Physical Sunscreen Formulation Feedback

Based on your goal to create a physical sunscreen similar to Smooth-E Physical White Sunscreen SPF 52 and your proposed formula, let's review the details.

Comparing your formula concept to the initial Water-Base and Silicone-Base examples, your approach using Water, LipidSoft Lite, Light Cream Maker, Zinc Oxide, Titanium Dioxide, WaterGuard, and considering Dimethicone aligns more closely with the type of mixed-phase system discussed previously. This system, utilizing an emulsifier like Light Cream Maker, can effectively incorporate both water and oil/silicone components to disperse physical filters and achieve desired textures and properties, similar to what might be used in a product like Smooth-E.

Here is feedback on your specific questions about the proposed formula:

• WaterGuard™ Usage Percentage: For sunscreen products requiring water/sweat resistance, a usage rate of 2-5% for WaterGuard™ is generally recommended. You can start within this range and adjust based on the level of water resistance you want to achieve and the results of your own testing.

• Dimethicone Usage and SiliSolve: Adding 1-3% Dimethicone to your formula is feasible. Based on the properties of Light Cream Maker, it is capable of emulsifying silicone at these levels (up to 10-20%), so you do not need to use SiliSolve to incorporate this amount of Dimethicone.

• Ingredient Overlap: You asked about potential overlap in properties among WaterGuard™, Beige Iron Oxides EasyMix™, Silk Mica Powder (Matte), and Dimethicone, specifically regarding water resistance and makeup longevity.

  • WaterGuard™: Primarily provides water and sweat resistance by forming a film.
  • Dimethicone: Contributes to a smooth skin feel, can enhance water resistance, and helps makeup adhere better by forming a film.
  • Beige Iron Oxides EasyMix™: Provides color tint and coverage. As a powder, it helps absorb oil and improves makeup adherence.
  • Silk Mica Powder (Matte): Acts as a filler, improves texture and spreadability, provides a matte finish, and helps makeup last longer by absorbing oil.
    There is some functional overlap, particularly between WaterGuard™ and Dimethicone for water resistance and film-forming, and between the powders (Iron Oxides and Silk Mica) for coverage and makeup adherence. However, each ingredient also offers unique benefits contributing to the overall feel, appearance, and performance of the product. Whether you need to remove any depends on the specific balance of properties you desire in your final formulation.

• Suitability for Very Sensitive Skin: All the ingredients you listed generally have a very low potential for causing irritation. Among them, Phenoxyethanol has the relatively highest chance of irritation, but it is still considered a low-risk preservative when used within recommended concentrations (typically 0.5-1.0%). Overall, the ingredients chosen are generally considered suitable for sensitive skin, but individual sensitivities can vary.

Remember that successful formulation often requires testing and adjustment to achieve the desired texture, stability, SPF/PA rating, and performance characteristics.