| Author |
 Replies: 16 / Views: 7,268 |
|
New Member
Australia
8 Posts |
Copper 10 cent? I know you aint supposed to clean them but it was loose change which I found while detecting in the Vic goldfields. I cleaned it with electrolysis, when it turned out a copper colour I cleaned another 10c to make sure I hadnt copper plated the coin. The second coin came out silvery.  I have sent an email to the RAM but they must be too busy to reply.  Is this coin different or is it just some ground contamination? |
|
|
|
Pillar of the Community
Australia
1005 Posts |
I am not a expert, but it seems very unlikely that the coin has been struck on a blank the same size as a 10c but made of copper.
It seems to me to be much more likely that what has happened later on has changed the colour - particularly since you have mentioned electrolysis.
|
|
Valued Member
Australia
490 Posts |
don't hold your breath for the RAM to respond... I say PMD |
|
New Member
 Australia
8 Posts |
"particularly since you have mentioned electrolysis."
But the silvery coin in the pic was cleaned in the same way, same polarity, same amount of time, same solution.
|
|
Forum Mom
 United States
5877 Posts |
Since the coins came from change, you don't know what substances the coins had on them prior to being in your possession. That could affect how each coin reacts to the cleaning solution that you used.
You should weigh the two coins. I'll bet that they weigh the same. That way, you would know for sure that the planchets are the same material.
|
|
Bedrock of the Community
United States
10045 Posts |
 I think the weighing would rule out being struck on a foreign planchet. Since copper and CuNi are very similar in density (~8.9gr/cm^3, a 10c planchet punched from the wrong stock would weigh the same. |
|
New Member
Australia
8 Posts |
The coin weigh the same as a silvery 10c bit, it didnt come in my change I dug it up.
|
|
Pillar of the Community
Australia
1005 Posts |
"particularly since you have mentioned electrolysis."
But the silvery coin in the pic was cleaned in the same way, same polarity, same amount of time, same solution.
--
I said that because it sounds (very roughly) like a similar process to electroplating.
|
|
New Member
Australia
8 Posts |
"I said that because it sounds (very roughly) like a similar process to electroplating."
Thats why I did a second coin to eliminate the chance of me electroplating the coin.
I have cleaned numerous coins the same way including silver ones and this is the first that has turned out copper, apart from the copper coins of course, thats why I'm curious about this coin.
|
|
Valued Member
Australia
414 Posts |
I have seen this a couple of times. The main time I noticed it was after a heap of my parents coin were damaged by fire. The heat affected the coins appearance. The reason I'm not sure (staining, separation of the metal alloy, oxidisation from surrounding minerals etc etc). Did the area you found the coin detecting have fire/s?
Edited by b_j_w_79
09/15/2011 12:13 am
|
|
New Member
Australia
8 Posts |
Nope, no fires, the coin was basically just under the leaf litter.
|
|
Pillar of the Community
Australia
1005 Posts |
What does everyone think of this theory?
I have seen corrosion on modern silver (cupro nickle) coins which looks like the greeny blue corrosion copper forms.
Maybe the coin you cleaned was particularly green (after coming out of the ground) and the electrolysis purified the copper from the green corrosion?
|
|
New Member
Australia
8 Posts |
From memory it was more soil/dark coloured than anything, I didnt really take much notice as I was just going to clean it so I could spend it.
It didnt take long to clean maybe just a few minutes at 1 amp, the machine I use is rated at 20 volts, the amps change due to the coins conductivity.
Some of the old English copper coins I've found are well onto their way to turning back to copper carbonate(?) and they take ages to clean.
Edited by Brickie
09/15/2011 12:33 am
|
|
Valued Member
Australia
193 Posts |
I found a 5c in my garden and it was strongly copper coloured. I assume it must have been in the ground for years. I scrubbed it with a toothbrush but used no electrolysis to clean it. It also has a very matte surface which suggests some acidic action was part of the process it suffered in the soil. http://farm7.static.flickr.com/6088...9feb10_b.jpg |
|
New Member
Australia
8 Posts |
In all fairness to finding out why, I lit a small fire just now in my pizza oven, I placed a similar aged 10c in the fire the coin was sitting on coals that registered 850c, the coin was at 650c. I cleaned it the same way as previously. I also cleaned another 10c coin I had found in the bush at the same time today but with no fire. The fired 10c showed signs of coppering but soon rubbed off to a more silvery colour, the coin found in the bush and cleaned just remained silvery.  Original coppered coin left, fired coin centre, bush found coin with no firing. I know I'm a heathen but the final cleaning stage involves fine steel wool, I can just see you all cringing now...  the steel wool took off the coppering on the fired coin quick smart. Edited by Brickie
09/15/2011 01:22 am
|
|
Valued Member
Australia
85 Posts |
Take the coin to a dealer or several coin dealers and get their opinion mate
|
| |
Replies: 16 / Views: 7,268 |
Posted 09/14/2011 04:35 am
