Analysis of Your Hair Serum Formula

This formula is designed as a leave-on treatment for oily scalp and dandruff, utilizing key active ingredients like Zinc Pyrithione and Piroctone Olamine. Here's an analysis of your formula and mixing steps, addressing your questions:

Formula and Mixing Steps Review

• Ingredients: The selection of Zinc Pyrithione, Dandruff-Guard™ (Piroctone Olamine), and Zinc PCA is suitable for targeting dandruff and oily scalp concerns in a leave-on product. Phenoxyethanol is an appropriate preservative. Ethanol helps dissolve Piroctone Olamine.
• Mixing Steps:
  • Step 1: Dissolving Dandruff-Guard™ in ethanol before adding to the water phase is correct, as Piroctone Olamine is soluble in ethanol. Forming the gel with Pro Polymer™ in water first is also the standard method.
  • Step 2: Adding Zinc PCA after the gel is formed is appropriate, especially since Zinc PCA is an electrolyte that can affect the gel's viscosity.
  • Adding Zinc Pyrithione: Since Zinc Pyrithione is insoluble, it needs to be properly dispersed in the formula to prevent settling. Simply "mixing until combined" might not be sufficient for long-term stability. High-speed blending is recommended to ensure even dispersion throughout the gel base.
• Potential Adjustments:
  • pH: The formula does not include a pH adjustment step. Zinc PCA has optimal solubility between pH 4-6, and Zinc Pyrithione's efficacy can be influenced by pH. It is highly recommended to check the final pH of your serum and adjust it to be within the 4-6 range for optimal ingredient performance and stability.
  • Zinc PCA Concentration: While 1% Zinc PCA is effective for oil control, the product description suggests 0.2-0.3% for dandruff treatment in shampoos/tonics. Using 1% is acceptable for a serum targeting oily scalp, but be aware it contributes significantly to the electrolyte load affecting the gel.

Pro Polymer™ Percentage for Suspension

Zinc Pyrithione is an insoluble powder (or liquid dispersion that behaves similarly regarding suspension needs) and requires sufficient viscosity to remain suspended and prevent settling over time. Your formula also contains 1% Zinc PCA, which is an electrolyte. The description for Pro Polymer™ indicates that electrolytes can reduce the viscosity of the gel, requiring a higher concentration of Pro Polymer™ to achieve the desired thickness and stability.

To prevent 0.5% Zinc Pyrithione from precipitating in the presence of 1% Zinc PCA, you will likely need a higher percentage of Pro Polymer™ than for a standard gel. The product description suggests using 2-3% or more of Pro Polymer™ when significant electrolytes are present.

Therefore, you should start testing with at least 1.5-2% Pro Polymer™ and adjust upwards as needed to achieve a stable gel consistency that keeps the Zinc Pyrithione evenly dispersed without settling over time. The exact percentage will require testing with your specific ingredients and mixing equipment.

Suitability for a Tonic

No, this formula, as written with 0.5% Zinc Pyrithione, is not suitable for a low-viscosity tonic.

As noted earlier and in the product information, Zinc Pyrithione is insoluble. It requires a viscous base, like a serum or gel created by Pro Polymer™, to keep the particles suspended and prevent them from settling at the bottom of the container.

A tonic is a low-viscosity liquid. If you were to remove or significantly reduce the Pro Polymer™ to make a tonic, the Zinc Pyrithione particles would precipitate out of the solution, making the product ineffective and aesthetically unappealing.

To create an anti-dandruff tonic, you would typically need to use a soluble anti-dandruff active ingredient, such as Piroctone Olamine (which is included in your formula and is soluble in ethanol) or formulate with a much lower concentration of an insoluble active, or use a different suspension system designed for low-viscosity liquids, which can be challenging. Since your goal is to use 0.5% Zinc Pyrithione, a gel or serum format is necessary for stability.

In summary, your formula is a good starting point for a leave-on anti-dandruff serum. Pay close attention to the Pro Polymer™ concentration to ensure stable suspension of Zinc Pyrithione, consider adjusting the final pH, and ensure thorough dispersion of the Zinc Pyrithione during mixing.