Layout Spread is the normal way a document is ordered during paste up so that sequential pages follow each other.
Printer Spread is the way a document is ordered so that they will be in the correct order when the printed pages are folded and trimmed.
Imposition is the process of creating Printers’ Spreads from Layout Spreads so that pages will be in the correct order when the sheet is printed, folded, and trimmed.
Type of Impositions:
Work-and-Turn Layout is a popular Printer Spread/imposition in which both sides of a sheet will be printed using the same set of plates. The plate is installed on the press, and the first run is printed.The front and back of the work is printed at the same time, but on different parts of the same side of the paper sheet. The work is then reversed or “turned”over with the gripper edge on the same side. The gripper is the apparatus which “grips” the paper sheet and pulls it into the press for printing. The sheet is then printed. The printed sheet is then cut apart to make two sets. Not having to change the gripper edge makes it much easier for the printer to get proper register. For this reason, work and turn is more widely used than work and tumble.
Work & Tumble Layout is another Printer Spread/imposition but it uses only one set of plates to print both sides of a sheet. The gripper edge is on opposite sides of the sheet. One side is printed and the sheet is turned from front to rear so that you are using the opposite edge as the gripper edge and then the second side is printed. The sheet is then cut apart to make two sets. Because changing the gripper edge means that adjustments must be made on press before printing the second side of the sheet, work and tumble is seldom used where close register is important. Also, because both ends of the sheet are used as gripper edges, extra paper must be allowed for margins.
Work-and-Turn (Left & Right) and Work-and-Tumble (Up & Down) Layouts save time and money by not requiring a plate change before printing the second side of the sheet. The imposition can save a lot of money, especially in four-color printing where each color, Cyan, Magenta, Yellow and Black, requires a different plate. As a graphics professional, it is always good to know where we can save production time and materials cost.
As one of the project requirements, students need to create a 6-Up or a 8-Up Work-&-Turn Sheetwise Layout with a pdf format, but don’t need to print it out.