Citric acid is a buffering agent which is used to correct the pH of cosmetics in order to match the pH of human skin and hair. Our skin has a pH of around 5.5, and our hair has a pH of 4.5. You will use this citric acid solution when the pH of your homemade cosmetics test too high, and you need to reduce the pH.
You cannot use this citric acid solution in anhydrous (oil-based) products, since citric acid is water-soluble. You can only use this citric acid solution to correct the pH of emulsions and water-based products like lotions, facial toners, conditioner, and surfactant cleansers like shampoo.
Citric acid is a weak organic acid that occurs naturally in citrus fruits. Citric acid is used in the food, cosmetic and pharmaceutical industries for various purposes including as a flavourant, buffering agent (pH correcting), stabilizer, preserving agent and disinfectant.
How to use:
- Test the pH of your product at room temperature using pH strips or a digital pH meter.
- If the pH is above the desired target, then thoroughly blend in a few drops of the citric acid solution at a time (start with 5 drops).
- Re-test the pH of your product, and take note of the change in pH.
- If you still need to achieve a lower pH, continue to add drops of the citric acid solution and retest until the target pH is achieved.
Recipes by Natural Nerd:
Ingredients: Citric acid (25%), pharmaceutical grade distilled water (75%).
Packaging: Glass bottle with a glass pipette that is attached to an HDPE plastic lid. Paper label.