Formulation Steps

1. Prepare the Salicylic Acid Solution: Salicylic Acid is not soluble in water alone. As discussed previously and confirmed by the product information, it dissolves well in glycols like Butylene Glycol or Propylene Glycol. In your formula, you have Butylene Glycol.

   • Take the required amount of Salicylic Acid powder and add it to the Butylene Glycol.
   • Stir or mix gently. You may need to warm the mixture slightly (e.g., in a warm water bath, around 40-50°C) to help the Salicylic Acid dissolve completely. Ensure it is fully dissolved and clear before proceeding.

2. Prepare the Water Phase: In a separate container, combine the Water with the other water-soluble ingredients:

   • Methylpropanediol
   • Disodium EDTA
   • Polysorbate-20
   • Camellia Oleifera Leaf Extract (Ensure your specific extract product is water-soluble, like CleanTea™ Liquid).
   • Stir until all ingredients are fully dissolved or dispersed in the water. Disodium EDTA should be mixed in the water phase before other ingredients.

3. Combine Phases: Slowly add the Salicylic Acid/Butylene Glycol mixture from Step 1 into the Water Phase from Step 2 while stirring continuously. Continue stirring until the mixture is uniform.

4. Adjust pH: Your formula contains Sodium Hydroxide, which is used to raise the pH. Salicylic Acid is most effective as an exfoliant at a pH between 3 and 4. However, the pH also affects potential irritation. You will need a pH meter to check the pH of your mixture.

   • Prepare a diluted solution of Sodium Hydroxide (e.g., dissolve the required amount of Sodium Hydroxide in a small amount of water).
   • Add the diluted Sodium Hydroxide solution drop by drop to your main mixture, stirring well after each addition.
   • Continuously monitor the pH with your pH meter until you reach your desired target pH (typically between 3.0 and 4.0 for Salicylic Acid products). Be careful not to add too much, as it's easier to raise the pH than lower it.

Regarding your previous confusion about Allantoin and "remaining water":

• Your current formula does not include Allantoin, so the specific instruction about Allantoin's solubility (0.5% of water) does not apply here.
• The "remaining water" likely referred to adding the bulk of the water after dissolving a key ingredient (like Salicylic Acid) in a smaller amount of solvent, which is essentially what you do in Step 2 by combining the water with the other water-soluble components before adding the Salicylic Acid solution.

This process should help you successfully create your formulation. Remember to use appropriate safety measures when handling ingredients, especially Sodium Hydroxide.