Instructions

1. Add essential oil (if using) to the glycerin and stir gently to combine.
2. In a separate container, dissolve the L-ascorbic acid powder into the distilled water. Stir thoroughly until fully dissolved. This may take a minute or two.
3. Add the glycerin (with or without essential oil) into the dissolved Vitamin C mixture and stir well to combine.
4. Add the preservative if using. Mix thoroughly.
5. Test the pH using pH strips. It should fall between 3.0 and 3.5. If it’s too acidic (lower than 3.0), add a tiny bit morewater. If it’s too high (above 3.5), it won’t be as effective—add a very small pinch of Vitamin C powder.
6. Transfer your serum into a dark glass dropper bottle to protect it from light. Store in the fridge and use within a few weeks.