$100 1990 FRN INSUFFICIENT INKING ERROR from IMPROPER BATTING SCARCE Ch XF

An impressive mistake on a scarce denomination that has a better story than first blush might suggest. When looking at this note, we immediately notice elements from the left end are absent, barely inked, and fully-embossed. Perhaps your mind immediately jumps to an insufficient inking error -- which as a seasoned error collector, you may have seen hundreds or even thousands at this point in your journey.

And if you're thinking it best fits into the Insufficient Inking category, you're not wrong, but as promised, there's more to this note than immediately meets the eye.

While the note is undeniably under-inked, this error occured as a result of improper batting making it far more impressive than a traditional insufficient inking error. The "batting" is a fabric covering that rests on the wooden boards underneath the currency stock. When the uncut sheets enter the press and undergo extreme pressure from the impression cylinders, the batting serves as an additional layer to help push the paper into the engraved recesses of the plate. When the batting underneath the paper deteriorates, compresses, or is improperly installed, some area(s) of the sheet is unable to receive the full pressure which leads to an incomplete transfer of ink from the engraved plate to the paper in that region. 

As shown on this example, the improper batting error affects the left portion of this attractive and problem-free error that's best suited for a collector with an appreciation for the unusual.