pH Level for Toner with Lactic Acid

Regarding the pH level for your toner containing Lactic Acid used daily, a pH between 3 and 4 is effective for Lactic Acid to perform its exfoliating function. The staff confirmation and product information indicate that for exfoliation efficacy, the pH should be below 4.0, ideally around 3.5 (while the most effective is pH 2.5, for consumer products, the Thai FDA guideline is pH >= 3.5).

Your measured pH of around 3-4 is effective for exfoliation. However, using a toner with a pH as low as 3 daily, especially morning and evening, might cause skin irritation, redness, or sensitivity for some individuals. While effective, a pH slightly higher, closer to 3.5-4.0, might be gentler for frequent daily use while still providing exfoliation benefits.

How to Adjust pH:
If you experience irritation, you can try to increase the pH slightly using a pH adjuster like Triethanolamine or Sodium Hydroxide solution, adding a very small amount at a time and re-measuring until you reach a pH between 3.5 and 4.0.

Ingredient for Faster Drying Without Dryness

To help your toner dry faster without causing skin dryness, you can add MOIST24 (Glycereth-26) at a concentration of around 5%. MOIST24 is a humectant that helps retain moisture in the skin and can improve the texture and absorption speed of the formula, making it feel less sticky and dry down faster while keeping the skin hydrated.