testing sunscreen effectiveness

[cjewell1267]

I am helping my daughter with the above mentioned project. Unfortunately, we are now down to the wire with actually working on the experiment portion and find the Oregon Scientific personal UV monitor is not working properly. I spent 45 minutes on the phone last week with one of their technical people the beginning of last week and we still weren't able to get the device to work properly. What can we do at this point? Her project is due this week!! YIKES!!
Thanks,
Carol
P.S. I also found that The Wall Street Journal did a piece on this device and they had the same trouble (device indicates you can stay out in the sun for almost 40 hours - which we both know cannot be right).

[donnahardy2]

Hi Carol,

I can offer sympathy on the failure of the sunscreen monitor and the lack of results for the science project. I have had the same experience a few times working with kids, due to someone kicking over the bucket containing the project, the lack of static electricity in humid weather, and a number of other reasons. However, all is not lost. Your daughter can write up this project and enter it with no results. Science projects are usually scored on a point count, and your daughter can get all of the points that can be awarded for the question, hypothesis, materials, methods, discussion, conclusion, reference sections, and the attractiveness of the display. In my experience, this can qualify for an "A" and up to a second place ribbon. It's the process of doing and reporting the project that's important, the results are nice, but not absolutely required.

I recommend reviewing the handout from the teacher that lists everything that must be included in the project. Be sure to explain the science behind the project, and include references. The Wall Street Journal reference about the failure of this piece of equipment should definitely be included. In place of the results, your daughter can report that there are no results and she can describe the details of what went wrong, and what she tried to do to solve the technical issues. Some humor will help. In the discussion/conclusion section, she should explain how she would do the project if she had time to start over again.

I hope this helps.

Donna Hardy

[deleted-71417]

Hi,

I have no experience with the Oregon Scientific instrumentt, but I can offer some leads to solving your problem.. First , click on the top left tab on this page( Science fair project home), then enter sunscreen effectiveeness in the search box at top right, and search. If you read through the search results you will find a number of ways of doing this experiment.

Second, even though you do not believe the absolute numbers your meter is producing, if the meter results change with different sunscreen samples reproducibly, it may be working well enough to usee, as long as you view the readings as relative, rather than absolut.. Just try to do the experiment and then compare re;ative numbers, and see if they make sense..

One reason it might have read 40 hours is because the particular sample you used almost completely blocked the UVA and UVB rays. We both understand that on real skin the lotion would wear off or be washed off or absorbed away from the skin in less time, but the reading could be accurate if those processes did not occur. So I would not give up out of frustration yet.

Play around and see if you can get some sensible answers from the ex[eriment.

Trooubleshooting remotely is an inexact process at best, so unfortunately you are own and I cannot provide exact answers under the best of circumstances.

Godd luck and have fun with this!

Best regards,


Barrettt L. Tomlinson

[cjewell1267]

Thank you all for your replies. The device definitely isn't working properly because I tried changing the information, using 2 different SPF lotions and nothing at all, and still came up with the same results each time. I think we are either going to try a different perspective or just write this portion of the project off.

Thanks again,
Carol

[donnahardy2]

Hi Carol,

Barrett gave you excellent advice on trying to salvage this project. Obviously, getting some results, even if they are relative and not absolute, would be better than no results.

What is the reading on the meter when you use no lotion? Does it ever go to zero?

Donna Hardy

[deleted-26690]

We successfully got some decent readings with the monitor. We got a 3 as the control reading, plastic wrap without any sunscreen, and then when we used SPF 50 and SPF 85 the monitor read 0.

The experiment says to subtract the blank plastic reading from the plastic and sun lotion reading and the result will show how much the sun lotion reduced the UV radiation. Obviously our answer with both sunscreen levels used is -3 but what are we actually measuring? The teacher does not understand what we are measuring, and I am a little confused as well. Can you clarify what -3 is in this case?

[MelissaB]

Hi! After looking on the web, I -think- that your monitor gives you the UV index. Wikipedia has a great article on how you can interpret those numbers, here: http://en.wikipedia.org/wiki/Uv_index .

Ideally, I think you would do the test on a day with a higher UV index. It is entirely possible that the sunscreen actually protects better, but that you were not able to measure it because the UV radiation was not that high that day. Of course, you may not be able to/want to do the experiment again, in which case it's fine to just discuss this in your conclusions.