The challenge you face is that CysWhite™ (Cysteamine HCL) (ID: 9233) is a water-soluble powder, meaning it is not directly soluble in oil. However, your decision to use an anhydrous (water-free) formula is correct for maximizing the product's shelf-life and stability.

To successfully incorporate this water-soluble active into an anhydrous face oil serum, you need a cosolvent that is miscible with both the CysWhite™ and the oil base.

The most suitable ingredient for this purpose is Ethoxydiglycol (e.q. Transcutol) (ID: 137).

Formulation Method for Anhydrous Face Oil Serum

Ethoxydiglycol is an excellent solvent that is soluble in water, glycols, and natural oils, making it the perfect bridge between your active powder and the oil base.

Steps:

1. Prepare the CysWhite™ Solution: Dissolve the required amount of CysWhite™ (Cysteamine HCL) powder (typically 1-5%) directly into the Ethoxydiglycol. Stir until the powder is completely dissolved and the solution is clear.
2. Incorporate into Oil Base: Add the CysWhite™/Ethoxydiglycol solution to your chosen oil base (e.g., Jojoba Oil, Squalane, or other natural oils). Stir well until the entire mixture is homogenous and clear.

Key Formulation Considerations

• Ethoxydiglycol Usage Rate: For leave-on products like a face oil serum, the usage rate for Ethoxydiglycol is currently restricted to not more than 2.6%. Ensure your total formula respects this limit.
• Total Active Concentration: CysWhite™ is typically used at 1-5%.
• Odor Control: CysWhite™ has a strong, unique odor. To mitigate this, consider adding an odor absorber like Odor-Kill (mentioned in the product description) or a small amount of fragrance/essential oil, ensuring they are compatible with the anhydrous oil base.
• Stability: While the anhydrous formula is stable, Cysteamine HCL is sensitive to oxidation. Ensure the final product is stored in an opaque, air-tight container, and consider adding a small amount of a suitable antioxidant (if compatible with the oil base) to further protect the formula.