Information and Recommendations for Your Formulation Questions

Thank you for your detailed questions regarding packaging, formulations, and ingredients. Here is a summary of the information and recommendations based on your queries and the available data:

Product Packaging

I understand your concern about the old pump bottle packaging causing product to leak around the edges when pressed, and your preference for the new opaque bottle. The staff has acknowledged this issue with the pump bottles and is looking into solutions. Currently, selecting a specific packaging type when ordering may not be possible, but your feedback is valuable and has been noted by the team.

Sunscreen Project and Ingredients

Regarding a potential project to make your own sunscreen and testing at a university lab, I do not have specific information about this project. However, I can provide details on the sunscreen ingredients you mentioned and some found in the Spectraban SC product you use.

Common and effective UV filters include:

• Tinosorb (BEMT and Bisoctrizole): These are highly stable organic (chemical) filters that provide broad-spectrum protection against both UVA and UVB rays. They work well with other sunscreens, including physical filters like Zinc Oxide and Titanium Dioxide.
• Mexoryl (Na-Ecamsule and Drometrizole Trisiloxane): These are also stable organic filters. Na-Ecamsule (Mexoryl SX) is water-soluble and primarily protects against UVA. Drometrizole Trisiloxane (Mexoryl XL) is oil-soluble and offers broad-spectrum UVA/UVB protection.
• Zinc Oxide: A physical filter that provides broad-spectrum protection, particularly effective against UVA rays. Different forms are available, including micronized and transparent dispersions, which can affect the product's texture and whiteness on the skin. It is considered safe as it is not absorbed into the skin.
• Titanium Dioxide: Another physical filter that primarily protects against UVB and short-wave UVA. Like Zinc Oxide, it comes in various forms, including transparent versions that minimize the white cast. For comprehensive broad-spectrum protection, it is often used in combination with Zinc Oxide.
• DHHB (equivalent to Uvinul A Plus): An organic filter that effectively blocks UVA rays and is highly stable. It can be used with physical filters like Zinc Oxide and Titanium Dioxide.

Combining different types of UV filters (chemical and physical) is often recommended to achieve broad-spectrum protection across the entire UVA and UVB range.

Azelaic Acid Storage

While most chemical ingredients are sensitive to light and heat, brief exposure is unlikely to cause immediate spoilage. However, to maintain the stability and efficacy of Azelaic Acid over the long term, it is best to store it in a dark place away from direct sunlight and heat.

Homemade Vitamin C Serum

Your formula of 20% Vitamin C, 40% Ethoxyldiglycol, and 40% Water, made weekly, should help maintain freshness. However, as noted in the forum, it is crucial to check the color before each use. If the serum turns yellow, it indicates oxidation, and it should be discarded as it may become pro-oxidant. The recrystallization of Vitamin C on the cap edges is likely due to the evaporation of water and ethoxydiglycol upon exposure to air, leaving the solid Vitamin C behind.

Cleansing Methods

The three cleansers you mentioned (Acne Aid Liquid, Acne Aid Gentle, Boots Expert Sensitive Gentle Cleansing Wash) and your suggested Lauryl Glucoside formula are generally considered gentle. The best choice depends on your skin's individual response. As noted, Acne Aid Liquid may be drying for some and contains fragrance and Myristic acid, which can be comedogenic for certain individuals.

For effectively removing sunscreen, especially water-resistant formulas like Spectraban SC which contains silicones and UV filters, a single wash with a gentle cleanser might not be enough. While you prefer to avoid oil cleansers, a first cleansing step is often beneficial. Alternatives to oil cleansers for this first step include micellar water, cleansing milk, or a non-oil-based cleansing balm or gel. Following this with a gentle water-based cleanser (like the ones you listed or your Lauryl Glucoside formula) as a second step (double cleansing) is a more thorough method for removing sunscreen and impurities without necessarily needing an oil-based product.