Mixing Active Ingredients into Pre-made Cream Bases

Subject: Mixing Active Ingredients into Pre-made Cream Bases

Here's some guidance on incorporating active ingredients into pre-made cream bases like soft cream, cica, or sleeping masks:

1. Should you heat the cream base?

   • Generally, no. Pre-made cream bases are finished emulsions. Heating them can destabilize the emulsion, causing it to separate. It can also degrade heat-sensitive ingredients already present in the base.
   • Active ingredients should typically be incorporated at room temperature or slightly above, depending on the active itself, but the base should not be significantly heated.

2. Limitations of active ingredients (water/oil) and maximum dose:

   • Type of Active:
     • Water-soluble actives: These should usually be dissolved in a minimal amount of distilled water or a suitable solvent (like a small percentage of glycerin or propanediol) before slowly adding them to the cream base while stirring gently.
     • Oil-soluble actives: These should usually be dissolved in a minimal amount of a compatible oil or solvent before slowly adding them to the cream base while stirring gently.
   • Maximum Dose:
     • Pre-made bases have a limited capacity to incorporate additional ingredients without compromising their stability, texture, and preservation system.
     • Adding too much liquid (water or oil phase from the actives) or too many solids can break the emulsion, make the product too thin or thick, or affect its feel and shelf life.
     • As a general rule, the total amount of added active ingredients and their solvents/carriers should be kept relatively low, often not exceeding 5-10% of the total formulation. However, this is a rough guideline and depends heavily on the specific base and active.
     • Always start with a small test batch to check for stability (no separation), texture changes, and compatibility.

General Tips:

• Add actives slowly and mix gently but thoroughly to ensure even dispersion without incorporating too much air or stressing the emulsion.
• Consider the pH of the active ingredient and how it might affect the pH of the final cream. Significant pH changes can also destabilize the base or affect the efficacy/stability of other ingredients.
• Be mindful of the preservation system in the base. Adding large amounts of unpreserved ingredients or altering the pH significantly can compromise preservation, potentially leading to microbial growth.