Alternative pH Adjusters for BHA Formulas

Question

My BHA formula (e.g., Salicylic Acid or Willow Bark based) has a high pH and I need to lower it to the optimal range (3.3-3.5) for a leave-on product, but I don't have Citric Acid. What alternative acidic ingredients can I use to adjust the pH? How should I perform the pH adjustment carefully to avoid over-acidifying the formula?

MySkinRecipes Expert · Accepted Answer

Alternative pH Adjusters for BHA Formulas

If your BHA formula (Willow Bark + Water + Xanthan Gum or Salicylic Acid + Propylene Glycol + Water + Allantoin) is too alkaline and you need to lower the pH, there are several acidic ingredients you can use as alternatives to Citric Acid. The goal is typically to reach a pH between 3.3 and 3.5 for optimal BHA efficacy and reduced irritation in leave-on products.

Here are some suitable options available:

Lactic Acid (AHA): This is a common alpha hydroxy acid (AHA) that works well for lowering pH in cosmetic formulas. It also offers additional benefits like exfoliation and hydration. We have concentrated forms available such as Lactic Acid (AHA) 90% (ordinary grade - smells) and Lactic Acid (AHA) 90% Deodorized (odorless).
Glycolic Acid (AHA): Another widely used AHA, Glycolic Acid has a smaller molecule size than Lactic Acid, allowing for potentially better penetration and exfoliation. It is also effective for pH adjustment. Options include Glycopure™ (Glycolic Acid (AHA) 100% Powder) and Ampho-Glycolic™ (Non-Stinging Glycolic Acid Solution), which is a less irritating liquid form.
L-Ascorbic Acid (Vitamin C): While primarily known for its antioxidant and brightening properties, L-Ascorbic Acid is an acid and can be used to lower pH. However, it is less stable in water-based formulas compared to Lactic or Glycolic Acid and may require careful formulation. Available forms include Vitamin C (L-ascorbic acid) (Ultra-Fine), Vitamin C (L-ascorbic acid) (Fine), and Vitamin C (L-ascorbic acid) (Standard).

Important Considerations for pH Adjustment:

Add Gradually: Always add the acidic ingredient very slowly, a tiny amount at a time.
Measure pH: Use a reliable pH meter to measure the pH after each small addition. Mix thoroughly before measuring.
Target pH: Aim for a final pH of 3.3-3.5 for your BHA leave-on formula. A pH below 3.3 can cause significant skin irritation.

Choose the acidic ingredient based on your preference for additional benefits (like exfoliation from AHAs) and ease of formulation. Remember to handle concentrated acids with care.