Feedback on Your Sunscreen Formula and Related Questions

Hello,

Thank you for sharing your sunscreen formula and questions. It's great that you are experimenting with formulations for your product line.

Regarding the formula you provided:

1. DI Water 73%
2. Pro Polymer™ (Gel Maker) 1%
3. Phenoxyethanol SA (Optiphen Plus) 1%
4. Titanium Dioxide 15nm Liquid 25%

The issue you encountered with the texture resembling curdled milk is likely due to the incompatibility of the ingredients and the type of emulsion system you are trying to create.

The Titanium Dioxide 15nm Liquid is specifically designed for water-in-oil (W/O) emulsion systems and is not recommended for oil-in-water (O/W) systems. It also states that it cannot be used in formulas containing electrolytes. Your formula has a very high water content (73%) and uses Pro Polymer, which is a water-phase thickener. This suggests you are attempting to create an O/W emulsion or a gel, which is incompatible with the recommended use of this specific Titanium Dioxide dispersion. The curdling is a sign that the Titanium Dioxide is not properly dispersing or emulsifying in your chosen system.

Now, let's address your specific questions:

Your Questions Answered

1. Temperature during mixing: The instruction to heat to 70°C on the Titanium Dioxide 15nm Liquid page refers to an example formula which is a water-in-oil emulsion using Cyclomethicone. In that specific W/O system, heating helps with the dispersion. For your formula, the incompatibility is the primary issue, not necessarily the exact temperature you reached. However, it's important to note that Phenoxyethanol SA (Optiphen Plus) should be added at temperatures below 60°C to maintain its effectiveness. Exceeding 70°C might degrade some ingredients, but the main problem here is the ingredient compatibility.

2. Heating other sunscreen ingredients: The need for heating depends on the specific sunscreen ingredient and how it is dispersed or solubilized. Some dispersions or solid powders require heat to incorporate properly into certain phases, while others can be added at room temperature. Always check the specific product's instructions.

3. Titanium Dioxide vs. Zinc Oxide: Both are physical sunscreen filters that work by reflecting and scattering UV rays.

   • Titanium Dioxide primarily protects against UVB and short-wave UVA.
   • Zinc Oxide provides broad-spectrum protection, including excellent protection against long-wave UVA.
     For comprehensive broad-spectrum protection (UVA and UVB), it is highly recommended to use both Titanium Dioxide and Zinc Oxide in your formula. Regarding the white cast ("หน้าวอก"), both can cause it, especially at higher concentrations or with larger particle sizes. However, using nano-sized or specially coated/dispersed versions (like the Titanium Dioxide 15nm Liquid or Zinc Oxide 35nm Liquid/200nm EasyDisperse) significantly reduces the whitening effect compared to non-nano or uncoated versions.

4. Color additives to avoid white cast: To counteract the white cast from physical sunscreens and achieve a natural look, you can incorporate cosmetic pigments or use a foundation/BB/CC cream base designed for tinting. These can be added to adjust the color of the sunscreen to match various skin tones.

5. Fragrance recommendation: You can use cosmetic-grade fragrance oils in your sunscreen formula. Choose a scent that aligns with your product's desired profile. Add the fragrance during the final step of your formulation, ensuring the temperature is below 60°C (due to the preservative, Phenoxyethanol SA).

Tips for Achieving Your Desired Sunscreen Characteristics

To achieve the characteristics you desire for your product (SPF 40-50 / PA+++, lightweight, non-greasy, waterproof, natural look, suitable texture, ease of mixing, cost-effectiveness):

• SPF/PA: Use appropriate concentrations of both Titanium Dioxide and Zinc Oxide. Refer to guidelines or perform testing to confirm the SPF/PA level.
• Texture and Feel: Select suitable emulsifiers and thickeners. For a lightweight, non-greasy feel, consider using silicones or light esters in the oil phase (if making a W/O or O/W emulsion) and choose thickeners that provide the desired viscosity without tackiness.
• Waterproof: Incorporate film-forming polymers or specific water-resistant waxes into your formula.
• Natural Look: Use nano or coated physical sunscreens and add skin-tone colored pigments or a tinting base.
• Ease of Mixing: Using pre-dispersed liquid forms of Titanium Dioxide and Zinc Oxide (like the 15nm Liquid or 35nm Liquid) can simplify the mixing process compared to using powders.
• Cost-effectiveness: Evaluate the cost of different ingredient options and their required usage rates.

Given the issues with your current formula and the type of Titanium Dioxide dispersion used, you might need to revise your formula significantly, potentially changing the emulsion system or selecting different types of physical sunscreen dispersions that are compatible with a high water phase or the desired O/W system.

I hope this detailed feedback helps you in developing your sunscreen product!