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Removing black spots from iron coin [solved]

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talking_cricket
Joined: 15-Oct-2015
Posts: 53
Hello everyone.
How can I remove the black spots from this coin without causing it any damage?



Thanks in advance,
Paulo.
glykan
Joined: 11-Sep-2013
Posts: 324
Looks like rust - if so, the surface of the coin is already irreparably  damaged. You can try to reduce the appearance of the corrosion using gun oil or WD-40 oil though I doubt that it will have a really significant effect.
Sorry for bad news...
talking_cricket
Joined: 15-Oct-2015
Posts: 53
Quote: "glykan"glykan
​Sorry for bad news...
​Even being bad news, it's something new i could learn.
Thank you for the help, tho. It's much appreciated.
Fluke
Joined: 22-Mar-2015
Posts: 1680
cant do much without altering the entire coins surface as it is rust (inert if it is black). Not something you can do without treating with the coin at extreme temperatures. It all comes down to how important the coin is to you and if it is worth doing.
Restoration addict : Verdigris Removal : Zinc White spot removal : Iron Rust Removal : Silver brooch/necklace mount Removal
talking_cricket
Joined: 15-Oct-2015
Posts: 53
Quote: "Fluke"​cant do much without altering the entire coins surface as it is rust (inert if it is black). Not something you can do without treating with the coin at extreme temperatures. It all comes down to how important the coin is to you and if it is worth doing.
​I bough it today and it was actually cheap, so even though i am happy for owning it, i don't feel attached to it like i feel with some other coins i own.
But, before doing anything I would like to know what could possibly happen to the coin by treating it at extreme temperatures.
Fluke
Joined: 22-Mar-2015
Posts: 1680
Worst case - You turn the entire coin black.
Best case - it neutralises the rust spots and the coin will turn slightly brown.

All coins react differently, even the same type/doubles can react differently. You wont find out without actually doing it. Sorry if that isn't much help.
Restoration addict : Verdigris Removal : Zinc White spot removal : Iron Rust Removal : Silver brooch/necklace mount Removal
talking_cricket
Joined: 15-Oct-2015
Posts: 53
No, it's ok.
You already gave me good information, Fluke, so, thanks.
As the rust is inert, i won't try anything yet, but will look for more info about the subject. When i feel confident enough i try.
One last question: a blowtorch do the job?
ArnoV
Joined: 23-Nov-2011
Posts: 575
For an iron coin of a hundred years old, it looks pretty good. Just leave it like that.

There is little gain in cleaning, and the risk of damaging it or making it less attractive is fairly high, particularly if you are no expert in the field.
 
Dato Mikeladze
Joined: 25-Mar-2014
Posts: 1827
Quote: "ArnoV"​For an iron coin of a hundred years old, it looks pretty good. Just leave it like that.

​There is little gain in cleaning, and the risk of damaging it or making it less attractive is fairly high, particularly if you are no expert in the field.
​ 
​Agree. Make  a photo after 10 years. - if spots  becoming large, you  will have to think what to do . And, I guess  cleaning technologies after 10 years will be much effective and   more professional.

yours
d
Numista referee for  Belgian Congo, Congo free state, East Africa, Egypt, Georgia, Katanga, Kenya, Libya, Ruanda-Burundi, Ruanda-Urundi, Seychelles, South Sudan, Sudan
Fluke
Joined: 22-Mar-2015
Posts: 1680
Yes, a blowtorch will work but you need to be careful with how you do it, too close/too long in flame and your coin will turn black extremely fast, getting rid of that is a nightmare.

I would leave it for now as those above have said, but if you still want to take a shot at it yourself, then keep it moving over the flame, not directly in it constant, even 2-3 seconds is enough to kill it.
Restoration addict : Verdigris Removal : Zinc White spot removal : Iron Rust Removal : Silver brooch/necklace mount Removal
Jesse11
Joined: 30-Dec-2015
Posts: 590
Quote: "ArnoV"​For an iron coin of a hundred years old, it looks pretty good. Just leave it like that.
​ 
​This is kind of how I feel about it as well. I like coins to show their age. Iron coins rust, zinc coins get white oxidation, silver coins tone (aka tarnish). If I find a naturally well-preserved coin, like a zinc coin that is smooth gray and unblemished, great, and that's probably the coin I would keep, but I don't mind seeing the natural aging process of a coin that has been around for a while and prefer not to try to "fix" it.
talking_cricket
Joined: 15-Oct-2015
Posts: 53
Yes, i will keep the coin like that.
Thank you all for the replies and the help.
MaRTWy
Joined: 16-Jan-2016
Posts: 1
You can try Phosphoric acid in 5-10% solution. It will react with rust and will leave Iron almost untouched, but solution should be not hot because when you see the bubbles then Iron is starting to react with Phosphoric acid.

FeO + H3Po4 = Fe3(Po4)2 + H2O - No Bubbles

2Fe + 2H3PO4 = 2FePO4 + 3H2 - Hydrogen Bubbles (very slow reaction in room temp)

It will remove shining from coin as well.

Other option is to use mineral oil (like from car engine) in ultrasonic cleaner for minimum 15 minutes - the longer the better :) 

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