Sunscreen Formulation Issues (Smell and Clogging)

Subject: Sunscreen Formula Issues (Smell and Clogging)

Dear Customer,

Thank you for providing details about your sunscreen formulation issues. We understand you are experiencing two main problems: an unpleasant odor developing after 1-2 weeks and clogging of the airless pump bottle after about 3 months.

Regarding the Clogging Issue:
Based on your formula and the staff's feedback, the clogging issue in your first formula (SPF Protect Ultra 20%, Light Cream Maker 1%, LipidSoft Dry 10%, etc.) is likely due to the emulsifier, Light Cream Maker. Light Cream Maker is designed for formulas with a lower oil phase. In your problematic formula, the total oil phase (SPF Protect Ultra + LipidSoft Dry + Vit E) is around 30.5%, which exceeds the capacity of Light Cream Maker to maintain a stable emulsion over time. This instability causes the formula to separate or clump, leading to the "glue-like" substance that clogged your pump. Your previous formula, which used LipidSoft CC 5% (total oil phase around 25%) and did not have this issue, supports this explanation, as the oil phase was lower.

Regarding the Smell Issue:
You noted that the unpleasant smell occurred with the formula containing LipidSoft Dry and Vit E, but not with the previous formula containing LipidSoft CC and no Vit E. While the staff response focused on the clogging, the change in odor could be related to the ingredients that differed between the two formulas.

• LipidSoft Dry (Isononyl Isononanoate) and LipidSoft CC (Cetearyl Ethylhexanoate) are different emollients. Their inherent smell or stability can differ.
• Vitamin E (Tocopheryl Acetate), while often used as an antioxidant, can sometimes degrade or interact with other ingredients, potentially contributing to an off-odor, especially if the raw material quality is not optimal or if the formula lacks other stabilizing agents.

To mitigate the smell issue in the future, ensure all ingredients are fresh and stored correctly. If using Vitamin E, consider its source and quality, and ensure the overall antioxidant system in the formula is robust.

Regarding Your Proposed Formula with Milk Lotion Maker:
You proposed a new formula using Milk Lotion Maker to address the emulsification issue:

• LipidSoft 20%, Cyclomethicone 10%, Dimethicone 7%, ZnO 10%, TiO2 5%, Milk Lotion Maker 5%, Phenoxyethanol 1%, Water 42%.

The staff correctly advised that Milk Lotion Maker requires the water phase to be at least 60% of the total formula. Your proposed formula has only 42% water (and 58% oil/silicone/powder/emulsifier/preservative).

To use Milk Lotion Maker successfully, you need to adjust the percentages so that the water content is 60% or higher. This means the total percentage of LipidSoft, Cyclomethicone, Dimethicone, ZnO, TiO2, Milk Lotion Maker, and Phenoxyethanol must be 40% or less.

Here is an example of how you could adjust your proposed formula to meet the 60% water requirement while keeping the same relative proportions of your non-water ingredients (or adjusting them based on desired feel/SPF):

• Example Adjusted Formula (Water >= 60%):*

• LipidSoft: 10%

• Cyclomethicone: 8%
• Dimethicone: 6%
• ZnO: 7%
• TiO2: 3%
• Milk Lotion Maker: 5%
• Phenoxyethanol: 1%
• Water: 60%
• Total: 100%

(Note: The total of non-water ingredients is 40%, allowing for 60% water).

The mixing instructions you provided for the Milk Lotion Maker formula (heating the oil phase to 80C, adding Milk Lotion Maker, then sunscreen powders, blending, and slowly adding water while blending) are generally correct for this type of emulsifier.

Alternatively, as the staff suggested, if you need a high oil/powder phase (like your original formula), consider using a different emulsifier better suited for high oil loads or W/O emulsions, such as Water-in-Oil EZ (requires high-speed blending and will result in a water-resistant formula).

We hope this explanation helps you troubleshoot your formulation.

Sincerely,
[Your Name/MySkinRecipes Team]