The simplest way to measure the thickness of something functionally flat, such as a coin, is to stack them up and divide the thickness of the stack by the number of coils in the pile. Even very old coins minted in the United States have a border. You may find that very old coins actually thicken over time because of corrosion and grime.
Coins in the United States contain no silver. In the current minting process,
- Pennies are copper plated zinc and 1.52 mm thick
- Nickels are just 25% nickel with a balance of copper and 1.95 mm thick
- Dimes are 8.33% nickel and the remainder is copper at 1.35 mm thick
- Quarters are the same composition as dimes and 1.75 mm thick
- Half dollars are also 8.33% nickel and are 2.15 mm thick
It’s interesting to note that the three primary coins that have a reeded or rough edge have only 8.33 percent nickel. Coins are stamped in presses that strike the metal with tons of force.
The edges are either smoothed or treated with the reed pattern in this single strike. Commemorative coins with writing on the edge of the coin have to go through two pressings.
Can Coins Wear Out?
The value of a coin is not altered by physical damage. For example, if you drop a penny in a garbage disposal, it may get banged around, but it will still be work $.01.
Interestingly, because coins ae pressed rather than forged or poured, damage may cause them to actually be thicker; a ding on the surface of the coin will create a bubble elsewhere.
If you’re stacking old coins to get a thickness measurement and the stack wobbles or you can see gaps, one of the coins is either damaged or dirty.
The critical concern when considering whether the value of the coin is lowered by thickness loss is related to weight. While a very old penny may who muted features of Lincoln and feature some cherry tones in the copper color, it will not lose weight. Worn, corroded and dirty coins do not lose any value.
Tools for Collectors
If you’re planning on building a coin collection, consider investing in a set of calipers that will allow you to measure the thickness of an individual coin. In addition to measuring, you will want to be able to carefully clean, dry and eventually store your coin. Digital calipers will be much easier to read than the gauges.
For those checking out a new coin, it’s a good idea to measure and multiple points around the circumference of the coin with your calipers.
Cleaning Up a Gunky Coin
If you notice variation in your measurements, discoloration on the surface or a sticky, tacky feel on the surface of the coin, clean the coins in warm water. If you still see discoloration, use a bit of dish soap to clean away more dirt.
Our fingers can transer oil to the surface of a coin, which means it will pick up more dirt each time it gets used. Use a soft bristle brush, such as a stipple brush, to gently brush off the coins as you wash. Finally, dry the coins with a lint-free cotton towel.
The towel may well become discolored over time. This is not a task for an heirloom set of tea towels; you want basic cotton fabric that will absorb moisture without leaving any lint on the coin.
Pat, rather than rub, the coin to avoid snagging any dings in the surface that you can’t see with the naked eye. Remeasure to look for any metal loss across the face of your coin.
You will also need airtight containers to keep your coins from oxidizing any further. Finally, make sure you put your coins on a flat surface where they won’t get knocked to the floor.
Some Simple “Never” Activities for Collectors
Never use an acid to clean a coin, such as vinegar if you don’t know the age. To that end, never use bleach. Do look for hard plastic airtight containers with no paper inside the box to keep your coins from more damage.
The sulfur used to make paper can lead to acid damage on the surface of your coin. Even copper can blacken with long term exposure to paper.
When to Hire a Professional
If you’re getting serious enough about coin collection to get a set of calipers and the airtight containers, it’s time to reach out to other collectors so you can make connections with professionals who can help you clean very rare coins.
If a coin is dirty enough that you can’t tell what’s on either side of the coin, try warm water alone. Don’t brush or scrub a coin of uncertain age; you can damage the surface and destroy the value.
Even if you’re not keen on old coins, collecting coins from around the world can be a great deal of fun. Do make sure you list the name of the coins under the in your collection display; you don’t want to have to handle it and get more oil on the surface to remember the source and value.