What Went Wrong -error coins that escaped the Mint
Figure 1 – Australian 1956 florin with ragged clipped planchet error
Clipped planchets are one of the most common errors seen by collectors. Despite this, they can be one of the hardest to understand error types. Frequently we see the new collector crying out “I could just make that with some tin snips!”. Of course, this is often wildly inaccurate. All a collector needs to pick a real clipped planchet error from post mint damage (PMD) is a basic understanding of the coin manufacturing process and the ability to visualise how metal might flow when a coin is struck.
Shown in Figure 1 is a 1956 florin with a good sized ragged or end-of-bar clipped planchet error that weighs just 10.86 grams. When posted on our social media channels this coin generated some heated discussion, with one commenter suggesting it had been “freshly broken” and “clearly hit with a hammer”. Did we indeed post up a broken coin that we’d hit with a hammer? Of course not. Let’s examine the coin in detail and explain why this is a genuine error.
Blakesley Effect
The new error coin collector must understand that many coin blanks are pre-rimmed by an upsetting mill BEFORE they are struck. The upsetting mill (not surprisingly) upsets (raises) the rim of the coin blank. This helps to reduce the striking pressure required to make the coin and to ensure a high, protective rim that helps to preserve the coin design as it circulates. A raised rim is created by running the coin blank under pressure between two metal rollers. However, when the blank is incomplete (as was the case here) no force can be applied opposite the missing area of the coin and strike weakness will be evident. This effect is known as the “Blakesley Effect”, named after the numismatist who first identified it. Figure 2 clearly shows the area of weakness on the rim opposite the missing region of the coin.
Figure 2 – Blakesley Effect
Metal Flow / Fishtailing in Legends
When a coin blank is struck under extreme pressure it essentially behaves as a semi-plastic fluid and will flow along the path of least resistance. This is how the metal of the coin blank “fills” the coin die when it is struck. In the case of a clipped blank the path of least resistance is TOWARDS the missing area of the coin. Metal will flow OUTWARD in the lettering of the dies filling the outside end of the letters. This leaves the inside end partially filled often with a typical “fishtail” type shape. Which gives rise to the name “fishtailing” of the lettering. Figure 3 shows weakness and fishtailing at the base of the letters and numerals “H II D” on the obverse.
Figure 3 – Fishtailing
Gradual Metal Transitions
It seems intuitive that breaking or cutting a coin will result in metal deformation and sharp transitions near the edge of the cut. When a clipped coin blank is struck this is not the case. Transitions from the completely struck up area of the coin to the missing area of the coin are gentle as the strength of strike weakens gradually because there is not enough metal to fill the die. This will be most obvious on the rims around the missing region of the coin and will also be apparent in any rim beads or rim denticles. Figure 4 shows obvious weakness in the reverse rim denticles near the clipped region of the coin.
Figure 4 – Weakness in Denticles
Conclusions
Once the time is taken to understand how a coin is made and how coin metal flows when struck it becomes a reasonably simple task to separate the wheat (genuine clipped planchets) from the chaff (the damaged coins). In fact, often it is possible to pick a genuine error from post mint damage from relatively poor online images once you know what to look out for. If, in your collecting journey you see someone post up a coin with a piece missing make sure you evaluate it carefully before commenting “I could create that with tin snips!”.
Mark Nemtsas and Kathryn Harris own and run ‘The Purple Penny’ coin shop in Adelaide and are passionate about error coins.
