Hello. 1. If completely dissolved in the formula, according to theory, should be equally effective. What is different is the case of mixing in a formula that is dispersed. (The formula does not contain water. or any solvent that helps dissolve
Vitamin C can) by 2. It's difficult to answer, it's enough because there are no ingredients that help maintain efficiency.
ascorbic acid got 100% using multiple helpers It may increase the shelf-life of
ascorbic acid but you will need to test it. Compare with the expectation of the members that the level is enough 3. I don't know, sorry, as far as I know
ascorbic acid but very low soluble in glycol. 4.
ascorbic acid Niacinamide The problem cannot exist. in the same formula But other parts have no problem, the severity must depend mainly on the user if
ascorbic acid 15% I think it shouldn't be a problem. because the other 2 items are not used at a high rate. 5. Yes, but the problem is instability. As the members know. 6. Can do. Recommended 1-3%. 0.5% may be too weak.