Review of Hair Root Serum Formulation (200 ML)

Here is a review of your hair root serum formulation based on your questions:

1. Amount of Biotin (Biotinyl-GHK and Biotin Express)

Your formula uses 3% Biotinyl-GHK and 1% Biotin Express. Based on the product information:

• Biotinyl-GHK: The recommended usage rate is 1-3%, and you are using 3%, which is within the recommended range.
• Biotin Express: This is a 10% concentration of Biotin. Using 1% Biotin Express means you are adding 0.1% pure Biotin to the formula. The recommended usage rate for Pure-Biotin is 0.1-0.2%. Your usage of 0.1% pure Biotin from Biotin Express is within this recommended range.

Both ingredients are used within their individual recommended usage rates. While this combination provides a significant amount of biotin activity, the amounts are within the guidelines for each specific product.

2. Need for Preservative

You asked if a preservative is unnecessary because distilled rosemary water makes up more than half the formula. Distilled rosemary water, while a natural ingredient, does not provide sufficient antimicrobial protection on its own to preserve a water-based cosmetic product for typical shelf life and usage (repeated opening and closing).

Additionally, while the Natural Moisturizing Amino Acids ingredient contains Phenoxyethanol as a preservative, the amount contributed to the final formula (2% of the ingredient * 0.5% Phenoxyethanol in the ingredient = 0.01% Phenoxyethanol in the final formula) is far too low to effectively preserve the entire 200ml product.

Therefore, it is highly recommended to add a broad-spectrum preservative system suitable for water-based formulas to prevent microbial growth and ensure the safety and stability of your serum throughout its intended shelf life.

3. Amount of Scalp Moisturizer (Natural Moisturizing Amino Acids)

Natural Moisturizing Amino Acids is an excellent ingredient for providing moisture. The recommended usage rate for this ingredient in leave-on hair products (like a hair root serum) is 0.5-1%. Your formula uses 2%.

Using 2% is higher than the recommended rate for leave-on hair applications. While it will provide moisturizing benefits, using it at a higher concentration than recommended for leave-on products could potentially make the scalp feel sticky or overly oily. You may consider reducing the amount to within the 0.5-1% range to optimize the feel on the scalp while still providing effective moisturization.

I hope this review is helpful for your formulation!