Learning from an "Unfinished" Cast Counterfeit
Posted on 11/14/2007
Previously, I’ve written here about counterfeits made by casting. This time I’ll describe some casting process basics and some of the characteristics you might look for on a cast coin. Let’s look at a cast which shouldn’t fool any numismatist because it is so poorly made. Think of it as the “poster coin” for an unfinished project. Nevertheless, this coin shows parts of a cast that are rarely seen and which must be removed before the coin can be passed off as genuine.
Cast coins are made using some type of mold. A genuine coin is encased in the mold material to copy its design and then the mold is split apart after it dries. This creates a two piece mold with the obverse and reverse design and part of the coin’s edge being copied. When the two sections are joined to make the mold whole again (minus the genuine coin used as a model), there is a small seam left where they came together. Additionally, some holes called “casting gates” are needed in the mold so that the metal used to form the casting can be injected while air left inside the mold when it was joined together can escape.
Now that the faker has a mold, he is ready to make copies. In the “old” days, many cast counterfeits were made of soft alloys of tin and lead. That’s because these metals are easily worked and have a low melting point. A two-part mold made of brass or steel can be used over and over to make many copies without wearing out. As the need to make better-quality cast fakes arose, both the process and equipment needed became more costly.
Let’s examine the edge of a cast coin in the micrograph. Perhaps the first characteristic you’ll notice is the small “finger” of metal protruding from the edge. There is also a flat area near it and they are connected by two raised lines — one straight and one bumpy. The projection on the edge, called a “sprue,” is an artifact from a casting gate. It was formed by the metal left in one of the casting gates after it cooled. The two raised lines on the edge are formed by metal flowing into the seam where the mold was joined together. The raised lip of metal is called “flash.”
For some reason, the faker did not finish this item. Usually, the edge of a cast coin is filed flat in an attempt to remove all traces of the seam where the mold is joined. Hopefully, when you see what needs to be “fixed” on this fake, you will be more aware of some of the characteristics found on cast counterfeits.
This article previously featured in Numismatic News.