The pick-up bars are the solid lines at the base of the sheets of stamps.
See here for an example.
https://www.earsathome.com/g6smrks.html
Edit. to add that they are also called Jubilee lines, although this term applied more to the multiple bars seen on QV and other reign stamps.
As an added extra and from another site,
"The purpose of the line was to enable the printer to assess the evenness of the plate wear. Sometimes, as in the case of the above block, the line is continuous. Other times, the lines were broken, with the breaks occurring in between the stamps."
So I guess that the term pick-up was probably a printers shorthand for seeing the plate wear more easily.
And there's more,
Having dug out my old book "Stamp Collecting by Stanley Phillips" he has this to say about Jubilee lines:-
"are intended to take the shock of the inking rollers, and raise them to the level of the printing surface of the plate. Without such a protection, the edges of the plate will have to do the lifting, and will wear away more quickly as a result"
So "pick-up" would be the term the printers would use, it picks up the inking roller.
Thank you all for the explanation. I had a suspicion it did relate to the bar under some stamps, which I do not have in my collection yet, but no mention in SG specialized.
SG Specialized catalogue mentions under Controls and Cylinder Numbers, with or without pick up bars. I am not clear on what a pick up bar is, can someone enlighten me?
re: GB King George VI
The pick-up bars are the solid lines at the base of the sheets of stamps.
See here for an example.
https://www.earsathome.com/g6smrks.html
Edit. to add that they are also called Jubilee lines, although this term applied more to the multiple bars seen on QV and other reign stamps.
re: GB King George VI
As an added extra and from another site,
"The purpose of the line was to enable the printer to assess the evenness of the plate wear. Sometimes, as in the case of the above block, the line is continuous. Other times, the lines were broken, with the breaks occurring in between the stamps."
So I guess that the term pick-up was probably a printers shorthand for seeing the plate wear more easily.
re: GB King George VI
And there's more,
Having dug out my old book "Stamp Collecting by Stanley Phillips" he has this to say about Jubilee lines:-
"are intended to take the shock of the inking rollers, and raise them to the level of the printing surface of the plate. Without such a protection, the edges of the plate will have to do the lifting, and will wear away more quickly as a result"
So "pick-up" would be the term the printers would use, it picks up the inking roller.
re: GB King George VI
Thank you all for the explanation. I had a suspicion it did relate to the bar under some stamps, which I do not have in my collection yet, but no mention in SG specialized.