Metal finishing Q&As since 1989

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citric acid in cleaning metals

I am Nas. I'm a high school student in Singapore and I am doing a school science project requiring experimental investigation. I work with lime juice, lemon juice, orange juice and grapefruit juice, which all have citric acid . I need to know the amount of citric acid in each fruit juice because I am comparing if a piece of copper strip will be shinier if I clean it with different fruit juices. How exactly does the citric acid play a part in this cleaning process? Thank you for reading my letter and I hope I can get a reply soon because I am meeting a deadline.

Nas W [last name deleted for privacy by Editor]
school - Singapore
2004

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April 5, 2008

Hi, Nas. We have an FAQ about cleaning pennies which should be quite relevant. The thing is, though, how will you be able to establish that the citric acid is the material that is responsible for shining the metal?

This approach, of knowing the citric acid content before you do the experiment, can lead you towards "junk science", i.e., knowing the result you wish to get, then talking yourself into discounting contrary observations and giving far too much weight to supporting observations.

Much better to carefully conduct the experiment first. Document your actual results, and then try to find a cause or explanation for the results. Good luck.

Regards,

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