Optimizing Gentle Shower Gel Formula: Surfactants, Stability of Hydroalcoholic Extracts, and Commercial Viability

Thank you for sharing your experimental shower gel formula. It is a good starting point, and your current surfactant system is already quite mild. Here is a detailed analysis and recommendations for improving your formula for commercial viability and maximum skin gentleness.

1. Recommendations for a Commercial and Gentle Formula

To make your formula more marketable and gentle, focus on the following areas:

A. Surfactant Selection and Ratio (Answering Q3)

Your combination of AD25 (Cocamidopropyl Betaine) and N70 (Sodium Lauryl Ether Sulfate, SLES) is a classic and effective system.

• Gentleness: Your current ratio (14g AD25 to 4g N70) is excellent for gentleness, as the amphoteric surfactant (AD25) is used at a much higher concentration than the anionic surfactant (N70), which helps mitigate the potential irritation of SLES.
• Recommendation for Ultra-Gentleness: While your current formula is mild, for a premium, "ultra-gentle" product, you should consider replacing N70 (SLES) with an even milder anionic or non-ionic co-surfactant.
  • Option 1 (Mild Anionic): Replace N70 with an amino acid-based surfactant like AminoWash™ (Sodium Lauroyl Glutamate) (ID: 513) or Sodium Lauroyl Lactylate (ID: 125484).
  • Option 2 (Non-ionic): Replace N70 with a non-ionic surfactant like Lauryl Glucoside (ID: 177) or Coco Glucoside (ID: 178). These are very mild and derived from natural sources, which is good for marketing.

B. pH Adjustment

• Crucial Step: The pH of a body wash must be adjusted to match the skin's natural pH, typically pH 5.0 to 6.0. Your current blend of surfactants will likely result in a pH that is too high (often 6.5-7.5).
• Adjustment: Always check the final pH and adjust it down using a Citric Acid Solution (10-20%) until it is in the target range. This is essential for skin health and product stability.

C. Humectants and Conditioning Agents

• Glycerin: Your 4% Glycerin (ID: 143) is a good start. You can increase this to 5-7% for enhanced moisturizing properties without making the gel too sticky.
• Conditioning Polymer: To counteract the drying effect of surfactants and leave a soft, conditioned feel on the skin, add a conditioning polymer.
  • Recommendation: Add Poly-Conditioner 47 (Polyquaternium-47) (ID: 8597) at a concentration of 0.5-1.0%. This is highly effective in wash-off products for improving skin feel.
• Vitamin E: Vitamin E (Tocopherol) is oil-soluble and generally not effective in a wash-off product like a clear gel unless a dedicated solubilizer is used. Focus on water-soluble conditioning agents instead.

D. Preservative

• Your use of Phenoxyethanol (ID: 155) at 2% is higher than the typical maximum recommended usage rate of 1.0% in most regions. For a commercial product, reduce the concentration to 1.0% to comply with regulations and ensure safety.

2. Effect of Hydroalcoholic Extracts (12% Total)

The use of 12% hydroalcoholic extracts is the biggest risk factor for stability and clarity.

• Clarity and Color: At 12%, the natural pigments and compounds from Yanang, Lemongrass, and Pandan will almost certainly make the gel cloudy and colored (likely green/yellow/brown). Achieving a crystal-clear gel is highly unlikely.
• Stability and Separation: High concentrations of alcohol (which is present in hydroalcoholic extracts) can destabilize the surfactant system, leading to:
  • Cloudiness/Turbidity
  • Separation (especially after temperature cycling tests)
  • Viscosity Loss
• Recommendation: For better stability and clarity, reduce the total extract concentration to 2-5%. If you wish to keep the high concentration for marketing purposes, you must perform rigorous stability testing (heating/cooling cycles) and accept that the product will be colored and potentially cloudy.

4. Step-by-Step Mixing Procedure

For a liquid gel, the mixing process is straightforward:

1. Water Phase: Combine the DI Water, Glycerin (ID: 143), and any water-soluble conditioning agents (e.g., Poly-Conditioner 47 (ID: 8597)). Mix until homogeneous.
2. Surfactant Addition: Slowly add the primary surfactant, N70 (ID: 253119) or its replacement, to the water phase while stirring gently to minimize foaming.
3. Amphoteric Surfactant: Add the secondary surfactant, AD25 (Cocamidopropyl Betaine) (ID: 160), and mix until the solution is uniform.
4. Additives: Add the Hydroalcoholic Extracts and the Preservative (Phenoxyethanol) (ID: 155). Mix well.
5. Thickening: Slowly add the 10% Salt Solution while stirring. Stop adding salt once the desired viscosity is achieved. Note: You may need more salt than your current 2g to achieve a thick gel.
6. pH Adjustment (Crucial): Check the pH of the final mixture. If it is above 6.0, slowly add a Citric Acid Solution (10-20%) drop by drop until the pH is between 5.0 and 6.0.
7. Finalization: Allow the gel to sit for 24 hours to let any trapped air bubbles escape before packaging.

Proposed Gentle Formula Example (100g)