Gentle Cleansing Formula: Preservatives and Foam

Regarding your gentle facial cleansing formula with Lauryl Glucoside, Propylene Glycol, and Glycerin, and your question about preservatives and shelf life:

It is highly recommended to include a preservative in your formula. As the staff mentioned, without a preservative, it is impossible to guarantee the shelf life or safety of the product. Microbial contamination (bacteria, mold, yeast) can occur from various factors like ingredients, mixing environment cleanliness, and storage conditions (even in the refrigerator). A preservative system is necessary to protect the product from microbial growth and ensure it remains safe and stable for use over time.

Storing the formula in the refrigerator without a preservative will extend its life compared to room temperature, but it does not eliminate the risk of microbial growth. The shelf life would still be very limited and unpredictable, potentially ranging from a few days to a couple of weeks, depending heavily on the cleanliness of preparation and storage.

You also noted that Lauryl Glucoside provides little foam. This is a known characteristic of this gentle surfactant. To increase the lather and make the product more pleasant to use, you can follow the staff's suggestion and add a co-surfactant like Coco-Betaine or BabyFoam to your formula. These ingredients can help boost foam without significantly compromising the gentleness of the cleanser.

Remember to adjust the pH of the final formula using Citric Acid or Lactic Acid to a skin-friendly range (typically pH 5.0-6.5) after adding all ingredients, including the preservative and any foam boosters.