The Register-Hand’s Duties [Rembrandt]
by Rob Clayton
It was quite usual for the register-hand, the ‘second in command’ on the press, to be a well-experienced gravure printer of many years standing. With an intake of printers from letterpress with no previous gravure experience, it would be some years before they had enough experience to take on that role. The control of register, in the period before automatic register control systems were introduced, was a true art and a real challenge on the old presses in use at Rembrandt.
The gravure cylinders were all correctly sized for diameter, the importance of this probably having been determined in the early days of multicolour printing. The importance of correct sizing and sequencing of the rubber impression rollers was also fully appreciated at Rembrandt, and involved the careful circumferential measurement of each roller and the subsequent positioning of the rollers, with the smallest in the first printing unit and the others increasing in diameter on their way through the press. A difference of 1/32” in circumference was sufficient to give a continuous register drift during the run. It is remarkable that almost thirty years later, in some gravure houses this writer visited, the importance of having the impression rollers either identical in diameter or stepped in increasing diameters was not recognized. But the diameter of the rubber impression cylinders was critical. The correct friction between surface contact of cylinder and deformed rubber roll at point of impression could only be achieved if a positive draw was present. If the impression rollers were not sized, any variation would influence register.
Engineers in particular ridiculed this need, on the basis that the impression roller, being without gearing to the gravure cylinder, was friction-driven by the pressure from the gravure cylinder, so the roll diameter could not influence register. Printers knew better and could easily prove the point by switching over two impression rollers. This proper sequencing of the impression rollers to compensate for and minimize the register drift continued to be done even after the introduction of automatic register controls.
Automatic register controls were often able to compensate for, and minimize, register drift to within the acceptable limit of approximately +/– .004”, or the distance between the walls of a cell. The register-control equipment manufacturers were quite adamant, however, that if a press was not inherently stable, then the equipment would be unable to maintain control to the desired tolerance. The lack of register stability was emphasised by the flashing lights on the control units, because the equipment was continually correcting registration. The symptom of incorrect sizing either of gravure cylinders (very unusual) or of rubber impression rollers (unforgivable) was register drift, this being the image moving out of register to be followed by the image moving back into register a few seconds later without any input from the register-hand. One might expect that if one roller was oversize, it would draw a few extra millimetres of paper through the press on each revolution, and the register would continue to go further and further out of register as time went on. Alternatively, either the tension in the web would increase until the paper broke, or the paper would not be drawn through the following print unit fast enough and it would sag between the units. This did not happen, of course, the reason being that when the tension within the units increased to a certain point, the print units on either side equalised the tension for a few seconds, at which point the process restarted and the register drifted again.
Register-hands were responsible for ensuring the correct sequencing and insertion of the impression rollers, a duty they carried out faithfully. During job changeover, the register-hand supervised and took part in the complete changeover with the exception of the folder, which was the duty of the chargehand. The register-hand, together with the ink slinger and all the Natsopas, would work as a team to wash up and ‘make ready’ the press. Supervised by the ink slinger, one team would complete the wash-up and removal of the cylinders. They would then collect the cylinders for the new job by loading them onto small press trolleys, and the ink slinger and register-hand would identify the units for each cylinder and impression roll, and then supervise their installation by the Natsopas. While the ink slinger prepared the ink for the new job, the register-hand would supervise the setting-up of the ink trays and the coarse registration of the gravure cylinders; when the ink slinger had inked up the units, they would jointly insert new doctors and set them up within the units. The press would be webbed up with the folder disconnected from the press by a clutch system. Under the control of the register-hand, the units would be started on crawl speed and each unit would be adjusted for printing and register until the printed web was in very close register. It was then available, ready for the chargehand, who would be close to finishing his work on the folder. The register-hand, as a matter of pride, liked to have his printed web ready for the chargehand by the time the latter had finished preparing the folder. The start-up of the new job was supervised closely (and taken very seriously) by the chargehand.
During the course of the production run, the register-hand continuously monitored the register by visually scanning the printed web prior to its going into the folder. Things beyond his control would often cause the register to shift. For instance, a mill-joint in the paper could be enough to cause slight misregister, particularly so if the following joint was from a different parent reel from that used in the web prior to the joint. [See a more detailed explanation at the end of this article. – Ed.]
One particular cause of register change was when the Natsopa ‘oiler’ made his regular lubrication tours round the press. Even the application of grease to the open brass bearings supporting the gravure cylinders could have a major effect on register. The wear to the gear teeth over many years of use made them susceptible to backlash, and the new grease often reduced the friction between the cylinder shaft and the bearing with the result that web tension was changed and the register shifted significantly.
Because the register-hand was watching the running web continuously, he was often the first to see doctor marks developing, and as part of his duties he would bring the marks to the attention of the ink slinger, who then did whatever was necessary to eliminate them.
Everyone worked as a team and it was a stress-free workplace with virtually no direct supervision from departmental management.
Mill joints: Paper mills produce reels of paper two or three times the width of those used on a web press. Being made from natural ingredients, paper has uneven thickness across its width when it comes off the dry end of the paper-making machine, so when a parent reel is slit down at the mill to make three or four press reels, each of those reels can have slightly different characteristics. These differences usually cause no trouble during printing, one reel following another smoothly throughout the press run. But very often, the mills must make up press reels from mill reel ends, perhaps to a specification of no more than one or two mill joints per press reel. If a press reel is made up from two mill reels that have been produced days apart and from different positions across the width (where the substance weight can vary quite a bit), register will be affected when the paper joint goes through the press.