What Does SLES-70 (1/2/3 EO) Mean? A Complete Guide
1. What is SLES?
SLES stands for Sodium Lauryl Ether Sulfate, an anionic surfactant commonly used in shampoos, body washes, and other personal care products. It is synthesized by ethoxylating lauryl alcohol (C12–C14 fatty alcohol) with ethylene oxide (EO) and then sulfonating the resulting compound. Its general chemical formula is:
RO(CH₂CH₂O)ₙSO₃Na,
where R is the alkyl chain (C12–C14), and n denotes the average number of ethylene oxide (EO) units.
2. What Does “70” Mean in SLES-70?
The number “70” refers to the active matter concentration, meaning the product contains approximately 70% active surfactant, while the remaining 30% consists of water and minor by-products (e.g., sodium sulfate, unsulfated alcohols).
- SLES-70: A paste-like form with 68–72% active content.
- SLES-28: A liquid form with 26–30% active content.
Higher concentrations like 70% are more cost-effective for shipping and storage but usually require dilution before formulation.
3. What Does 1EO / 2EO / 3EO Represent?
The EO number indicates how many ethylene oxide units are attached to each lauryl alcohol molecule on average. This directly affects the surfactant’s water solubility, foaming behavior, and skin mildness:
- 1EO: Low ethoxylation — stronger degreasing but higher irritation potential. Less common in personal care due to harshness.
- 2EO: Balanced — optimal mix of cleansing, mildness, and foaming. Most widely used type in personal care formulations.
- 3EO: Highly ethoxylated — greater hydrophilicity and better hard water tolerance. Preferred in areas with mineral-rich water or for industrial-grade cleaning.
4. Summary of Key Parameters and Their Effects
| Parameter | Chemical Meaning | Effect on Performance |
|---|---|---|
| SLES | Anionic surfactant | Core function: cleansing, emulsifying, foaming |
| 70 | 70% active matter | High concentration; affects formulation cost and viscosity |
| EO count | EO addition per molecule | 1EO: strong cleaner; 2EO: balanced; 3EO: better solubility & hard water resistance |
5. Application Recommendations
- Shampoos & Body Washes: Use 2EO SLES for balanced cleansing and skin-friendliness.
- Hard Water Areas or Industrial Cleaners: Choose 3EO SLES for improved resistance to calcium and magnesium ions.
- Heavy-Duty or Budget Cleaning Products: 1EO SLES offers strong degreasing at a lower cost but requires co-formulants to reduce irritation.
🔎 Note: The EO number affects the HLB (Hydrophilic-Lipophilic Balance), a critical variable in formulation stability and performance. 2EO SLES is typically stable in pH ranges from 7 to 9.5, making it compatible with most personal care systems.
