Coin shaped seriously rusted

JeremyN · Feb 24, 2017

Hi,
I dug this coin shaped disc up out of the garden but it is very rusty.
The disc is magnetic and measures 50mm across. It has a black patina and is silver colored underneath

Any idea on how to get the rust off? I don't have a clue on the material of the disc so wasn't sure on what route to take in case I melt it or something.

I have a home made electrolysis setup and I gave it a quick dunk, got some bubbles but not much happened after that, bubbles just sat on disc. No visible cloud or anything. Used baking soda and a 9v charger in the tank.

So what do you all suggest?

I am in North East Germany on a property that pre dates 1873

flyin-lowe · Feb 24, 2017

If you want electrolysis to work you have to have good contact with the actual metal. You would need to scrape/sand/or grind a little spot where you connect to.

I can't tell from the picture but is there some type piece in the center of the first picture. Almost looks like the "loop" on an old button. Not sure. I am not a button guy so I am sure there is a name for the loop. :laughing:

OP3CRIMSIN · Feb 24, 2017

Only iron rusts like that so it's not going to be anything copper or silver. It will be pitted and probably worthless, but if you want any chance of removing the rust, you need an acid. Vinegar will work over time but if you want much quicker results, pick up some muriatic acid from hardware or swimming pool store and give it a dunk. Don't breathe it and do it outside in a plastic pail. I would only let it sit in there for five minutes on the first go around and then neutralize the acid by diluting it with water a LOT almost to the brim of the container, then follow up by adding baking soda slowly until it no longer fizzes. Then safe to dump on mother nature. Wire brush the item to get down into the pitted parts and if desired, dunk it again. Good luck.

MattLock · Feb 24, 2017

Wow no ones said that it's a elertcial box punch out yet that is what it is of course.

ScubaDetective · Feb 24, 2017

MattLock said:
Wow no ones said that it's a elertcial box punch out yet that is what it is of course.

Maybe. Are you crossing out the idea it could be a foreign coin? A lot of them are plated steel.

MattLock · Feb 24, 2017

How thin is it ?

JeremyN · Feb 25, 2017

It is 1 mm on the edge. The disc is slightly curved with a raised circle on the inside

I scraped a portion to get to the metal so will try again with the electrolysis. Will also try the vinegar bath as I have that to hand.

Will be interesting to see what is (if anything) underneath.

Many thanks for your replies, will post results as soon as I get anything.
Jeremy

sandgroper · Feb 27, 2017

I know that some of the older German coins were made of steel or had a steel core, we've got quite a lot of them in a box. I'm pretty sure the 1, 2 and possibly even the 5 euro cent coins are made of steel.

You might want to do some research into some older German coins that were made of iron and that have a 50mm diameter.

You could put it into an ultrasonic cleaner, they work great at cleaning things up, but looking at your coin, there might not be much detail left.

Good luck

Ricki7 · Feb 27, 2017

MattLock said:
Wow no ones said that it's a elertcial box punch out yet that is what it is of course.

That would be my guess , I was hoping he was able to clean it up . The slight curve is also consistent with elect knockout.
HH

JeremyN · Feb 27, 2017

Hi everyone, thanks for all the advice. Unfortunately once the rust came off it pretty much disintegrated. There was no detail left to suggest it was coinage, the raised centre was from a hole being punched from the other side.

In any event I learned a lot about cleaning finds from here and other research so hopefully this will stand me in good stead going forward.

I subsequently found a German DDR aluminium 1958 - 50 Phennig coin. My first real coin so I'm feeling pleased about that. It's not a Roman silver but I'll take it :-)

Coin shaped seriously rusted

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