Formula Review: Waterproof Sunscreen Lotion SPF 50 PA++

Based on the ingredients and percentages provided, this formula for a waterproof sunscreen lotion with SPF 50 PA++ appears suitable.

• SPF Protect Ultra™ II (15%): According to the product information, using SPF Protect Ultra™ II at 15% can achieve SPF 50, PA++, which aligns with your target protection level.
• Water-in-Oil EZ™ (4%): This is a suitable water-in-oil emulsifier for sunscreen formulations and contributes to the water resistance and durability of the lotion on the skin. The usage rate of 4% is within the recommended range.
• Phenoxyethanol SA (1%): This preservative is used within the recommended concentration range and should provide adequate preservation for the formula.

Mixing Steps:
The mixing steps you outlined generally follow the recommended procedure for creating a water-in-oil emulsion, particularly the crucial step of adding the water phase to the oil phase gradually while mixing.

Suggestion for Improvement:
The product description for Water-in-Oil EZ™ suggests that adding 1% Magnesium Sulfate can help increase the stability of water-in-oil emulsions and reduce the chance of separation. You might consider adding this to your formula for enhanced stability.

Overall, the formula is well-structured and uses appropriate ingredients for the desired product. Considering the addition of Magnesium Sulfate could further improve its stability.