Preservative Use in Herbal Glycerin Soap

Regarding the issues encountered with using Phenoxyethanol SA in your herbal glycerin soap:

• Temperature Sensitivity: Phenoxyethanol SA is sensitive to high temperatures. Heating it above 60°C can reduce its effectiveness. Reheating the soap mixture after adding the preservative likely compromised its ability to protect the product.
• pH Limitation: Phenoxyethanol SA is effective within a pH range of 2.0 to 6.0. Since your soap has a pH of 7, it is outside the effective range for this preservative. Glycerin soaps typically have a higher pH (often 8-10), making Phenoxyethanol SA generally unsuitable for this type of product. At pH 7, Phenoxyethanol SA will not provide adequate preservation.
• Herbal Ingredients: As mentioned previously, using fresh or powdered herbs can introduce a high microbial load into your soap. Proper sterilization of herbal ingredients before adding them to your formulation is crucial. Even with an effective preservative, a high initial level of microbes can overwhelm the preservative system and lead to spoilage, such as mold growth.

To address these issues and ensure proper preservation for your herbal glycerin soap, consider using a preservative that is effective at a higher pH range.

A suitable alternative is Mild Preserved™ COS, which is effective in a pH range of 2 to 8 and provides broad-spectrum protection against bacteria, mold, and yeast. It should be added when the product temperature is below 45°C.

The previous issue with mold when using regular Phenoxyethanol was likely because it is less effective against fungi compared to Phenoxyethanol SA or other broad-spectrum options. However, even broad-spectrum preservatives like Phenoxyethanol SA are not effective at the pH of typical glycerin soap.

Therefore, you should not rely on the Phenoxyethanol SA that was exposed to high heat and is being used at an unsuitable pH. It is recommended to use a preservative like Mild Preserved™ COS that is compatible with the pH of your soap and ensure proper handling and sterilization of your herbal ingredients.