Metal finishing Q&As since 1989

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Effects of Lime Away on copper

2006

Today my window cleaner used Lime-A-Way [affil links] on the window panes that were inside copper frames. The splatter from the spray caused pinkish discoloration of the copper. Is this permanent? Is there anyway to restore the copper which was darkening up due to oxidation?
Thank you!

Laura Jaget
homeowner - Las Vegas, Nevada, USA

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First of two simultaneous responses --

Hi Laura,
The chlorine in the Lime-Away is most likely the culprit. The oxidation can be removed by a few home brew remedies. Make a paste of equal parts distilled white vinegar [in bulk on eBay or Amazon], kosher salt, and white flour. Apply with small brush, leave on for five minutes, wipe dry. Rinse with mild soap and water. For mild oxidation, sprinkle kosher salt on a lemon wedge and rub until clean, rinse with water. I would treat one frame at a time so you don't get ahead of yourself. Good Luck!

Mark Baker
process engineer - Malone, New York
2006

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Second of two simultaneous responses -- 2006

What you are looking at is bare copper, exposed when the copper oxides were removed by the acid in the Lime Away (which is phosphoric). Were the frames a dark brown or were they greenish tinted? If they were greenish tinted, you can purchase a kit at some hobby stores that allows you to make what is called 'patina' on copper. This is actually a form of copper that has been oxidized. If the frames were a dark brown color, then I would suspect that they will darken relatively quickly again and you will not notice a difference.

The real question here is what kind of window cleaner uses Lime Away on a window? That is most definitely NOT supposed to be used on exterior surfaces where it can get to paint, etc. It seems to me that it was a shortcut instead of some good old fashioned elbow grease. I'd have them figure out the copper problem for you - on their dime. My suspicion is that it isn't the first time they have probably had an issue with this...

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania