Just a quick post to announce that I purchased an Apera SX620 pH meter (3pt calibration). I’ll probably on occasion still use Macherey-Nagel pH strips to test some products such as ones that aren’t for the face to avoid contamination.

I purchased a meter because my favorite Vitamin C serum from Cosmetic Skin Solutions was discontinued. I decided to try Paula’s Choice C15 serum (so far so good!) because of the price, but the pH strips made the serum look Continue reading →