How Do Sunblocks and Sunscreens Compare?

Overview

Objectives/Goals The objective of my project is to determine if sunblocks are more effective than sunscreens in blocking ultraviolet rays in sunlight. I believe that the three brands of sunblock will block more UVA and UVB rays than the three brands of sunscreen. Methods/Materials Samples of three brands of sunblock and three brands of sunscreen were weighed and each spread over a separate 5 cm X 5 cm area on a clear plastic folder. Printing-out paper (photosensitive paper) was inserted in the plastic folder and it was placed in the sun for five minutes. The exposed printing-out paper was rinsed, then submerged in Kodak Fixer. This process was repeated for four trials. The developed paper was compared to a gradation scale. Results The sunblocks were more effective than the sunscreens when they both had the same Sun Protection Factor (SPF) number. Conclusions/Discussion My conclusion is that sunblock ingredients do block out more ultraviolet rays than sunscreens. Sun Protection Factor (SPF) number is a reliable indicator of the effectiveness of sunscreens, but it is not a reliable indicator of the effectiveness of sunblocks.

Awards (1)

• Category Award

Competition history

• CSEF 2005 Materials Science (Junior Division Only) · Entry J1129

Resources

• CSEF project summary ↗

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