Science Buddies: "Ask an Expert"

Hello,

My 5th grader will be testing effectiveness of handwashing vs hand sanitizer for her science fair project. I've ordered glo germ but am unsure how to test the amount of glo germ left on hands after cleansing. She will document what she sees but how does she quantify the amount left?

Thanks,
Karen

Hello,

I actually just used GermGlo today for a local science-outreach project that was looking at the same aspect - hand sanitizer vs washing hands. Something important to remember is to keep the type of hand washing constant (ie. between fingers, back of hand, length of time, etc.).

As far as quantifying, the germglo actually feels like regular hand lotion with speckles in it that glow under the black light, so quantifying will be a little difficult without a fluorescent signal detector. When we used it today, the glo mostly only stayed within the crevasses of the palm. You could use a ruler and measure the length of the hand creases affected vs unaffected. Some other idea is that you could look at the hand and measure in segments of square centimeters. Count the number of square centimeters with any visible glow vs completely empty squares. Another quantitative option could be testing the ability of the glo to be transferred from hand to hand. So you could have your child shake hands with someone, and then have that person shake hands with another person and so on and so fourth and see how many hands the glo can be transferred to.

Hope this helps.

Thank you so much for your response! We decided to measure our results using square inch centimeters of the hands. I do have another question for you, since you did a similar project. We are using 2 types of hand sanitizer (alcohol-based vs. alcohol free) for our independent variable. What I've found so far is that the hand sanitizer does not remove any of the glo germ. So I'm wondering if glo germ is ok to use with hand sanitizer?

We have found that it does work okay- as long as you rub your hands together similar to how you would if you were washing your hands with some. I'm not sure how accurate the germ-glo is in determining the effectiveness of hand sanitizer, though. By that I mean I'm not sure how good of an indicator it is.

What you could do is rinse you hands with water after using the sanitizer. So you would be able to compare washing hands with A. soap B. no soap and C. sanitizer. Normally people wouldn't use sanitizer and then run their hands under the faucet, but the water might be needed to wash off the germ glo.