Compatibility and Toner Formulation Issues

Based on the previous discussion:

Ingredient Compatibility with Encapsulated Salicylic Acid

Most of the ingredients you listed are compatible with Encapsulated Salicylic Acid:

• Witch Hazel Extract
• Aloe Vera Extract
• Panthenol (Vitamin B5)
• Coco Wash (PEG-7 Glyceryl Cocoate)

The only ingredient from your initial list that is not compatible with Encapsulated Salicylic Acid is Double Hyaluron Liquid.

Toner Formulation Precipitation

The precipitate observed in your toner formula after two days is likely due to the use of the powder form of Witch Hazel Extract (Product ID 333), which is not easily soluble in water and has been discontinued by the supplier for this reason.

• Encapsulated Salicylic Acid (Product ID 229) itself is water-soluble and should not cause this type of precipitation under normal storage conditions.
• To resolve the precipitation, you can filter the toner using coffee filter paper to remove the insoluble Witch Hazel Extract powder. The remaining liquid should be usable.

Polysorbate 20 for Dissolving Salicylic Acid

Polysorbate 20 (Product ID 175, Product ID 32545) is suitable for dissolving ordinary Salicylic Acid (Product ID 148). However, Encapsulated Salicylic Acid (Product ID 229) and Salicylic Acid EZ (Product ID 7594, Product ID 10947, Product ID 2014, Product ID 7577) are designed to be water-soluble directly, so Polysorbate 20 is not needed for them.

pH of Toner

It is not strictly necessary for a toner to have a neutral pH (5-6). The appropriate pH depends on the purpose of the formula. For a BHA toner containing Salicylic Acid, a slightly acidic pH is beneficial for exfoliation effectiveness. If your formula's pH is already above 3.5, you do not need to adjust it with Sodium Bicarbonate (Product ID 610). Your measured pH of 4.4 is suitable for a BHA toner.

Effectiveness of 1.6% Encapsulated Salicylic Acid

Using 1.6% Encapsulated Salicylic Acid, which is equivalent to 0.5% active Salicylic Acid, is considered effective for addressing mild clogged pores and can be beneficial for your skin type (normal to slightly dry with occasional clogged pores). Lower concentrations can sometimes be more effective than higher ones if high concentrations cause irritation, which reduces ingredient absorption.

Salicylic Acid for Prevention

Salicylic Acid primarily works by dissolving existing clogged pores (comedones). It doesn't prevent their initial formation in the same way that Vitamin A derivatives like Vitamin A Palmitate (Product ID 192) or Adapalene do. However, by dissolving comedones in their early stages, Salicylic Acid can effectively prevent them from developing into larger, more noticeable clogged pores. So, while not a direct preventative mechanism like Vitamin A, its action of dissolving early comedones helps maintain clear skin.