Charge Compatibility and Transparency in Cleansing Formulation

Question

Hello!
I am formulating a cleaning product containing:

9% Coco Glucoside
6% Polyglyceryl-10 Laurate
3% Sodium Cocoyl Isethionate
0.01% Quaternium-73
1% GuarCat™ Clear
1% Chito-HD™ (Hair Conditioning From Chitosan, Natural Hair Conditioner)

Can this formula cause charge conflicts between the ingredients causing precipitation? I want the finished product to be durable and transparent!

Answer 1

In your formulation, there is a potential for charge conflict and solubility issues that could affect the transparency and stability of the final product. Here is a technical breakdown of the interactions:

1. Charge Compatibility (Anionic vs. Cationic)

Your formula contains a mixture of different charges:

Anionic: Sodium Cocoyl Isethionate (BabyFoam™).
Cationic: GuarCat™ Clear, Chito-HD™, and Quaternium-73.
Non-ionic: Coco Glucoside and Polyglyceryl-10 Laurate.

When anionic surfactants (negative charge) meet cationic polymers (positive charge), they can form a "coacervate" or a complex. While this is often desired in conditioning shampoos to help the polymers stick to the hair, an imbalance—especially with high levels of cationic materials like 1% GuarCat™ Clear and 1% Chito-HD™—can lead to precipitation (cloudiness or white flakes).

2. Solubility and pH Requirements

The pH of your system is the most critical factor for transparency:

Chito-HD™ (Chitosan): Requires a pH lower than 6.0 to remain soluble in water.
GuarCat™ Clear: Requires a pH lower than 7.0 to dissolve properly.
Coco Glucoside: This surfactant is highly alkaline (pH ~11.5).

If you mix these without immediate pH adjustment, the cationic polymers will likely precipitate or fail to dissolve, resulting in an opaque or unstable mixture. You must use an acid (like Citric Acid or Lactic Acid) to bring the pH down to the 5.0–5.5 range.

3. Transparency Challenges

Achieving a "water-clear" look with high levels of polymers is difficult:

Polymer Concentration: Using 1% of both GuarCat™ Clear and Chito-HD™ is quite high for a clear formula. Typically, these are used at 0.1%–0.2% to maintain high transparency. At 1%, the formula may become very viscous and slightly hazy.
Sodium Cocoyl Isethionate: This ingredient can sometimes settle or cause haziness in liquid formulas. It is highly recommended to add 0.1% Disodium EDTA to help stabilize it and maintain clarity.

Recommendations for Stability:

Order of Addition: Dissolve the cationic polymers (GuarCat™ Clear and Chito-HD™) in water first, then adjust the pH to below 6.0 before adding the surfactants.
Chelating Agent: Include 0.1% Disodium EDTA to prevent the Sodium Cocoyl Isethionate from hardening or settling.
Light Protection: Quaternium-73 is sensitive to light. To ensure the product is "durable" and doesn't change color, use opaque packaging or a UV-protected bottle.
Trial Reduction: If the formula is too cloudy, try reducing the GuarCat™ Clear and Chito-HD™ to 0.2% each.