Preservative Usage Rate for Cosmetics (Phenoxyethanol)

The amount of preservative like Phenoxyethanol to use in a cosmetic product depends on the specific type of Phenoxyethanol and the overall formulation. Generally, Phenoxyethanol-based preservatives are used at a concentration range of 0.5% to 1.25%.

For a 500g batch of cosmetic product:

• At a 0.5% usage rate, you would use 0.005 * 500g = 2.5 grams.
• At a 1.0% usage rate, you would use 0.010 * 500g = 5.0 grams.
• At a 1.25% usage rate, you would use 0.0125 * 500g = 6.25 grams.

Therefore, for 500g of product, you would typically add between 2.5g and 6.25g of a Phenoxyethanol-based preservative, depending on the specific product's recommended usage rate and the requirements of your formula.

Common types include standard Phenoxyethanol (like Phenoxyethanol (Extra Pure) or Phenoxyethanol P5), which is primarily effective against bacteria but may need to be combined with other preservatives for broad-spectrum protection against fungi. Products like Phenoxyethanol SA (eq. Optiphen Plus) or Chlorphenesin / Phenoxyethanol (Microcare PHC eq.) are examples of broad-spectrum blends.

Regarding the shelf life or stability after mixing, it's important to distinguish between physical stability and microbial safety. Preservatives like Phenoxyethanol ensure microbial safety by preventing the growth of bacteria, yeast, and mold. However, the overall shelf life (how long the product remains stable in terms of texture, color, and efficacy) depends on the entire formula, the quality of ingredients, manufacturing cleanliness, packaging, and storage conditions.

To determine the exact effective shelf life and ensure microbial safety for your specific formula, a challenge test is always recommended before producing and selling the product.