Resolving Separation and Solidification in Surfactant Formulations

The issues you are facing—separation and the formula setting almost solid—are primarily due to the high concentration of solid surfactants relative to the water and liquid surfactant content.

Analysis of the Issues

1. Solidifying: Sodium Cocoyl Isethionate (SCI) is a solid surfactant with limited water solubility. At 12%, it often recrystallizes or forms a thick paste, especially when combined with Cocamide MIPA, which is a very efficient thickener. This combination is likely what is causing your recipe to "set" like a solid.
2. Separation: Your Fragrance level is very high at 3%. Fragrance oils require a robust and stable surfactant system to remain solubilized. When the SCI starts to precipitate (solidify) or if there isn't enough liquid surfactant to emulsify the oil, the formula will separate.

Recommended Alterations

To keep the formula liquid and stable, you should shift the ratio toward the liquid surfactant and reduce the solid components. Since you can change the ratios of the starred ingredients (totaling 32% of your formula), I recommend the following adjustment:

• Decyl Glucoside: Increase to 24%. As a liquid non-ionic surfactant, increasing this will help solubilize the high fragrance load and keep the overall system fluid.
• Sodium Cocoyl Isethionate: Decrease to 7%. This reduction prevents the formula from turning into a solid paste while still providing the creamy, dense foam that SCI is known for.
• Cocamide MIPA: Decrease to 1%. At this level, it will still provide excellent foam stabilization and some thickening without causing the product to set into a solid block.

Summary of the Adjusted Ratios:

• 49% Water
• 24% Decyl Glucoside (*)
• 7% Sodium Cocoyl Isethionate (*)
• 10% Cocamidopropyl Betaine
• 1% Cocamide MIPA (*)
• 3% Sodium Lactate
• 3% Fragrance
• 2% Panthenol
• 1% Preservative

This adjustment maintains the same total percentage for the starred ingredients but balances the solid-to-liquid ratio for a stable, pourable product. If separation still occurs, you may need to reduce the fragrance to 1% or add a solubilizer.