M6th - Sunscreen project

Title:

Do Different SPF's Make A Difference When Using Same Brand Sunblock? Does Price Affect The Way Sunblock Works?

Student Researcher: Laura Barkin School: Edgemont Jr/Sr. High School White Oak Lane Scarsdale New York 10583 Grade: 7 Teacher: Ms. Russo I.

Statement of Purpose and Hypothesis:

I wanted to know if SPF matters when you buy sun block. For example, does a CVS brand 30 sunblock work better than a CVS brand 15 sunblock? I also wanted to know if higher priced sunblock works better than lower priced sunblock of the same SPF? My hypothesis was that the higher the SPF the better it would protect and that higher priced sun block would work better than lower priced.

II.

Methodology:

For the first part of my project, I bought four types of CVS brand sunblock. Each of these sunblocks had a different SPF. The different SPF's were 30, 15, 8, and 4. I also bought a pack of developing paper at a local photography store and 4 clear plastic report folders. I then got some distilled water and a dish pan. I asked my science teacher for sodium thiosulfate.

The first thing I did was divide the report folder in 4 equal squares using masking tape. I then labeled each sun block 1, 2, 3, or 4. I labeled each square 1, 2, 3, or 4. I then applied the numbered sunblock to the appropriate square. I put the same amount of sunblock on each square making it as even as possible.

After I put the sunblock on, I dimmed the lights very low. I carefully took out a piece of developing paper, making sure to close the case afterwards to keep the light away from the other sheets. I put the developing paper, glossy side up, inside the report. I then quickly took it outside on the driveway where it was very sunny. I left it there for exactly 5 minutes. While it was in the sun I made the mixture of the sodium thiosulfate and distilled water in the dish pan. When the 5 minutes was up I brought the report folder back inside to the semi-darkened room. There I carefully took out the developing paper from the report folder and layed it glossy side down in the mixture for three seconds. Then I immediately rinsed it with cold water and let it dry for 15 minutes. When it was dry I observed it.

For the second part of my experiment I did the exact same thing except I used the sun blocks that varied in price, but had the same SPF. My controlled variables was that I used the same amount of light, same dish pan, and the same mixture of sodium thiosulfate. My manipulated variables were the different sunblocks with the different SPF's or the differently priced sunblock. The responding variable were my results.

III.

Analysis of Data:

On the developing paper, the sunblock which allowed the least amount of sun to penetrate, turned the whitest. When I observed the data from my first experiment I was very surprised at what I saw. I noticed that the SPF 30 sunblock was darker than the SPF 4 sunblock. This was very strange because I surely thought that 30 was better than 4. What I then saw was that in some places I had put more sunblock on the number 4 square than others, also the places where I had put more sunblock were the lightest and where I hadn't put much on it was the darkest. For trial one SPF 4 was the best, then SPF 8, then SPF 15, and last SPF 30.

For trial two, SPF 8 was the best, then SPF 4, then SPF 15, and last SPF 30.

For the second part of the project my results were not as strange, but were not what I expected. For trial one, "Bain de Soliel", which was the highest priced, worked the best. "Banana Boat", which was the least expensive, was second. "Bio Sun", the second highest priced was next, and then the second lowest priced, "Neutrogena" came in last.

IV.

Summary and Conclusion:

As I said before, I was very surprised when I saw the results of both tests. They did not agree with my hypothesis at all. For the first experiment, it seemed to me that it did not matter what SPF you used, but how much you put on of each one. That is why I think SPF is irrelevant, if you put a lot of sunblock on and keep reapplying it.

For my second experiment, I think it mattered how thick sunblock was. Bain de Soliel was the thickest and then Boat. But Neutrogena which came last was not thick and light. So, for my second experiment, I feel price does matter, but thickness does.

V.

the Banana was very not

Application:

I can apply the results of this experiment in many ways to my life now. I now know I can use any type of sunblock and the SPF will not matter. I will just have to remember to put a lot on and keep reapplying it. I also know that if I buy a sunblock and it has a thin texture to find another brand. These results can be critical for many people. With the depletion of our ozone layer, skin cancer is a common problem. People need to be aware of the SPF confusion and be informed about thick application of sunblock to prevent the damaging effects of the sun.