Sodium lauryl sulfate and sodium laureth sulfate are the most commonly used surfactants when formulating hair shampoos due to their excellent foaming ability and the ease of viscosity adjustment. However, when formulating a body wash or body shampoo, a milder or less irritating surfactant is preferred. Sodium lauroyl or cocoyl isethionate (SCI) is frequently used as a replacement.
Innospec Active Chemicals, Edison, NJ, has a product called Iselux LQ-CLR-SB (INCI name: Sodium lauroyl methyl isethionate), which is made by adding a methyl group to SCI. Apparently, this minor modification makes a dramatic difference in properties.It exhibits excellent water solubility so it can be used in clear systems; it furnishes a dense, creamy long lasting lather and smooth after feel; it is very mild so it can be used on sensitive skin; it is free of sulfates, 1,4-dioxane and nitrosamines; it is readily biodegradable and derived from natural feedstocks; and is easily formulated with broad pH stability (from pH 4.5 – 8.5).
In addition to its use in bath or shower products, it is also recommended in beauty bars, hand or facial cleansers, shaving preparations and baby cleansing applications.
Iselux is also said to form structured liquid systems. If used in combination with certain co-surfactants, Iselux will promote the formation of a liquid crystalline structure that can suspend and deliver active ingredients or other components such as oils and conditioning agents. The lathering properties of Iselux are not affected by these ingredients.It is possible to create visual effects such as layering different colored phases to form stripes or suspending beads, glitter or other solid particles. Among the oils and conditioners that can be incorporated are silicones, petrolatum and emollient esters.
When formulating with Iselux flakes, a sufficient amount of chelating agent should be used to ensure a clear solution (0.3% active chelate for every 10% active Iselux).Using a co-surfactant, such as sodium alkyl- amphoacetate or disodium alkylamphodiacetate, will reduce or eliminate the need for chelating agents. Electrolytes such as sodium chloride can be added to increase the viscosity of the product.
The following formulation is given as an illustration of the use of Iselux.
Waterq.s. to 100%
Guar hydroxpropyltrimonium 0.2
Disodium cocoamphodipropionate 7.5
(Miranol C2M Conc)
Sodium methyl cocoyl taurate 7.5
Cyamopsis tetragonoloba guar gum 0.5
Cocamide MEA 3.5
Canola oil 10.0
C12-15 alkyl benzoate 2.0
Preservative, dye, perfume q.s.
50% Citric acid solution q.s. to pH 5.0-5.6
Procedure: Mix constantly. Dissolve the salt in the deionized water, and slowly blend the third ingredient until dispersed and uniform. Add Miranol and heat to 40-45°C. Add the cocoyl taurate.
In a separate vessel, add glycerin and the guar gum and blend into a uniform, soft slurry. Add this to main tank. Add Iselux and cocamide MEA. Remove heat source and add betaine. In a separate container, mix canola oil and C12-15 alkyl benzoate and add to main tank.Add desired preservative, dye or perfume. Adjust pH to 5.0-5.6 with the citric acid. Lowering the pH should thicken the system.
Mix for 30 minutes to reach final consistency.
Harvey Fishman has a consulting firm located at 34 Chicasaw Drive, Oakland, NJ 07436, firstname.lastname@example.org, specializing in cosmetic formulations and new product ideas, offering tested finished products. He has more than 30 years of experience and has been director of research at Bonat, Nestlé LeMur and Turner Hall. He welcomes descriptive literature from suppliers and bench chemists and others in the field.