Formula Analysis and Recommendations

You're aiming for a facial cleanser that leaves the skin feeling clean, not slippery or coated, but also not overly dry or "squeaky." This is a common goal, and it depends heavily on the type and concentration of surfactants and humectants used.

Your First Formula

• Glycerin 35%
• Xanthan Gum 0.5%
• Lauryl Glucoside 5%
• AminoWash 20%
• Coco Betaine 10%
• Water (approx. 29.5%)
• Lactic Acid (for pH adjustment)
• Phenoxyethanol (amount unknown)

In this formula, the high concentration of Glycerin (35%) is likely the primary contributor to the slippery or "filmy" feel you want to avoid after rinsing. Glycerin is an excellent humectant, but at such a high percentage, it can leave a noticeable residue on the skin surface. The total surfactant concentration (Lauryl Glucoside 5% + AminoWash 20% + Coco Betaine 10% = 35%) is also quite high for a facial cleanser, although the chosen surfactants (AminoWash and Coco Betaine) are considered gentle. At this concentration, it could potentially lead to a "squeaky clean" feel or dryness, although the high Glycerin might counteract the dryness but contribute to the slippery feel.

Your Second Formula

• Glycerin 20%
• AminoWash 20%
• Coco Betaine 20%
• Xanthan Gum 0.5%
• Phenoxyethanol (amount unknown)
• Water (approx. 39.5%)

This formula reduces the Glycerin content to 20%, which should feel less slippery than 35%. However, the total surfactant concentration is increased to 40% (AminoWash 20% + Coco Betaine 20%). While this higher surfactant level might give a stronger "clean" feel, it could also potentially be more stripping or still feel slightly slippery depending on the specific grades of surfactants used and their interaction at this high concentration. Compared to the first formula, the lower Glycerin will likely make it feel less slippery, but the higher total surfactant load might make it feel more stripping.

Staff's Suggested Base Formula

• Glycerin 10%
• AminoWash 20%
• Coco Betaine 20% (Note: Staff reply suggests reducing AminoWash if too slippery)
• Phenoxyethanol 1%
• Water (approx. 49%)
• SugarThick (optional thickener)

This formula significantly reduces the Glycerin to 10%, which is much less likely to leave a slippery or filmy residue compared to 35% or 20%. The surfactant concentration remains high at 40% (20% AminoWash + 20% Coco Betaine), and the staff notes that this might still feel "quite slippery" and suggests reducing the AminoWash. Reducing AminoWash to 10-15% would lower the total surfactant load and likely result in a less slippery feel while still providing effective cleansing.

Answers to Your Questions

1. Is the amount of surfactants too high in the first formula?
   The total surfactant concentration in your first formula (35%) is quite high for a facial cleanser, especially if you want to avoid a slippery feel. While the individual surfactants are gentle, the high overall percentage can contribute to the post-rinse feel. The second formula and the staff's base formula have an even higher total surfactant load (40%). To achieve a less slippery feel, you might consider reducing the total surfactant concentration, particularly the AminoWash, as suggested by the staff.

2. How much preservative (Phenoxyethanol) should be added?
   Phenoxyethanol is typically used at a concentration of 0.5% to 1.0% in cosmetic formulas. For general facial cleansing products, a usage rate of 1% Phenoxyethanol is common and effective for preservation. For products used around the eyes, a lower concentration of 0.5% is often recommended.

3. Are the mixing steps correct/appropriate?
   Your initial mixing steps are functional, especially pre-dispersing Xanthan Gum with Glycerin to prevent clumping. However, a more standard approach, as suggested by the staff, is to create the water phase first (including Glycerin), then add the thickener (like Xanthan Gum or SugarThick) and mix until the desired gel consistency is achieved. After the base is formed, you would add the surfactants, mix thoroughly, adjust the pH using Lactic Acid, and finally add the preservative (Phenoxyethanol). Using SugarThick as suggested by the staff can make viscosity adjustment easier after the main ingredients are combined.

Recommendation for Achieving Desired Feel

To achieve a clean feel without slipperiness or film, while avoiding a squeaky feel, consider starting with a modified version of the staff's suggested base formula:

• Reduce Glycerin to 10% or even lower (e.g., 5-10%) to minimize the slippery feel.
• Consider reducing the total surfactant concentration. The staff suggested reducing AminoWash from 20% down to 10-15%. A starting point could be:
  • AminoWash 10-15%
  • Coco Betaine 10-15%
  • Lauryl Glucoside 5% (optional, can be removed or reduced if you want less foam or a less slippery feel)
• Use a thickener like Xanthan Gum (0.5%) or SugarThick (1-3%) to get the desired gel texture. SugarThick is easier to adjust later.
• Add 1% Phenoxyethanol as the preservative.
• Adjust the pH to the skin-friendly range (typically 5.0-6.5) using Lactic Acid after all other ingredients are mixed, just before adding the preservative.
• The remainder of the formula should be Water.

Example Adjusted Formula (starting point):

• Glycerin 10%
• AminoWash 15%
• Coco Betaine 10%
• Xanthan Gum 0.5% (or SugarThick 1-3%)
• Phenoxyethanol 1%
• Lactic Acid (as needed for pH adjustment)
• Water (qs to 100%)

Mix the water and Glycerin, then add the thickener (Xanthan Gum dispersed in a little Glycerin or water first, or SugarThick) and mix until uniform. Add the AminoWash and Coco Betaine and mix gently to avoid excessive foam. Adjust the pH with Lactic Acid. Finally, add the Phenoxyethanol and mix. Test the feel and adjust the percentages of Glycerin and surfactants in subsequent batches if needed to fine-tune the post-rinse feel.