How To Describe This Printing Error? Plate Flaw? Canal Zone #72 Odd Line

Is this a known error in Canal Zone 72? and what would you call it?
Thanks
Greg

The line inside the vignette would not be classified as an error. It looks like a plate scratch (a scratch on the printing plate). Plate scratches are typically straight lines while plate cracks tend to be more irregular. A quick look at French's work on plate varieties does not list this which may mean that it was a short lived scratch and may have been burnished out shortly after it was found.

My first instinct was that it is an un-erased Layout marker ( LOM ) but that should also be visible in the edges. It really seems too straight and too precisely vertical to be just a scratch but that is just my feeling

Peter

It's also exactly parallel with the edge of the design.

it appears to be a misplaced layout line. note the faint dot at the left, just about even with the acanthus scroll.

We called that a Doctor or Ductor Blade flaw in this previous discussion. They are a lot of fun to find.

https://goscf.com/t/51424

Partime -

That is the first thing that I thought of when I saw this stamp. Doctor blade. I used to fix high-speed printing systems back in the 70s and 80s. I saw this problem many times. A chunk of debris stuck in the doctor blade would cause lines. I would clean or replace the doctor blade to fix it. I was not printing sheets of stamps, but interesting that the same type problem occurred way back when this stamp was printed.

Linus

This is so interesting. I've never heard of this before. Cool. Dr Blade flaw it is.

The correct nomenclature is "ductor-" or "doctor blade", not "Dr blade"

Peter

thanks for the correction.

agree with the blade cause