Determining the effectiveness of different sunscreen products in blocking ultraviolet (UV) radiation
Materials required for the science fair project are as follows:
- 16 sheets of glass (approximately 550 mm in length x 550 mm wide). These may be obtained from your local hardware store or home depot
- 5 brands of sunscreen with SPF 15
- 5 brands of sunscreen with SPF 30
- 5 brands of sunscreen with SPF 50
- 1 UV meter to measure the UV index readings. Check with the laboratory at your school. Relatively cheap meters are sold on Amazon.com.
- 1 bottle of glass cleaner
- A box of disposable gloves (at least 15 gloves)
- 1 piece of cloth
- A pair of thick safety gloves
- 1 wooden box with no covering on the top (approximately 500 mm in length x 500 mm wide)
1. The independent variable in this science fair project is the brand of the sunscreen used and their respective SPF values. The dependent variable is the level of UV index detected after applying the sunscreen. The amount of UV radiation present is measured using the UV meter. The constants (control variables) are the time at which the measurements are taken, the intensity of sunlight on the day of the experiment, and the geological location of the testing area.
2. Divide the sunscreen products into 3 groups according to their SPF value. Within each group, label each brand as A, B, C, D or E accordingly. Next, clean the 16 sheets of glass on both sides using the glass cleaner to remove any dirt on the surface. Label 15 sheets of glass A, B, C, D, E, followed by their respective SPF value. Label one sheet of glass as “None” for the control group.
3. Coat the glass sheets with a layer of the sunscreen according to is label. Use the same amount of sunscreen for each sheet of glass, ensuring that the entire sheet is covered with a thin film of sunscreen. Do not use excessive amounts. Wear the gloves and use your fingers to spread the sunscreen. Ensure that you change gloves before spreading the sunscreen for the next sample.
4. Place the wooden box in a suitable open area that has direct sunlight. There should be no shadows on the box. Place the UV meter inside the box, and record the UV index reading in the table below. Next, cover the box using the sheet of glass labeled “None”, and record the UV indexreading again in the table below. This is the control group reading. Be extremely careful when handling the glass and make sure you use the safety gloves at all times.
5. The sheets of glass with the sunscreen coating will now be tested. Place the glass sheets one at a time on the box and record the UV index measurement. Remember to remove each sheet of glass from the box after measuring its UV index. Record all the measurements in the table given below.
Be extremely careful when handling glass. Adult assistance is required. You should also protect all participants from exposure to the sun. Use sunscreen/umbrellas and ensure that you are properly hydrated