Coins struck from capped dies are not unknown, but they are extremely rare in the modern era. I saw one example on the mint director's desk at Denver in 1970 that was about six inches high composed of the remains of over 100 planchets deformed into an incredible mass of metal. Items such as that clearly don't leave the mint (legally) and eventually would be returned to the melting pot. Ancient brockage coins are one example where a planchet remains sitting on the die after striking and creates a negative impresion on the next planchet.

Knowing that it is extremely unlikely for a capped die strike to escape modern sorting techniques, I was intrigued by an example offered on Ebay of an aluminum token capped die strike, The lot included two pieces that dramatically illustrate the event:



The first image shows the twos pieces as they would have come off the press. The two pieces fit inside one another like a cup and saucer, although it is possible there were one or more intermediate pieces before these two were recovered from the press.

The next image is the obverse or top cup. It has the most dramatic lip, about a quarter of an inch deep. Note that the obverse image is sharp. It should be as it is in direct contact with the die. Basically, a normal token is struck, clear obverse and reverse images. The token has adhered to the top die for whatever reason (it could be the reverse depending on the design of the press--in general there has to be a direction for the metal to go. I am assuming the die comes down, the metal flows up forming the cup feature.). The reverse of the token forms a negative image on the planchet that comes in below it. The press is set for a set thickness, so the extra metal has to go somewhere, i.e. up forming the cup.



Notice the reverse is distorted. Without an original, undistorted example, I don't know how thick the token is supposed to be. Each piece is only one planchet as they weigh the same. When the token stuck to the upper die makes its impression on the new planchet, a reversed, incused image is formed and then the images distort as the metal flows outward to form the upper cup and lower saucer. The lower cup (or saucer) meshes with the upper cup, again the metal flowing up in response to the pressure produced by the descending die. Either the collar is not popping into place or the metal buildup is sufficient to impede its travel.



Notice the negative image inside the lower saucer is distorted as is the positive image on the reverse of the upper cup. The reverse of the cup shows an undistorted image of the token's reverse. It can only be so because the lower die is in normal contact with the lower planchet.

All in all, I thought this was a great example of a mint error that rarely escapes the mint and an interesting addition to my aluminum collection.

Edited 6/14/06 after more thought about how I described some of the process.

[attachmentid=1533]I was trying to find out what happened to this dime. Could this be a capped die? Sorry, I'm new to this, so any help would be appreciated. The back of this dime is normal.

I can't tell from the thumbnail and enlargements still are not working for me. I have to track down the post with the cut and paste cheat sheet.

I can't figure out how I viewed the attachments normal size and can't find the post that told me what to do. Is your dime saucer shaped, i.e. does the rim rise up irregularly around the head of the coin? Does it spread out irregularly (it would have had to spread beyond the collar and the collar could not have held two thicknesses of planchets)? The date and liberty would be misshapen from spreading outward. The bust seems to have an anomaly along the highest points of the center or that could be an artifact of the image, I can't tell from the thumb nail. If the coins is normal diameter without the cup shape it could be missing a clad layer, it could have been struck through something (a piece of cloth for example), or it could be damage received after leaving the mint.

Th first diagnostic in my mind is whether the diameter and shape of the coin are normal or exceeding normal in terms of having raised and spreading circumference.