Earl,
As other have said toothpicks are usually safe but nothing is guaranteed. I have many of those coins Ariech wrote about with the soft green
patina which can be damaged even by rubbing your finger on it.
If it helps here is how I think of it:
The stuff that has adhered to the surface of the coin - dirt, dust, sand, concretized encrustations, - has a certain hardness. This will vary for each coin but you can quickly learn the general groups.
The
patina on the surface of the coin itself has its own hardness. Many patinas are quite hard and firm but they range down to some that are not much more than a layer of soft
fine powder.
Each tool has its own harndness. In generally ascending
scale - skin, soft toothbrush, fingernail, hard toothbrush, silver brush, soft
brass brush, toothpick, plastic (actually plastics vary - some softer than this and some harder), bamboo skewers, not-so-soft
brass brush, brass
pick, x-acto knife, steel
pick, steel scalpel. [Some readers my quibble with the exact order but it gives you a rough idea].
Of course you have to factor in pressure and technique. You can clean many patinas with a hard steel scalpel if you are careful and you can even damage a hard
patina with a softer brass
pick if you push too hard.
Ideally you need a tool that is harder than the stuff adhering to the coin but softer than the actual
patina on the surface.
If your coin fits into this category you are usually in a
good space. You just start with soft tool and
work your way up the hardness
scale (obviously with experience you will get to know right away what to start with). You end up with a tool that is removing the dirt and not harming the
patina.
Sadly, most cases don't
work like this. Instead the hardness required to remove the dirt and stuff is such that it could harm the
patina too. Either the dirt is very hard or the
patina is more susceptible.
So you either try to soften the dirt and stuff such as via soaks in distilled water or you use hard
tools with certain techniques. So one person will look at a coin and decide they will keep soaking it and only use toothpicks and just wait until the dirt gets soft enough for the toothpicks to
work. Another person might instead take steel scalpel and
pick and
work under magnification to
pick and shave away the hard dirt. The first person risks waiting a long time and maybe never having the dirt soften. The second person risks harming the
patina if they slip up.
The
choice is personal. But as G Jon says you can use your not-so-nice coins for learning. Try some of the more aggressive techniques on coins that are otherwise hopeless.
Search for threads about pin-vises and scalepls or x-acto knifes to learn about them. You can then stick with the milder methods on any coins that show potential and move up as you get more comfortable.
Shawn
Oh, yah, and as Areich noted some coins are just hopeless. Sadly the less reputable dealers knowingly pass these coins on in the cheaper lots.
