Formulation Advice for Silky Serum Base Plus

It appears the separation you are experiencing with your cream formulation using Silky Serum Base Plus and 5% oil is likely due to the absence of a key stabilizer recommended for this base.

The description for Silky Serum Base Plus explicitly states that adding 1-2% Magnesium Sulfate is recommended to help increase the stability of the formula and prevent layer separation. Magnesium Sulfate acts as an emulsion stabilizer, particularly effective in water-in-oil (W/O) systems, which is the type of emulsion Silky Serum Base Plus is designed for (as indicated by its INCI ingredients like Lauryl PEG-9 Polydimethylsiloxyethyl Dimethicone, a W/O emulsifier).

Adding Magnesium Sulfate at the recommended usage rate (0.1-2%, with 1% being a common recommendation) in the water phase, as described for Magnesium Sulfate, and incorporating it into your formula following the mixing instructions for Silky Serum Base Plus (adding it in the last step and blending until dissolved) should significantly improve the stability and prevent the oil from separating.

Regarding alternatives to Magnesium Sulfate:
Magnesium Sulfate is specifically recommended by the manufacturer for use with Silky Serum Base Plus to enhance stability. While other W/O stabilizers exist, their compatibility with the specific composition of Silky Serum Base Plus is not guaranteed and would typically require testing to ensure they perform effectively without negatively impacting the formula's texture or stability. Therefore, the most reliable solution based on the product information is to incorporate Magnesium Sulfate as recommended.

Also, ensure you are following the recommended mixing procedure for Silky Serum Base Plus, particularly adding the water phase gradually to the base while stirring, as incorrect mixing can also contribute to instability.

In summary, the most direct and recommended solution to prevent separation in your formula is to add 1-2% Magnesium Sulfate.