First, thanks for checking this topic out. I formulated this Vitamin C serum (with ingredients as below) and it got recrystalized after 4 days. How can I fix this issue?
Deionized Water: 25%
Ascorbic Acid: 20%
Licorice Extract: 1%
The serum was totally clear after I kept stirring the mixture in hot water (i mean double-boiled) for 10-15 minutes. But it got recrystalized after 4 days. Is it due to the 1,3-Propanediol?