Hungary Coins

How to clean old Austria-Hungary coins?
I have a lil collection of old coins. Mainly from Austria-Hungary era. Some of them are more than 200 years old. Any tips how to clean them?
You should not clean your coins. Most coin collectors see cleaning a coin as the equivalent of stripping down antique furniture and refinishing it.
When cleaning, the surface metal of the coin is often stripped. Anything used to scrub the coin will leave scratches (even 100% pure silk will leave hairline scratches). Most cleaning products will have some type of reaction with the coin’s metal and the surface metal can also be removed in this manner.
Your best bet is to leave the coins alone. Cleaning the coin will leave traces – which can be found by the knowledgeable collector – who in turn will not buy the cleaned coin. Also if you ever wanted to send your coin into a grading company, they can recognize signs of cleaning and will send your coin back in a “cleaned” slab (also called a “body bag” in the coin world) – which is usually a greatly decreased value.
If you absolutely must must must clean your coins do not use the method described above as it will react with the metal in your coin. Use 100% acetone (do not use fingernail polish remover!). It must be 100% pure because other additives will react with the coin metal. Place your coin(s) in the solution for several minutes (do not leave in for long periods of time). Rinse your coin(s) in distilled water. Next remove your coins and either pat dry with a soft cloth or allow the coin to air dry (air drying is better as you don’t risk scratching the coin with the cloth). NEVER scrub your coins!
I would still advise you to leave your coins as they are. They may not be bright and shiny but that is what most collectors prefer.
Super Mario Galaxy 2 [Episode 9]: Coin Chasers