Ingredient Compatibility, Reactions, and pH

Question

I have a few questions regarding ingredient compatibility and pH:

1. Why can't Zinc PCA and Potassium Azeloyl Diglycinate be used together?
2. Will Niacinamide react with Salicylic Acid? I suspect that Niacinamide, which has an amide bond, might undergo hydrolysis when in water with acid as a catalyst, potentially turning into niacin. Is this correct? I saw a formula on your website.
3. Does Calendula Officinalis Extract have a specific pH range that should not be exceeded or fallen below? It is not mentioned on the website.

MySkinRecipes Expert · Accepted Answer

Ingredient Compatibility and pH

Here is the information regarding the compatibility and pH levels of the ingredients you asked about:

Zinc PCA and Potassium Azeloyl Diglycinate: These two ingredients cannot be used together because they will cause precipitation.
Niacinamide and Salicylic Acid: A reaction can occur between Niacinamide and Salicylic Acid if the pH is too low. This can lead to the hydrolysis of Niacinamide into Niacin. To avoid this, it is recommended to adjust the pH of the formulation to be above 3, and ideally above 4.
Calendula Officinalis Extract: The suitable pH range for Calendula Officinalis Extract is 5-7.