The pH of Sodium Lauryl Ether Sulfate (SLES) powder, when measured as a 1% aqueous solution, typically ranges between 6.5 and 9.5.
Understanding SLES pH
Sodium Lauryl Ether Sulfate (SLES) is a widely used anionic surfactant, often found in various personal care and cleaning products. While typically supplied in concentrated liquid or paste forms, when referred to as 'powder,' its pH is almost always determined by dissolving a specific concentration (commonly 1%) in water to form an aqueous solution. This method provides a practical and standardized way to measure its acidity or alkalinity, which significantly impacts its performance and compatibility in formulations.
The pH value is crucial for SLES as it influences:
- Formulation Stability: The stability of the final product, preventing degradation or separation of ingredients.
- Skin Compatibility: Products used on skin (like shampoos and body washes) often aim for a pH close to the skin's natural pH (around 5.5) to minimize irritation. Formulators adjust the pH of SLES-containing products to achieve this.
- Cleaning Efficiency: The effectiveness of SLES as a cleansing agent can be influenced by the pH of the solution.
- Solubility and Viscosity: pH can affect how well SLES dissolves and the thickness of the final product.
Key Specifications of SLES
Beyond pH, several other technical specifications define the quality and performance of SLES. These parameters ensure the product meets industry standards for various applications.
| Item | Standard |
|---|---|
| Active Matter Content (%) | 70 ± 2 |
| Unsulfated Matter Content (%) | 3.5 max |
| Sodium Sulfate Content (%) | 1.5 max |
| pH Value (1% aqueous solution) | 6.5 – 9.5 |
These standards are vital for manufacturers to produce consistent and effective SLES batches. For example, a high active matter content indicates a more concentrated and efficient product, while low unsulfated and sodium sulfate content helps reduce potential irritation and improve product purity.
Practical Implications in Formulations
Formulators often adjust the pH of SLES-based products. For instance:
- Shampoos and Body Washes: The final pH is typically adjusted downwards (acidified) to a range of 5.0-6.5 using mild acids like citric acid, aligning with the skin's natural pH to ensure gentleness and improve hair cuticle smoothness.
- Laundry Detergents: These might operate at a higher, more alkaline pH to enhance cleaning power, especially for certain types of stains.
Understanding the initial pH of the SLES raw material is the first step in formulating a stable and effective end product. For more information on the properties and applications of surfactants like SLES, you can explore resources like Surfactant Science & Technology (placeholder for a general credible source).
