Using Citric Acid for pH Adjustment in Cold Process Soap
Question
Can Citric Acid be used to help reduce the pH in cold process soap, and if so, how should it be used safely, and what are its effects and limitations compared to natural aging?
Answer
Yes, you can use Citric Acid to help slightly reduce or buffer the pH in cold process soap.
It is crucial to dissolve the Citric Acid completely in the water before you add the Sodium Hydroxide (lye).
Do NOT add Citric Acid to the water after the lye has been added or is dissolving, as this can cause a strong and potentially dangerous reaction.
The Citric Acid reacts with the Sodium Hydroxide to form Sodium Citrate.
While Citric Acid can help slightly, achieving a specific pH like 9.0 might not be guaranteed, and significant pH reduction in lye-based soap is limited without affecting the soap's hardness. Aging the soap for several weeks is also an essential step for the saponification process to complete and for the pH to naturally decrease over time.