bobbyhiii,
You ask more questions than I can quickly answer. Often a conundrum for technicians that need to find a balance between learning and teaching.
But let me share a few thoughts..
The Portuguese 40 Reis, Nepalese 1 Piasa and Russian 1 Kopek were treated almost entirely with chemicals.
The others were very harshly dealt with physically. They are not acceptable in the commercial market. The Cuban coin has a serious dent so it will never have any value as a coin. And one would have to be a real Tyro to conclude that the Syrian coin had not been cleaned.
What, and why...
The what, is cleaning crud off of low value coins to expose their features and make them more pleasing to look at.
The why, is to learn about coins and coin “cleaning.”
By making a coin more pleasing to the eye, I can add one to my type collection, share one with the the check-out girl or spark interest in nusmismatics in my Nephew. For 10 cents.
And once you have done some coin “cleaning” you will know how to recognize cleaned coins. This may pay big dividends later.
Of those that were harshly dealt with physically, they are now in my type collection, when most people would have thrown them away.
And when I say physically dealt with, I mean the crud was scraped off after it was chemically softened.
I always start with a short bath in acetone. It will never hurt a coin and removes oils and contaminants that would not only damage the coin over time, but also impair the efficacy of other chemical treatments. I buy acetone by the gallon.
This old photo show my basic tools.
Notes:
The shot glass. When you fill it with acetone, and drop in the coin, the coin is only touched by the rim. Larger similarly shaped glassware is suitable for larger coins.
Chemicals. I use Coin Care, Verdi-Care, olive oil, Hoppe's #9, WD-40, E-Z-Est and MS-70. Every one is different, and each will produce different results. Experiment. On 10 cent coins. Observe and learn.
Scrapers. The most gentle is an artists brush. Used to brush away crud loosened by chemicals. Harsher is the tooth pick. When I use one, It must be sharpened (hence the pen knife,) and soaked in the chemical being used to clean the coin in order to soften the fibers.
Agate slabs. They are used to cover the glassware so as to inhibit the evaporation of expensive chemicals.
Now... If you can put a jeweler's loupe into the socket of your dominant eye, hold your coin by the rim and remove loose crud with a sharpened, softened toothpick, paint brush, Q-tip, or rose thorn, you are well on the road to understanding coin cleaning.
Aside from the fun and feeling of accomplishment you get when you salvage an ugly clump and transform it into a respectful artifact, you have also learned a process.
And when your dream coin is available at a price too good to pass up, you might be able to tell the seller, “I'm sorry but the color is off, it has been chemically treated, there are hairlines where common crud should be, and this is a cleaned coin.”
The last coin I purchased was $2600, and did so with confidence, because I know what I am doing and learned on 10 cent coins.
A smart man learns from his mistakes. A smarter man learns from someone else's.
