# Polishing copper, and the purity of the copper surface

**URL:** <https://boards.straightdope.com/t/polishing-copper-and-the-purity-of-the-copper-surface/839635>\
**Category:** Factual Questions\
**Created:** [September 3, 2019, 5:11pm UTC](https://boards.straightdope.com/t/polishing-copper-and-the-purity-of-the-copper-surface/839635 "2019-09-03T17:11:26Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\
**Post date:** [September 6, 2019, 7:04pm UTC](https://boards.straightdope.com/t/polishing-copper-and-the-purity-of-the-copper-surface/839635/21 "2019-09-06T19:04:35Z")

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You could go back to the shop that originally polished it and ask them to set you up with some sort of daily/weekly protocol for maintaining it.

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**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\
**Post date:** [September 7, 2019, 12:16pm UTC](https://boards.straightdope.com/t/polishing-copper-and-the-purity-of-the-copper-surface/839635/22 "2019-09-07T12:16:58Z")

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> [@Napier](#):
>
> Do you know how fine a ready-made abrasive paper is available, and how glossy it would make copper?

One widely sold brand with a good reputation is 3M Imperial Wetordry, which is available in a full range of grits up to 2000. (Despite the name, grits above about 400 should always be used with water - they clog rapidly when used dry.)

2000-grit used on plexiglas yields a finish that, optically, is almost as good as glass. I doubt you’d need anything better for copper, and even 1000-grit is probably sufficient. The first time you polish the surface, you’d need to start fairly coarse and work steadily up through the grits.

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**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\
**Post date:** [September 7, 2019, 7:39pm UTC](https://boards.straightdope.com/t/polishing-copper-and-the-purity-of-the-copper-surface/839635/23 "2019-09-07T19:39:56Z")

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Is it wrong to assume you are working for or in conjunction with a major university? If not, check to see if they have a Materials Engineering department. Those guys routinely polish metal samples to be both flat and free from visible scratches (this is necessary for microscopic examination, an Optical Microscope has a very shallow depth of focus at 500X and scratches disturb the metal which compromise the examination). If you don’t work for a university with a Materials Engineering dept, there is likely one close to you that could help.,

As for maintaining the surface, they may also be able to suggest a solution. I would think that a electroplating of gold would do. The thermal conductivity of gold is close to that of copper, and with a thin coating, I doubt it would make any difference.

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