Hello, please allow me to ask. Please help the admin answer.
Made 1 serum formula, using Niacinamide 5.5% + Ethyl Ascorbic acid 0.75%, etc.
But now, the formula has salt-like stains clinging to the mouth of the bottle. Some are white, some are creamy. For what reason?
So how can you fix it?
Please ask for advice.
thank you