Best Way To Clean Copper From Solid Black Tar

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Author	Replies: 4 / Views: 1,766
Nic Pillar of the Community Philippines 1156 Posts	Posted 09/22/2009 04:43 am I have accumulated more than a handful of copper coins that have turned completely black with micro-solid encrusted tar and/or black stained and completely unreadable. Now interested to find out just what these coins are, What would be the best solvent to clean copper? Please note, have tried toothbrush with detergent powder, toothpaste, bar soap, Q-tip with acetone, but the black stain (Tar?) just wont go away. Any suggestions? Thanks! Report this Post to the Staff

vermontensium Moderator United States 16677 Posts	Posted 09/22/2009 04:56 am Sulphuric Acid Seriously, whatever you use, be very careful swcoin.ecrater.com Report this Post to the Staff
RFB Pillar of the Community United States 532 Posts	Posted 09/22/2009 05:50 am If you have already scrubbed them and used harsh chem you cant actually hurt them at this point. You own a rock tumbler? Report this Post to the Staff
Sap Moderator Australia 16810 Posts	Posted 09/22/2009 08:19 am If acetone did absolutely nothing to it, then it's not "tar" - if it's black and your treatments aren't doing anything, it's most likely fire damage or something else environmental that's caused actual corrosion. Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis Report this Post to the Staff
Nic Pillar of the Community Philippines 1156 Posts	Posted 09/22/2009 6:32 pm Thanks all and noted too! the coins are just about useless because they are still year-date unreadable. But useful for "experimentation". Lacking any other option, will try sulphuric acid drops on one stubborn piece, not to clean but to see if this black stain will dissolve...may be even fun... like hi-school chem lab! Thanks RFB- no rock tumbler yet Report this Post to the Staff
	Replies: 4 / Views: 1,766

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