yes |
| VP/VA Copolymer | Vinyl/vinyl-acetate | Medium, humidity-resistant | Yes |
| Carbomer | Crosslinked polyacrylic | Light (structural gel base) | Yes |
| Acrylates Copolymer | Synthetic film | Strong, brittle if over-applied | Yes |
| Xanthan Gum | Natural polysaccharide | Soft, no real hold | Yes |
| Hydroxypropyl Guar | Plant-derived | Light to medium | Yes |
| Flax (Linum Usitatissimum) Seed Extract | Natural mucilage | Light, soft cast | Yes |
All of these are water-soluble, which is part of why they belong on this list. The hold-strength column corresponds roughly to the wet/dry feel: light formers produce no cast and minimal frizz protection; strong formers produce the "crunchy" gel cast that breaks under your fingers once dry. The choice between curl cream, gel and mousse is largely a choice between film-former concentrations.
Silicones — The Soluble vs Non-Soluble Question
Silicones are the most over-simplified ingredient class in the curly hair internet, and the simplification — avoid all silicones — is wrong. There are three categories, and they behave very differently.
Water-soluble silicones. Dimethicone Copolyol, PEG-8 Dimethicone, PEG-12 Dimethicone, Hydroxypropyl Polysiloxane, and Bis-PEG-18 Methyl Ether Dimethyl Silane. The "-PEG-" prefix is the tell. These rinse out with normal water and a mild surfactant. They are useful as light slip agents in leave-ins and detanglers.
Evaporating (volatile) silicones. Cyclomethicone, Cyclopentasiloxane, Cyclohexasiloxane. These coat the hair, deliver slip, and then evaporate within minutes — leaving no residue at all. Functionally they are the closest thing to a "free pass" in the silicone family. Several major markets have phased Cyclopentasiloxane out of rinse-off products on environmental grounds, but it remains permitted in leave-ons under EU CosIng.
Non-soluble silicones. Dimethicone, Amodimethicone, Phenyl Trimethicone, Trimethylsilylamodimethicone. These deliver dramatic slip and shine but require a stronger surfactant (a sulfate or a strong syndet) to fully rinse off. On low-porosity hair they accumulate visibly within two to three uses and produce dull, weighted, "coated" curls. On high-porosity, very damaged hair, the same coating can be a deliberate sealing strategy that buys weeks of less breakage while the cuticle repairs underneath.
The honest position — which sits at odds with most curly-internet copy — is that non-soluble silicones are a tool with a specific job, not a poison. We cover the full case in are silicones bad for curly hair.
Proteins — Hydrolysed Keratin, Wheat, Silk, Quinoa
Proteins fill in the temporary gaps in a damaged cuticle. They are hydrolysed — broken down into shorter peptide chains — so that they are small enough to attach to the hair surface and, in some cases, penetrate slightly into the cortex.
| INCI name | Source | Particle size | Best for porosity |
|---|---|---|---|
| Hydrolyzed Keratin | Sheep wool / synthetic | Medium | High porosity |
| Hydrolyzed Wheat Protein | Wheat | Small (3,000–5,000 Da) | Low to medium porosity |
| Hydrolyzed Silk | Silkworm | Very small (1,000–10,000 Da) | All porosities |
| Hydrolyzed Quinoa | Quinoa | Small | Low porosity, fine strands |
| Hydrolyzed Rice Protein | Rice | Small | Low to medium porosity |
| Hydrolyzed Soy Protein | Soybean | Medium | High porosity, coarse strands |
| Hydrolyzed Collagen | Bovine / marine | Large | Very high porosity only |
The smaller-particle proteins (silk, wheat, quinoa) are tolerated by almost everyone in the leave-in range. The larger-particle proteins (collagen, keratin) are powerful but risky on hair that doesn't need them — they can stiffen low-porosity hair into a brittle state inside a single application. The protein-balance principle, and how to tell whether you are over-proteined or under-proteined, sits in our dedicated protein treatments for curly hair guide.
Alcohols — Drying vs Fatty (the most confused category)
This is the category most readers get wrong, because "alcohol" reads as a single thing on a label when it is at least two different things in chemistry. Alcohols on an INCI list split into two functional groups: short-chain alcohols (drying solvents) and long-chain fatty alcohols (emollient conditioners).
Drying alcohols — the short-chain solvents. SD Alcohol 40, SD Alcohol 40-B, Alcohol Denat., Ethanol, Isopropyl Alcohol, Propanol. These evaporate quickly and pull water with them as they go, which is exactly the property mousse and hairspray formulas exploit (fast set, no wet feel). On already-dry, already-porous curls, the same evaporation strips cuticle moisture. The classic curly-hair-bad alcohols.
