DANG_BLUE

Help me, please...
I've done the most stupid thing: I put my coins into acid (HCL and H2SO4) so my coins look very bad: dirty. How can i remove it?

(Sorry for my bad English)

National dealer

What coins did you dip in acid?

DANG_BLUE

All of my coins. Some of them are: Gold color and Silver color like: 5 Rupees India, 25 centavos Nicaragua, 20 and 50 of Australia, 5 dollars Hong Kong, 1 cent of America, 1 Plastre Indochinoise, ...

Ben_Bovas

I'm sorry. What you have done to your coins is most likely irreversible. Acids, such as hydrochloric and sulphuric, will etch (dissolve) the surfaces of all but the most inert metals, such as highly pure gold and platinum. How quickly this happens depends on the strength of the acid, which may be indicated on the label of the acid container, if it is a commercial product.

Once the surface is etched, nothing can be done to restore the original appearance. The surface has been altered. Metal has been removed and cannot be replaced. To prevent further damage the coins should be rinsed thoroughly in clean or distilled water. If you like, to neutralize any acid remaining in microscopic pores (a result of the etching,) you can rinse the coins in a solution of baking soda dissolved in clean or distilled water. Following the baking soda bath the coins should be rinsed in clean or distilled water.

DON'T USE ACIDS to clean your coins if you value them for standard numismatic reasons.

You can learn from this mis-adventure. If you want to see the results of the etching I suggest that you find a microscope somewhere (a school, college, local consulting scientist, doctor or pharmacist.) Under appropriate magnification and lighting a different kind of beauty may be revealed to you. You may be able to see the previously unseeable crystal structures of the coin surface. Metallurgists and engineers regularly use acid etching to see the underlying crystal structure of polished metal samples.

DANG_BLUE

Thank you very much for your answer. But what is "baking soda"?
Some of my coins become red color, how can i turn it into white color? I know I can't recover the surface, but how about the color?

GDJMSP

Baking soda is a common household item sold in any grocery store. It has the effect of neutralizing acidic chemicals.

But I am afraid Ben_Bovas is correct - what has been done cannot be undone. The best thing you can get from this experience is what you have learned about using acid on coins. Don't do it.

As a general rule cleaning or conserving coins in any manner is not a good idea. Especially when undertaken by the inexperienced and many times even by the very experienced. It is all too easy to ruin a coin and destroy any numismatic value it may have.

I would suggest that you read this article about the proper handling of coins - Proper Handling

There are a great many other informative articles available on the Coin World site - read them. Just type a key word into the Search box and hit the Enter key on your keyboard.

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DANG_BLUE

Ok, thank you very much!