Sunscreen is a substance that helps protect the skin from the sun's harmful rays. Sunscreens reflect, absorb, and scatter both ultraviolet A and B radiation to provide protection against both types of radiation. Using lotions, creams, or gels that contain sunscreens can help protect the skin from premature aging and damage that may lead to skin cancer ("NCI Dictionary of Cancer Terms", 2021). This study demonstrates basic knowledge about sunlight and sunscreen including kinds of sunlight, the mechanism and evaluation methods of sunscreen, et al. Experiments were carried out to investigate three variables (solvent, temperature, UV filter) to test the relationship between the changing factors of sunscreen and the relative influences on sunscreen’s effectiveness. Key results indicated that temperature has the least effect on the effectiveness of sunscreen, which means the change of temperatures causes the SPF to change insignificantly. Solvents with different polarity can lead to different SPF, with polar and non-polar solvents absorbing more UV, and semi-polar solvents have the weaker ability to absorb UV. Different types of UV filters cause various changes in the effectiveness of sunscreen. The key findings in this study provided insights for the formulation and effect evaluation of the sunscreen for consumers. Also, it could be useful for consumers to choose the sunscreen that is the best fit for them.

Yizhu Chen. Formula preparation of sunscreen (experimental phenomenon and property description) and evaluation of its efficacy. Academic Journal of Materials & Chemistry (2024) Vol. 5, Issue 3: 43-50. https://doi.org/10.25236/AJMC.2024.050307.

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