What it is
In the register’s words: “Propanediol is the organic compound.”
- EU register name (INCI)
- PROPANEDIOL
- CAS number
- 504-63-2
- EC number
- 207-997-3
What the register lists it for
These are the uses the European Commission’s CosIng register lists for Propanediol in any cosmetic, hair roles first. They say why a maker might add it, not what it does in one formula, and they aren’t a safety rating.
- Solvent
-
Dissolves other ingredients. Water is the most common; some alcohols and glycols carry this role too.
Register definition: “Dissolving other components of cosmetics. Solvents are usually liquids (aqueous and nonaqueous).”
- Viscosity controlling
-
Makes a product thicker or thinner, so a gel holds its shape or a shampoo pours. Gums, cellulose and some salts carry this role.
Register definition: “Increasing or decreasing the viscosity (thickness) of cosmetics.”
Where it sits on each label
US labels list ingredients from most to least, except that those at 1% or less may follow in any order. A name near the top is a large part of the formula. A label doesn’t mark where the 1% point falls, so further down, the order says little about how much is in it.
- Shampoos 7 labels First five names: 3 of 7 Shampoos without it
- Clarifying shampoos 3 labels First five names: 1 of 3 Clarifying shampoos without it
- Rinse-out conditioners 4 labels First five names: 3 of 4 Rinse-out conditioners without it
- Deep conditioners 6 labels First five names: 4 of 6 Deep conditioners without it
- Leave-in conditioners 2 labels First five names: 1 of 2 Leave-in conditioners without it
- Stylers 1 label First five names: 1 of 1 Stylers without it
- Heat protectants 1 label First five names: 1 of 1 Heat protectants without it
- Hair oils 1 label First five names: 0 of 1 Hair oils without it
- Curl refreshers 2 labels First five names: 1 of 2 Curl refreshers without it
Every label, product by product (27)
- PATTERN Hydration Shampoo Shampoo 4th of 42 names
- Kristin Ess Moisture Rich Curl Shampoo Shampoo 4th of 41 names
- Not Your Mother's Curl Talk Clean Slate Daily Shampoo Shampoo 4th of 22 names
- OLAPLEX Nº.4CURL Bond Shaper Hydrating Curl Shampoo Shampoo 30th of 62 names
- Curlsmith Essential Moisture Shampoo Shampoo 15th of 28 names
- Curlsmith Fragrance-Free Shampoo Shampoo 15th of 23 names
- OLAPLEX No.4 Bond Maintenance Strengthening Shampoo Shampoo 53rd of 78 names
- Ouidad Water Works Clarifying Shampoo Clarifying shampoo 3rd of 33 names
- Bounce Curl Gentle Clarifying Shampoo Clarifying shampoo 6th of 31 names
- Curlsmith Curl Reset Detox Shampoo Clarifying shampoo 16th of 27 names
- Cécred Hydrating Conditioner Rinse-out conditioner 3rd of 50 names
- tgin Triple Moisture Replenishing Conditioner Rinse-out conditioner 3rd of 33 names
- Not Your Mother's Curl Talk Clean Slate Daily Conditioner Rinse-out conditioner 4th of 30 names
- Bounce Curl Super Smooth Cream Conditioner Rinse-out conditioner · listed as **Propanediol 7th of 34 names
- Cécred Moisturizing Deep Conditioner Deep conditioner 3rd of 41 names
- Briogeo Don’t Despair, Repair! Deep Conditioning Mask Deep conditioner · listed as Propanediol* 4th of 40 names
- Not Your Mother's Curl Talk Deep Hydration Mask Deep conditioner 3rd of 30 names
- Curlsmith Double Cream Deep Quencher Deep conditioner 4th of 36 names
- Cantu Ultra Moisture Nourishing Mask Deep conditioner 6th of 26 names
- SheaMoisture Jamaican Black Castor Oil Strengthen & Restore Treatment Masque Deep conditioner 32nd of 35 names
- tgin Green Tea Super Moist Leave-In Conditioner Leave-in conditioner 5th of 34 names
- SheaMoisture Coconut & Hibiscus Hold & Shine Moisture Mist Leave-in conditioner 19th of 25 names
- Not Your Mother's Curl Talk Fragrance & Protein Free Sculpting Gel Styler 4th of 12 names
- OLAPLEX Nº.9 Bond Protector Nourishing Hair Serum Heat protectant 2nd of 31 names
- OLAPLEX Nº.7 Bonding Oil Hair oil 7th of 21 names
- Curlsmith Shake & Shine Curl refresher 3rd of 51 names
- PATTERN Hydrating Mist Curl refresher 30th of 52 names
Each line runs from the first name on a label to the last; a dot is where this ingredient sits. Makers change formulas now and then; if the list on your bottle differs, go by your bottle.
Your next step
Other solvent ingredients on these labels
- Water (Aqua/Eau) 166 labels
- Limonene 75 labels
- Isopropyl Alcohol 15 labels
- Pentylene Glycol 12 labels
- 1,2-Hexanediol 3 labels
- C13-14 Isoalkane 2 labels
Updated · The name, numbers and uses come from the European Commission’s CosIng entry (CC BY 4.0); we write the uses in US spelling and put the hair ones first. The labels are each maker’s own. The order rule is the FDA’s Cosmetics Labeling Guide. All our sources are on the Sources page.