Error Is Human: Part II

Part II of a two-part series discussing the US errors that PMG will recognize, grade and encapsulate.

Just in case you missed Part I of my article, you can find it here. The Bureau of Engraving and Printing (BEP) does make mistakes, although not that often. But when they do, occasionally the errors they produce have a jaw-dropping appeal to them. To repeat some basic information:

There are three basic stages of the printing process. Errors can and do occur at any of the three stages listed below:

  1. First Print—Is the back of the note.
  2. Second Print—Is the front of the note that includes the portrait and border.
  3. Overprint—This may include both treasury and district seal and the serial numbers.

This article will display nine different errors that PMG certifies, some of which are uncommon, while others are much easier to find. These two articles combine to show 19 examples which cover approximately seventy percent of the US errors PMG certifies.

Overprint on Back Error:

Overprint on Back Error

As the name suggests, this error occurs with the overprint (serial number, treasury seal and if applicable district seal). This happens when the uncut sheet is fed upside down into the press. This error occurs roughly equally across all small size denominations except for the $2 (with about 12 known from the 1976 series to present).

Mismatched Serial Number Error:

Mismatched Serial Number Error

A mismatch occurs by one of two ways 1) manual error 2) mechanical error. A manual error occurs when the operator doesn’t set the same number sequence on both of the numbering wheels prior to the printing process. This usually results in the serial numbers discrepancy at the beginning of the serial number while those numbers at the end are identical (example: A12xxxxxx / A13xxxxxx). The mechanical errors happen when one numbering machine gets stuck on a number while the other continues to advance properly. This type of error effects the end of the serial number while the beginning stays constant (example: Axxxxxx76 / Axxxxxx77). Other types of similar errors are: mismatched suffix or prefix errors, and the least common mismatched national bank charter numbers.



PCBLIC Error Close Up

This error is only on the 1907 $5 Legal Tender, more commonly known as the “Wood Chopper”. This is an engraving error and can be found on the back right of the note (see the above picture). Instead of “PUBLIC” the word “PCBLIC” is seen.

Wet Ink Transfer Error:

Wet Ink Transfer Error

Wet Ink Transfer is where ink from one note is transferred to another during the drying process.

Paper Jam Error:

Paper Jam Error

The Paper Jam Error is usually a combination of a printed fold error and a tear.

Inverted Back Error:

Inverted Back Error

This error is where the back of the note looks to be upside down compared to the front. It happens only by human error—the backs are printed first, and then the uncut sheets are rotated 180 degrees and then printed. The truth is that the fronts (or second print) are actually the side that is inverted, but because one would normally view the front first and then the back second (thus making the back look upside down) the term “Inverted Back Error” was born.

When dealing with small size, this error is broken down into two types (Type I and Type II). There is a very easy way to distinguish between a Type I and a Type II: any series before 1981-A is a Type I and any note with this error beginning with 1981-A is a Type II. The look of these two errors is also different. Type I has a well centered front and back, while Type II appears to have a large misalignment of the back. This was caused by a change in the cutting stage.

Inverted Overprint Error:

Inverted Overprint Error

This error occurs in the same way as the error above except that the uncut sheet was rotated 180 degrees before the final overprinting process.

Test Note Error:

Test Note Error

Before the printing process begins, the plates are flooded with ink to test the press. These notes are supposed to be destroyed after the test is concluded.

Double Denomination Error:

Double Denomination Error, front

Double Denomination Error, back

This is the King of all errors. The type of error every collector wants in their collection. The double denomination error occurs only when the backs of one denomination are mistakenly mixed with the fronts of another.

In summary, the obstructed printing error (read about this error in Part I) and the double denomination error are the two most sought after (and expensive) errors that can be found. That doesn’t mean that the other errors are not as exciting. Each error has a story to tell, and each error is like a puzzle—how did it happen and when in the printing process did it happen? Happy hunting.

Note images from

PMG is an independent member of the Certified Collectibles Group (CCG).

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