High Purity Grade
High purity caustic soda is also referred to as membrane, mercury, rayon, or low-salt grade product. The product has the same NaOH concentration as standard grade but has lower levels of impurities such as salt and iron. This high purity product typically sells at a higher price than standard grade product and therefore is used in those applications that require the lower levels of these key components.
Standard grade product is also known as diaphragm grade. Approximately 70% of all U.S. chlor-alkali production uses diaphragm technology. Product of this quality is suitable for the vast majority of all caustic soda use applications.