Fatty alcohols — the long-chain conditioners. Cetyl Alcohol, Cetearyl Alcohol, Stearyl Alcohol, Behenyl Alcohol, Myristyl Alcohol, Lauryl Alcohol. Solid or waxy at room temperature, with 12 to 22 carbons in the chain. These are emulsifiers and emollients — the texture-builders of every conditioner and cream you have ever used. They do not dry the hair. They do the opposite.
The shortcut: if the alcohol's INCI name is one or two short words ("Alcohol Denat.," "SD Alcohol 40"), treat it with care on dry curls. If it starts with cet-, cetear-, stear-, behen-, lauryl-, myristyl-, or arachidyl- it is a fatty alcohol and is doing conditioning work.
Preservatives — What's in There and Why
Preservatives stop the product from becoming a microbial farm in your shower. A leave-in with no preservative system is unsafe within five to ten days of opening. The major families:
- Parabens — Methylparaben, Ethylparaben, Propylparaben, Butylparaben. The most-studied preservative class in cosmetic history; permitted at low concentrations under EU regulation, with restrictions on Propyl- and Butyl- under EU Regulation 1223/2009.
- Phenoxyethanol — Glycol ether, permitted up to 1% in rinse-off and leave-on products under CosIng. Common modern replacement for parabens.
- Organic acids — Sodium Benzoate, Potassium Sorbate, Benzoic Acid, Sorbic Acid, Levulinic Acid. The "natural-leaning" preservative system; effective only below pH ~5.5.
- Isothiazolinones — Methylisothiazolinone (MIT), Methylchloroisothiazolinone (CMIT). Effective preservatives but high allergen rates; restricted in EU leave-on products since 2017.
- Formaldehyde donors — DMDM Hydantoin, Diazolidinyl Urea, Imidazolidinyl Urea. Effective; release formaldehyde at low concentrations over time. Permitted under regulation; some readers choose to avoid them on sensitivity grounds.
- Caprylyl Glycol / Ethylhexylglycerin — usually paired with another preservative as a booster.
A balanced preservative system is two or three of the above used together. Single-preservative formulas are either using an aggressive preservative or have a very short shelf life.
The Watchlist: Ingredients to Approach with Care
What ingredients should I avoid in curly hair products? Four high-risk categories cover almost every curly-hair "avoid" claim worth taking seriously: short-chain drying alcohols (Alcohol Denat., SD Alcohol 40, Ethanol, Isopropyl Alcohol) which strip moisture on already-dry curls; non-water-soluble silicones (Dimethicone, Amodimethicone, Phenyl Trimethicone, Trimethylsilylamodimethicone) which build up on low-porosity hair within two or three wash cycles; harsh anionic sulfates (Sodium Lauryl Sulfate, Ammonium Lauryl Sulfate) on dry, porous, or chemically-treated hair where the cleansing efficiency outruns what the strand can tolerate; and fragrance (Parfum / Fragrance) on sensitised scalps, where the undisclosed mix can contain over 200 individual aromatic compounds that act as contact-irritants for some readers.
Notice the conditional language. None of these are always bad; each becomes a problem on a specific hair state. That is the gap between this article and most "ingredients to avoid" listicles you will read elsewhere.
Are sulfates always bad? No. Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) are strong anionic cleansers — they are very effective at removing oil and product residue, and the same efficiency makes them stripping for hair that is already dry, porous, or coloured. Gentler alternatives such as Cocamidopropyl Betaine and Decyl Glucoside cleanse roughly 30–60% less aggressively and are the right default for most curly routines. A full sulfate ban is rarely necessary, and a once-a-month clarifying SLS wash is a useful reset for many readers, particularly in hard-water areas.
What's a good leave-in ingredient list to look for? A well-built curly leave-in has Aqua (water) as the first ingredient; a humectant such as Glycerin or Mel (honey) in the top five; a cationic surfactant such as Cetrimonium Chloride or Behentrimonium Methosulfate in the top eight (this is the conditioning workhorse and is the difference between a leave-in that softens and a leave-in that just smells nice); an emollient such as Butyrospermum Parkii (Shea Butter), Argania Spinosa Kernel Oil, or a Cetearyl Olivate ester for slip and softness; and a hydrolysed protein appropriate to your porosity if the formula is meant to strengthen as well as soften. A balanced preservative system at the bottom, and a single fragrance line, finish the list. See our leave-in conditioner guide for full picks.
