How to Choose and Use pH Adjusters in Cream Formulations

Choosing the right pH adjuster for your cream depends on whether you need to lower or raise the pH level. Most skin care products aim for a pH range of 5.0 to 6.5, which is close to the skin's natural acidity.

1. To Lower pH (Acidifiers)

If your cream is too alkaline (high pH), you can use these ingredients:

• Citric Acid (Anhydrous, Natural): The most common and cost-effective choice. It is derived from natural fermentation. It's best to dissolve it in a small amount of water before adding it to the formula for even distribution.
• Lactic Acid (AHA) 90% Deodorized (odorless): A great alternative that also provides moisturizing benefits and gentle exfoliation. The deodorized version is recommended to avoid a sour smell in your final product.

2. To Raise pH (Alkalizers)

If your cream is too acidic (low pH), you can use these ingredients:

• Triethanolamine 99% (TEA): The most widely used alkalizer in cosmetics. It is easy to use but should generally not exceed 2.5% of the total formula.
• AMP (2-MINO-2-METHYL-1-Propanol) 95% (Deodorized): Offers better stability than TEA and is particularly effective in formulas containing high alcohol content or those requiring high clarity.
• Sodium Hydroxide (Caustic Soda): A very strong base. It is typically prepared as a 10-20% solution in distilled water before use to allow for precise, incremental adjustments.

How to Adjust pH in a Cream

1. Prepare a Solution: For solid adjusters like Citric Acid or strong bases like Sodium Hydroxide, always dissolve them in distilled water first to create a working solution.
2. Adjust at the Final Stage: pH adjustment is usually the last step after the cream has been fully emulsified and cooled.
3. Add Incrementally: Use a dropper to add the adjuster very slowly, one drop at a time, while stirring thoroughly.
4. Measure Frequently: Use a calibrated pH meter or high-quality pH strips to check the value after each addition until you reach your target range.

Safety Precautions

• Handle with Care: Concentrated pH adjusters can be corrosive. Always wear gloves and eye protection.
• Avoid Direct Contact: Never apply concentrated adjusters directly to the skin.
• Check Compatibility: Some thickeners or active ingredients may lose stability if the pH changes too drastically. Always monitor the texture of your cream during adjustment.