Gentle Liquid Skincare Formula: Irritation, Preservation, and Storage

Hello, thank you for the formula you would like me to review.

Based on the formula you provided and the information from the expert, I can summarize the answers to your questions as follows:

Will this formula irritate sensitive skin?
This formula is considered quite gentle, as most of the ingredients do not have highly irritating properties. Specifically, Willow Bark Extract, which contains Natural Salicylic Acid, can be irritating at high levels, but at a concentration of 3%, it is considered quite low. However, gentleness does not mean that allergic reactions will not occur, as allergies are individual reactions to certain ingredients.

How long can this formula be stored without preservatives? Are preservatives necessary? Which one and at what percentage?
According to the information, there is no need to add additional preservatives to this formula. This is because some key ingredients, such as Lavender Water, Witch Hazel, and Galactomyces Ferment Filtrate (Pitera), which together make up 70% of the formula, already contain preservatives from the manufacturer. If the mixing process and storage are clean and hygienic, the resulting product can be stored for several years, or until the individual ingredients expire.

Can it be stored without refrigeration after mixing?
Yes, it can be stored outside the refrigerator. However, you should avoid storing it in areas with high temperatures, just like general cosmetic products.