Explanation for Condensation in Sunscreen Cream

The condensation observed inside the pump bottle above the cream is likely due to a temperature difference during the manufacturing and packaging process.

1. Temperature Difference: You mentioned storing ingredients in the refrigerator and using them immediately to mix the cream at room temperature, then bottling it right away. When the cold cream is placed into a bottle at room temperature, the air inside the bottle warms up and can hold more moisture. Water from the cream (which is an oil-in-water emulsion) can also evaporate into this space. As this warm, moist air touches the cooler surface of the bottle (initially cooled by the cream), the water vapor condenses into liquid droplets.

Is the Cream Still Usable?

Yes, the cream is generally still usable. The condensation indicates a small amount of water separation, which can happen in oil-in-water emulsions, especially with temperature fluctuations. However, significant water loss over time could potentially affect the stability and intended concentration of ingredients, including the SPF protection. If the amount of condensation is minimal, it should not significantly impact the product's performance for typical use.

How to Prevent Condensation in the Future

To prevent this issue, follow these steps:

1. Bring Ingredients to Room Temperature: Before mixing, allow any ingredients stored in the refrigerator to sit at room temperature until they reach ambient temperature.
2. Ensure Cream Reaches Room Temperature: After mixing, if the cream is still cool, let it sit for a while to reach room temperature before filling it into bottles.
3. Thorough Mixing: Ensure your mixing process creates a stable emulsion. Proper emulsification helps keep the water phase well-incorporated within the cream, reducing the tendency for water to separate and evaporate.

By minimizing temperature differences during preparation and packaging, you can reduce the likelihood of condensation forming inside the bottle.