How Did Engravers At Babn In 1980 Make Changes To An Engraved Cylinder?

Working on a project and in need of expert help. In 1979 to 1981 small vending booklets were printed by BABN in Canada. There seems to be a series of changes made to the engraving cylinder. There were 72 booklet panes on the cylinder and the cutting guide on the tab (selvedge/selvage) was originally made of horizontal lines then changed to diagonal lines then changed again to horizontal lines. The rest of the cylinder was untouched. The flaws on the rest of that cylinder did not change so it was not a wholesale change. Any thoughts from those in the know?

Because the micro-flaws on the remaining 72-subject panes remained identical, the cylinder was not completely remade or re-entered and you are looking at localized modifications made to the cutting guide indicators on the cylinder.The likely chronological explanations for this sequence of changes are these.

1. The original horizontal lines on the tab (selvedge) were etched or engraved onto the cylinder to serve as an alignment target for the automated mechanical guillotine or slitting wheels. In booklet production, these sheets are slit and sliced into strips before being bound and cut into individual booklets. Horizontal lines provided a reference point for the operators to verify that the vertical or horizontal spacing was advancing correctly through the finishing equipment.

2. The change to diagonal lines was almost certainly a remediation step to fix a doctor blade or paper-shredding issue. In web-fed cylinder printing, a long steel doctor blade scrapes excess ink off the surface of the cylinder, leaving ink only inside the recessed cells. Deep, perfectly horizontal lines run parallel to the edge of the doctor blade. As the blade passes over a sharp, continuous horizontal groove, it can drop into the groove ("blade dip"), causing ink to smear, causing uneven blade wear, or creating a continuous stress point that could nick the blade.The structural solution: Re-engraving or burnishing out the horizontal lines and replacing them with diagonal lines (or a hatched pattern) allows the doctor blade to glide smoothly over the groove at an angle. This maintains structural support for the blade and ensures clean wiping. It also prevents the high-speed paper web from catching on a hard horizontal line during processing.

3. The change back to horizontal lines indicates that while the diagonal lines may have solved a printing or tool-wear issue, they likely broke the finishing and cutting department's workflow. By 1979–1981, printing bureaus were increasingly relying on electric eyes and optical sensors to trigger automated cuts on high-speed booklet-finishing machinery. Diagonal lines alter the contrast profile and exact positioning needed for automated photoelectric sensors or manual cutting alignment. If a machine looks for a sharp contrast transition at a precise micro-second intervals, a diagonal line introduces a variable trigger point if the paper web shifts even slightly left or right.

To fix this without discarding an expensive cylinder, BABN engravers utilized localized re-entry or burnishing and tooling. They would burnish (smooth down) the diagonal lines on the tab area of the 72-subject layout and physically re-engrave or etch the horizontal lines back into the cylinder. Because this was done precisely on the outer selvage edges of the layout, the stamp designs and their existing micro-flaws on the rest of the cylinder were left untouched.

An example of what you are talking about would help.

Assuming it really is an engraved stamp, the transfer cylinder would not be normally reworked, but the master die. The master die would not have cut marks or alignment marks, but those would be placed there during the making of the printing plate.

Typically, one stamp of a single color and integral design (meaning the whole design is engraved at once, rather than a frame, vignette, value markers, etc.) is a master die.

The transfer roller is made with a single image

The transfer roller is then used to place that single image on the printing plate, multiple times, in proper place to make up a plate.

Any additional marks can then be added to the plate (Like plate number, alignment marks)

Here is a printing plate for a Cuban Airmail stamps, the color red element.

The master die would be a single engraving, transferred to the transfer cylinder, then rolled out 8 times to make a single plate.

You can repeat the process many times to create as many plates as you want. Any changes, either rework the plate, or, the master die.