What ingredients should I look for if I have high porosity hair? High-porosity hair has a raised cuticle that absorbs water and product quickly and loses both equally fast. The ingredient shortlist that works for it: Panthenol (Provitamin B5) as a humectant-plus-film-former that fills in cuticle gaps; hydrolysed proteins (Hydrolyzed Wheat, Hydrolyzed Keratin, Hydrolyzed Silk) to patch porosity from the inside; Ceramides (Ceramide NP, Ceramide AP, Ceramide EOP) to rebuild the lipid layer between cuticle scales; heavier sealing oils (Simmondsia Chinensis Jojoba, Argania Spinosa Argan, Ricinus Communis Castor) to slow moisture loss; and — used carefully and removed weekly — a non-soluble silicone such as Amodimethicone for the strands that need a literal physical seal to stop breakage. The full porosity-x-ingredient mapping sits in our how to choose curly hair products guide.
A note on where this list comes from
When Zenvy first started writing about ingredients, I made the mistake every founder makes — I reached for "natural good, synthetic bad" as the organising principle, because that is the story most curly-hair marketing tells. The first round of products we curated leaned heavy on it. Six months in, we noticed the same complaint from our high-porosity 4A and 4B community: their hair was breaking more on the all-natural formulas because they had no real film-former and no real sealing layer. That was the founder lesson. Function-first beats source-first. A well-formulated synthetic ester does the job a poorly-formulated coconut-oil cream can't. We now sort the Zenvy product collection by function category rather than by "clean," and the customer return rate halved within a quarter. The chemistry is the chemistry. Reading the label is the only durable defence.
If you do not yet know your curl type or porosity, the Zenvy AI Curl Identifier will tell you both from a single photo — that is the variable you need before this glossary becomes a routine.
Ingredients Glossary FAQ
What ingredients should I avoid in curly hair products?
Four high-risk categories: short-chain drying alcohols (Alcohol Denat., SD Alcohol 40, Ethanol, Isopropyl Alcohol) which strip moisture on already-dry curls; non-water-soluble silicones (Dimethicone, Amodimethicone, Phenyl Trimethicone, Trimethylsilylamodimethicone) which build up on low-porosity hair within two or three wash cycles; harsh anionic sulfates (Sodium Lauryl Sulfate, Ammonium Lauryl Sulfate) on dry, porous, or chemically-treated hair; and fragrance (Parfum) on sensitised scalps. None are universally bad — each becomes a problem on a specific hair state.
Are sulfates always bad?
No. Sodium Lauryl Sulfate and Sodium Laureth Sulfate are strong anionic cleansers — very effective at removing oil and residue, and the same efficiency makes them stripping for hair that is already dry, porous, or coloured. Gentler alternatives such as Cocamidopropyl Betaine and Decyl Glucoside cleanse roughly 30–60% less aggressively and are the right default for most curly routines. A full sulfate ban is rarely necessary; a monthly clarifying wash is a useful reset, especially in hard-water areas.
What's a good leave-in ingredient list to look for?
Water first; a humectant such as Glycerin or honey (Mel) in the top five; a cationic surfactant such as Cetrimonium Chloride or Behentrimonium Methosulfate in the top eight; an emollient such as Shea Butter, an oil, or an ester for slip and softness; and a hydrolysed protein appropriate to your porosity if strengthening is the goal. A balanced preservative system at the bottom finishes the formula.
What ingredients should I look for if I have high porosity hair?
Panthenol as a humectant-plus-film-former; hydrolysed proteins (Hydrolyzed Wheat, Hydrolyzed Keratin, Hydrolyzed Silk) to patch porosity from the inside; Ceramides to rebuild the inter-cuticle lipid layer; sealing oils (Jojoba, Argan, Castor) to slow moisture loss; and — used cautiously — a non-soluble silicone such as Amodimethicone where physical sealing is needed to stop breakage.
Does INCI order really matter on a label?
Yes — for the first 1% of the formula. Ingredients are listed in descending order of concentration down to 1%, after which they can be re-shuffled. So the order of the first five ingredients tells you what a product actually is, while the order of ingredients below the preservatives is a marketing decision. Honey listed after Phenoxyethanol is at fractional-percent inclusion. Honey listed in the top five is meaningful.
Why is fragrance (Parfum) on the watchlist if it's listed in tiny amounts?
Because a single "Parfum" or "Fragrance" line on an INCI list can legally represent a proprietary mix of over 200 individual aromatic compounds — the EU CosIng database treats the term as a permitted umbrella category. The total concentration is usually under 1%, but the number of distinct molecules makes fragrance the leading contact allergen in cosmetic products. Sensitised scalps benefit from fragrance-free or essential-oil-only formulas; most readers tolerate Parfum without issue.
