Lim T.B*, Michael Tay Ming Kiong
American Academy of Forensic Sciences 55th Annual Meeting
Feb 2003, Chicago, USA. (poster presentation)
The purpose of this paper is to examine and compare the factory-cut edges of tabloid and broadsheet newspaper sheets and to ascertain the possibility of connecting separated intact newspaper sheets to the original copy of newspaper. Newspapers usually come in tabloid or broadsheet form, and a single copy may consist of several sections.
Most paper webs in a newspaper press are either approximately of 30 inch wide (single width press) or 60 inch wide (double width press). For a 30-inch web, a maximum of either four broadsheet pages or eight tabloid sheet pages can be printed, front and back. Twice these numbers can be printed if a 60-inch web is used. In a printing press unit, a newspaper usually requires more than one paper web. The printed paper webs are stacked on top of another and brought together across the RTF (Roller Top of Former) into formers. To produce tabloid sheets from a 60-inch web, two sequential longitudinal slittings are necessary: the first slitting at the RTF cuts through the centre of the web, producing two broadsheet webs; the second slitting at two separate formers cuts through the centre of each broadsheet web, resulting in a total of two pairs of tabloid-sized webs. Each pair of the webs is next folded back-to-back at the formers to re-form a single web. The two single webs are then combined into one (cross-association). This resultant web is guided and pulled through a folder by pins on cutting cylinders and cut transversely by a cut-off knife resembling a toothed saw. The final folding step results in copies of tabloid signatures.
To produce broadsheet newspaper, the first slitting is sufficient to separate the 60-inch web into two broadsheet-sized webs. A second slitting is not required, and the broadsheet webs are folded longitudinally to form two folded broadsheet webs at the formers. The two folded webs may be combined to form 2 newspaper sections before being cut transversely at the folder. When the press is running in collect mode, the copy is kept on the cutting cylinder by pins for one revolution whilst the next copy is being cut. Both copies are then released together as a single copy of broadsheet signature (4-section newspaper). In a high-speed production press, extra formers are added in the folder (as upper former & triple former) to allow incorporation of more than 4 sections in a copy of newspaper.
The authors have previously reported on the usefulness of tabloid newspaper sheets as crime scene evidence. The crucial requirement for linking intact tabloid newspaper sheets is the physical fitting of factory-cut edges of two “head-to-head” complementary sheets from the original copy. The cut edges are due to the second slitting at the former. These random edges fit like a jigsaw puzzle because the sheets are printed on the same paper web and adjacent to each other before the slitting. In contrast, for broadsheet newspaper production on 60-inch width web, a folded broadsheet web coming out from former may not be cross-associated with its complementary folded broadsheet web. “Head-to-head” complementary sheets are not therefore linked in an original copy. Furthermore, additional formers introduced in a high-speed production press may result in combinations of paper webs from different locations of slitting steps.
This project also studies the factory-cut edges on the tabloid and broadsheet newspaper sheet due to the transverse cut by cut-off knife in the folder unit. The cutting cylinders consist of a knife cylinder and folding cylinders. The folding cylinder contains a fixed set of pins to pull the paper web out of the former while a series of saw-toothed knives on the knife cylinder cut the paper almost simultaneously while it is rotating. Preliminary examination of newspaper edges cut by the cut-off knife shows a series of saw-toothed edges. The saw-toothed edges are found along both widths of a newspaper. Newspaper copies are examined for all the sheets to compare the similarity of cut edges from the top sheet where the cutting starts to the bottom when the cutting ends. Similar sheets of neighboring newspaper copies are also examined for repeatability of the cut edges. It was observed that even when a few paper webs are combined together, the stack of papers still has a small degree of flexibility and mobility. Initial penetration of the knife into the top few sheets produces cut edges that are more uniform; further penetration into bottom sheets creates more uneven and jagged edges. There are therefore variations in the cut edges of the similar sheets from one copy to another copy of newspaper. Adjacent stacking sheets in the same copy were examined and found to be similar in their profiles of cut edges. This feature can be used as basis for comparing the newspaper sheets and linking them to their original copy.
The preliminary finding of this project is that the matching of intact broadsheet newspaper sheets may be possible if the sheets are adjacent to each other. The printer of the particular newspaper should be consulted for the imposition of the newspaper on the day of the production. The newspaper sheets seized from suspected sources must be as complete as possible.