SLES 70% vs SLS: Choosing the Right Surfactant

SLES 70% vs. SLS: Which Surfactant Should You Choose for Your Cleaning Products?

In the high-stakes world of industrial chemical formulation, choosing the right primary surfactant is the foundation of a successful cleaning product. If you check the ingredient list of shampoos, dishwashing liquids, or industrial degreasers, you will almost certainly encounter one of two names: Natriumlaurylsulfaat (SLS) or Sodium Lauryl Ether Sulfate (SLES).

Although their names appear nearly identical, the presence of the word “Ether” in SLES represents a major difference in performance, safety, and formulation flexibility. At Watercare Chemical, we help manufacturers select surfactants that optimize both cost efficiency and product quality.

The Chemistry: From SLS to SLES

To understand why SLES was developed, we must first examine SLS (Sodium Lauryl Sulfate). SLS is a powerful anionic surfactant produced by the sulfation of lauryl alcohol. Its ethoxylated form, known as Sodium Laureth Sulfate (SLES), is widely used in liquid detergents and personal care products due to its improved mildness and solubility.

However, SLS has a small, linear molecular structure, allowing it to interact aggressively with biological membranes. This explains both its strong cleaning power and its higher irritation potential.

The Ethoxylation Process

SLES 70% is produced through an additional step known as ethoxylation. During this process, ethylene oxide is added to lauryl alcohol before sulfation, introducing an ether linkage into the molecule.

This structural modification increases molecular size and alters the hydrophilic–lipophilic balance (HLB), making SLES more water-soluble, milder, and easier to formulate while maintaining strong cleaning performance.

Skin Irritancy: The Mildness Factor

One of the most common questions from formulators is: “Is SLES safer than SLS?” The answer is yes, especially in terms of skin and eye irritation.

• SLS Irritancy: SLS can penetrate the outer skin layer, disrupting the natural moisture barrier and causing dryness or irritation.
• SLES 70% Mildness: The ethoxylated structure makes SLES bulkier, reducing penetration and making it suitable for baby products, facial cleansers, and premium shampoos.

Viscosity Building and the “Salt Curve”

For liquid detergents, viscosity strongly influences consumer perception. Watery products are often seen as low quality, while thicker formulations are associated with better performance.

The Synergistic Effect of Salt

In aqueous systems, surfactants form micelles. When a small amount of sodium chloride is added to an SLES 70% formulation, micelles transform into elongated structures that entangle and increase viscosity.

SLES responds much better to salt thickening than SLS. When combined with CDEA (Cocamide DEA), the thickening and foam stability improve significantly, enabling rich, gel-like formulations without expensive thickeners.

Solubility and Hard Water Performance

Hard water containing calcium and magnesium ions can negatively affect surfactant performance.

• SLS in Hard Water: Forms insoluble residues, reducing foam and cleaning efficiency.
• SLES in Hard Water: Ether groups improve solubility and maintain stable foaming even in high-hardness conditions.

SLES 70% vs. SLS: Technical Comparison

Feature	SLS	SLES 70%
Uiterlijk	Powder or liquid	High-viscosity paste
Typical Concentration	30% or 90%+	70% standard
Mildness	Low	High
Foam Type	Large, flashy bubbles	Stable, creamy foam
Thickening	Requires special thickeners	Easily thickened with salt or CDEA
Applications	Industrial cleaners	Shampoos, dish soap, laundry liquid

The Economics of SLES 70% in Bulk Sourcing

SLES 70% offers major logistical and cost advantages in global trade.

• Shipping Efficiency: Higher concentration reduces freight cost per active kilogram.
• Storage Optimization: Requires less warehouse space than diluted versions.
• Improved Stability: High concentration naturally resists microbial growth.

Formulation Strategy: The “Golden Trio”

For cost-effective, high-performance liquid detergents, we recommend this synergistic system:

• SLES 70%: Primary surfactant for foam and mildness
• LABSA 96%: Secondary surfactant for grease-cutting and cost reduction
• CDEA: Foam booster and viscosity controller

Regulatory Considerations: 1,4-Dioxane

1,4-Dioxane is a potential byproduct of the ethoxylation process. Many countries impose strict limits on its presence in finished products.

Our SLES 70% undergoes vacuum stripping and strict quality control to ensure compliance with international safety standards.

Conclusion: Which Surfactant Should You Choose?

While SLS remains useful for heavy-duty and powder applications, SLES 70% is the preferred choice for liquid detergents and personal care products due to its mildness, easy thickening, and hard-water tolerance.

Last Updated on 2026-02-10 by system