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What type of vinegar cleans a penny better?


Q. Hi! My name is Marvin. I'm doing a science fair project about which kind of vinegar [in bulk on eBay or Amazon] cleans a penny the fastest. One of the requirements is to interview an expert & since you are the expert I'd like to interview you. Before I ask you a question, I would like you to know that I would be using: white vinegar, red wine vinegar, white wine vinegar, rice vinegar, & malt vinegar (all added with 1 tsp of salt).

1. What is your name?

2. What is your field of expertise?

3. Have you done this experiment before?

4. Which vinegar cleans a penny the best?

5. What chemical in this vinegar cleaned the penny better?

6. Did the acidity of the vinegar made the difference?

Please respond ASAP as this is requirement for my experiment in science. Thank you very much for your time and your technical expertise. Andrsen Air Force BAse DODEA Guam Middle School.

- Dededo, Guam, USA

A. Please tell your teacher as politely and respectfully as possible that your "expert" suggests that you do the project in the opposite order, Marvin :-)

You should DO THE EXPERIMENT FIRST, AND ONLY THEN compare your results with what the "experts" have to say. To ask for the result before you do the experiment will teach you to rely on hearsay instead of experimental result, and to unconsciously jury-rig the experiment to achieve the result you were told to expect. This is the opposite of the "scientific method" -- it is what we call "junk science" -- a major plague today. It tempts you to ignore your own results, alter the procedure, ignore any wackiness in what you're doing, and just keep at it until it gets you the results you were looking for. For your research please consider this one-minute historical lesson from Richard Feynmann (dec.), one of the world's most highly respected physicists and best teachers ...


1) My name is Ted Mooney; 2) my field of expertise is metal finishing; 3) I have done parts of the experiment before (I have cleaned pennies with salt and vinegar several times) but I have never compared different types of vinegar; 4) I don't know; 5) acetic acid is the ingredient in vinegar that contributes the most to removing tarnish from pennies; 6) the acidity is what does the job, so I would expect the vinegar with the most acid to work the fastest.

My guess is that you will see no measurable difference in performance between any of these vinegars. But that brings us back to the beginning again, because I have now corrupted you into believing the experiment will show no differences before you've even started it. So as soon as you get some differences you will be tempted to discount them and write them off as experimental error ... and we will have educated yet another student into a lifetime of junk science :-(
So please do the experiment first! Keep a notebook (lab book) with numbered pages, write down everything you do and observe in ink, (you never erase anything you've written, no matter how wrong you think it is. Strike it thru but leave it legible). A proper lab notebook should get you an A+ on the project irrespective of your findings. Good luck.

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Ed. note: Students, please search the site for similar threads or read our F.A.Q. on the subject. Good luck.

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