Recipe Note
Once the mixture is uniform, it’s time to test and adjust the pH.
To test and adjust the pH: create a 10% dilution by weighing 2g product and 18g distilled water into a small bowl or beaker and whisk to combine. Check the pH with your pH meter. We are aiming for a pH of 3.5–3.9; you will almost certainly need to raise the pH using more 10% NaOH solution, testing as you go. When the pH of the solution is ideal range, package it up!
Before you select a bottle, check the side of the beaker to see how much product you have left after pH testing and adjusting; you can end up losing a lot to testing as you get a feel for how much different amounts of the NaOH solution raise the pH.
If you are new to including AHAs in your skincare routine, please introduce this product to your routine slowly. We’d start with using a few drops of this serum ~3x a week, gradually working up to daily use. Avoid the eye area! I generally use this serum along with other watery serum type products, before any creams or oil serums. Pay attention to your skin, looking for signs of irritation, and discontinue/reduce use if your skin isn’t happy. Don't forget your daily sunscreen!
It is recommended that prior to exposure to the sun, users cover areas where serum has been applied, Contact of the product with the skin must be of limited frequency or duration.
SHELF LIFE & STORAGE
Because this serum contains water, you must include a broad-spectrum preservative to ward off microbial growth. This is non-optional. Even with a preservative, this project may eventually spoil as our kitchens are not sterile laboratories, so in the event you notice any change in colour, scent, or texture, chuck it out and make a fresh batch.
