1. Image Area: Every sheet will have some areas where the images and other texts will be printed. The image will be surrounded by white margins all around. The sheet where the images and texts are to be printed is termed the image area. Similarly the printing plate which has the images and texts that will take the ink to transfer them is called image area of the plate. The entire areas which will be blank and non printable will be called non image areas.
2. Imposition: Whenever a book containing several pages are to be printed, they will not be printed as individual sheets. The entire composed matter will be first separated in page form giving them the page no, headings, etc. The pages will then be so arranged in a laid out format that when a sheet is printed back to back with the laid out composed matter and then folded and trimmed to the ultimate book format, all the pages thus printed, folded and trimmed will have correct sequence of pages i.e in readable sequence. The process of organizing the pages for printing as stated above is called layout making in Offset Printing and Imposition in Letterpress Printing. After organizing the pages in a layout or Imposed ( assembly of composed type material into a frame in page format and locked) , when the book is printed, sheet after sheet, the pages will appear in sequence. Since printing the voluminous job as individual pages will be very costly and time consuming the imposition is adapted. The imposed pages will be printed on a bigger sheets to a pre-prepared layout. In short the Imposition is the process of arranging the individual pages on the sheet of paper so that after they are printed, folded and trimmed, the resulting pages will sit back to back correctly and be in the proper order. However note that in DTP (Desk Top Printing) the pages are normally printed as single sheets only to avoid confusion in back to back printing.
The process of transferring the text and images from the plates or blocks on to the paper or other substances through two mediums is called giving impression. This in short means pressing the design and text elements on to a printable medium. During the process of impression only one printable medium will pass through the impressing medium. When 500 or 1000 copies are to be produced, the sheets will get 500 impression or 1000 impression if individual pages are printed. When the same page is made up in multiple ups in a sheet and then printed the no of impression will depend upon the no of ups the pages have. Supposing each page contains 10 pages then the no of impressions will be 50 for 500 copies and 100 impressions to produce 1000 copies.
While on the platen printing machines the impression device will be in the form of a flat surface called Impression frame, on the high speed rotary machines and web printing machines the impression will be given by the device called impression cylinder which will be in cylindrical form.
4. Impression Cylinder :
A Cylindrical device on the printing machine that pushes paper against the plate or blanket or assembled composed matter locked in a frame to ensure that the design elements on them gets transferred on to the printable medium uniformly. On most of the machines series of grippers that hold the printable medium in registered position for printing are kept attached to the Impression Cylinder. On Intaglio machines the impression Cylinders are covered with a special fabric based material to press the paper effectively against the plate cylinder.
5. Ink Fountain:
One of the vital parts, in the form of a duct or tank of the printing machine from where the Ink required for printing the print material will be supplied to the plate or blocks for printing through series of intermediatery rollers which grinds the ink further for smooth flow.
6. Imprint :
It is mandatory requirement in all the countries to print the publisher's name, address, edition etc in all the printed books of any nature, either in separate page- generally opposite to half title pages, or opposite to the contents page- or in the last page of the book. Such printed matter is called Imprint. Besides providing such information on the printed books, it is also mandatory to print such information at the bottom of single sheeted posters, leaflets, pamphlets etc to identify the printer who printed the matter.
7. Ink Jet Printing : The technique of spraying droplets of ink jetted through computer-controlled nozzles on an printing machine for getting the print is called Inkjet Printing. The liquid stream breaks up into droplets and create the image. Ink-jet printers are capable of producing high quality print comparable to laser printing. The inkjet printers produce the photographs not as halftone images but as continuous tone image whose resolutions may even go up to 600 dots per inch. The greatest advantages of inkjet printers are, quiet operation, capability to produce color images comparable to photographic quality at low cost. One can print labels, posters, vehicle and floor graphics, apparel decoration and just about any sign imaginable through Inkjet printing. Varieties of Inkjet printing machines- both table top model and stand alone model- are available in the market. However for printing huge no of copies, say 500 or 1000 or more, Inkjet printer will not be economical.
8. In-Plant Printer :
The big industrial houses have their own small printing presses to bring out their activities and function in the form of a printed booklet from time to time or get their entire stationery and print requirements executed within their own organization. The main advantage of having such an in-plant printing is that it will require only less man power operate, capable of generating faster information through print media as they will be situated within their own organization. Since the in house printing activities does not include profit the out put turned out is always cost effective.
9. Intaglio Printing :
It is a highly specialized process that gives the document a very high quality relief images perceptible by touching with the fingers. This is based on one of the oldest processes in which the prints were taken from etched copper, zinc and steel plates to give relief image. This process of printing is widely used as the one of the best security features. The oldest process has been subsequently improved upon drastically to cause relief images from different technology generated processes and plates printable through the rotary printing presses.
The major disadvantage of this process of printing is that the multi color images can not be reproduced by this process, and only cut color printing, that too with limitation is possible to reproduce by this process. The reason being, the impression needs to be given with high degree of pressure. The high pressure causes the ink from the recessed image get adhered to the paper. Again if the same sheet of paper is fed to give another impression, the relief effect generated by the first print operation will go down or will become plane due to high degree of pressure given on the paper.
The basic working of Intaglio printing process is as follows.
- A highly stout ink is pushed into the depressions of the plate and the surface is wiped clean, leaving ink only in the recessed areas.
- The paper will be placed over the plate and substantial pressure given so that the paper is forced into the depressions of the plate to produce a richly inked impression.
- On automatic machine the highly stout ink is applied to the recessed areas by specially prepared image cut rubber based rollers.
- The printed sheets can not be quickly used and relief images will have to be allowed to dry for at least 48 hours.
............Additions to alphabet I to be continued under I/2