Adjusting pH in an Acidic Toner Formula

Question

Hello, I'm currently making a Toner formula. When I measured the pH, it came out very acidic, so I'd like to know how to adjust acid-alkaline:

Can I use Triethanolamine?
Or should I use Sodium Hydroxide?
If using Sodium Hydroxide, what is the ratio for dissolving it in water?

Thank you.

Answer 1

Both Triethanolamine and Sodium Hydroxide can be used to adjust the pH of your toner formulation upwards (make it less acidic/more alkaline).

Here's a breakdown of each:

Triethanolamine 99%: This is a high-purity type suitable for cosmetic formulations. It is used to increase alkalinity (increase pH value).
- Usage Rate: 0.1-2.5%. Do not use more than 2.5%.
- Mixing Method: Add during the step where you need to adjust the pH.
- Caution: Do not touch the skin directly. If unsure, check information before use.
Sodium Hydroxide: Also known as Caustic Soda, it is commonly used to increase the pH of cosmetic formulations.
- Usage Rate: 0.1-5%. Do not use more than 5%.
- Mixing Method: Add during the process to adjust the pH.
- Caution: Avoid inhaling fumes when adding to water. It is easily moistened, so keep it sealed properly.

Regarding Sodium Hydroxide dissolution:

Sodium Hydroxide dissolves easily in water. For adjusting pH in a formulation, it's best practice to prepare a dilute solution first rather than adding the solid directly. A common concentration is a 10% solution.

To make a 10% Sodium Hydroxide solution:
Mix 10 grams of Sodium Hydroxide with 90 grams of water.

Add this dilute Sodium Hydroxide solution drop by drop to your toner formulation, stirring well and checking the pH frequently with a pH meter or pH strips until you reach your desired pH level. Always add slowly, as pH can change rapidly, especially near the neutral point.

Answer 2

Update (2026-05-17): For a modern leave-on toner, Tromethamine (TRIS) or L-Arginine are now often recommended as the preferred choices for raising pH due to their excellent skin compatibility and low odor. While Triethanolamine remains a usable option, it requires stricter control of formulation conditions to avoid the potential formation of nitrosamines.

Sodium Hydroxide is still a reliable technical pH adjuster but should always be used as a dilute solution (10% w/w, or even 1% w/w for small batches) to prevent overshooting your target. When preparing a Sodium Hydroxide solution, always add the flakes slowly into water (never water into the flakes) and allow the solution to cool before use.

Crucially, do not automatically adjust your toner to a neutral pH of 7. Instead, determine your target pH based on the specific requirements of your active ingredients and your preservative system to ensure the final product remains effective and stable.

References:

Fiume MM et al. Safety Assessment of Triethanolamine and Triethanolamine-Containing Ingredients as Used in Cosmetics. Int J Toxicol. 2013.
Becker LC et al. Safety Assessment of Tromethamine, Aminomethyl Propanediol, and Aminoethyl Propanediol as Used in Cosmetics. Int J Toxicol. 2018.
Burnett CL et al. Safety Assessment of Inorganic Hydroxides as Used in Cosmetics. Int J Toxicol. 2021.
Lambers H et al. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int J Cosmet Sci. 2006.