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Techniques for CollectorsCleaning Copper xls?

24th May 2007 11:13 UTCJon Ertman

What is the best way of Cleaning Copper xls?Tarnix?

24th May 2007 14:17 UTCPeter Haas

http://www.mindat.org/mesg-19-65376.html

On native copper, ammonium salts (best choice would be ammonium acetate) and citric acid solutions do the same job. Citric acid works faster, but attacks many secondary minerals, so take care. For instance, malachite will survive ammonium salt solutions, but not citric acid. Do not heat the solutions (for obious reasons ...).

24th May 2007 16:21 UTCJolyon Ralph Founder

Of course, it has to be said that if you have an old and important copper specimen it's not a good idea to clean it as it will devalue it.

Jolyon

24th May 2007 17:41 UTCAnonymous User

Well, it depends on how big the xls are. However, I´ve made good experiences with tooth brush paste! This works also for old doorhadles made of brass. But I´m gettin´ off-topic anyway...

Andreas

24th May 2007 18:10 UTCJoseph Polityka Expert

I remember this method from my childhood for cleaning a tarnished penny: cover the item with white vinegar, then pour about a teaspoon of table salt into the vinegar. The penny shines almost immediately.

To paraphrase Jolyon you do not want to clean a copper specimen with any aesthetic or antique value.

Let me know if the penny method works.

27th May 2007 13:09 UTCjon ertman

I tried the vinegar,works goood on pennies,it may not work on native copper,so well. After a day it tarnished badly,put in my ultrasonic it removed some it.

28th May 2007 02:33 UTCDavid K. Joyce Expert

Vinegar works to some extent. Very slow, however.

I have found, BY FAR, the best reagent for cleaning copper is sulfamic acid. I learned of this acid from people in the Upper Penisula of Michigan during collecting trips there.

Sulfamic acid cleans off copper tarnish and corrosion but does not seem to dissolve the copper itself. I purchased a 50 pound bag with two other fellows, split it three ways and have been using that third-bag, for years, to gently clean copper specimens. You don't need much. I just immerse the specimen in hot/warm water with some sulfamic acid dissolved in it and remove it when the specimen is cleaned to the desired extent. ALWAYS outside where ventilation is excellent. I NEVER use any acid except vinegar inside.

David K. Joyce

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