Adjusting pH in Activated Resorcinol Formulations
Question
After mixing all ingredients, the formulation has a pH greater than 6. What type of pH adjuster should be used to bring the pH back down to 4-5?
This formulation contains Activated Resorcinol. Based on the product details, AHA group substances should not be used as they would affect the effectiveness of Activated Resorcinol.
Answer
Adjusting pH in Formulations with Activated Resorcinol
When adjusting the pH of a formulation containing Activated Resorcinol, it is important to avoid using AHAs (Alpha Hydroxy Acids) as they can negatively impact the stability and effectiveness of Activated Resorcinol. The optimal pH range for Activated Resorcinol is 4.5-5.5.
To lower the pH from above 6 to the desired range of 4-5 (or ideally 4.5-5.5), you can use Citric Acid.
How to use Citric Acid to adjust pH:
- Citric Acid is a common and effective pH adjuster for cosmetic formulations.
- It is easily soluble in water.
- Add a small amount of Citric Acid gradually to your formulation.
- Stir well until dissolved.
- Measure the pH after each small addition.
- Repeat until the desired pH (4-5, ideally 4.5-5.5) is reached.
Using Citric Acid allows you to adjust the pH to the optimal range for Activated Resorcinol without using AHAs, thus preserving its efficacy.
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