pH Adjustment for Lactic Acid Toner

Based on the information provided:

• Sodium Bicarbonate (ID 610): This is a weak alkali and acts more as a pH balancer. It has limited solubility in water (around 7-8%) and cannot make a formula significantly alkaline. It is suitable for very mild pH adjustments.
• Triethanolamine (ID 139): This is a weak alkali suitable for adjusting pH when a slight increase towards alkaline is needed.
• Sodium Hydroxide (ID 636): This is a strong alkali suitable for significant pH adjustments from very acidic to alkaline. It is corrosive and requires extreme caution.

Your understanding that Sodium Bicarbonate is for mild acidity and Triethanolamine for stronger acidity is correct, keeping in mind Sodium Bicarbonate's solubility limit.

For a toner containing Lactic Acid (ID 170):

• For personal use: You can choose not to adjust the pH to maintain exfoliation effectiveness. An alternative is to neutralize your skin after application.
• For commercial products: pH adjustment is required (e.g., min pH 3.5). The choice of base depends on the Lactic Acid concentration and target pH. Higher Lactic Acid concentration may require a stronger base like Sodium Hydroxide or more of a weaker base like Triethanolamine.