21. Scanner:- Various types of Scanners are in use in printing. One of the scanner is a device that captures the images and converts them into digital image and stores it in the memory of a computer, which is further processed for printing.
The other Scanner is the one which color separates and produces printable negative or positive or even a metal block meant for printing. Essentially the Scanner is a device that scans an image, capture them and store it in its memory. From memory, the required format- negative, positive or plates - is derived based on the system that is attached with it for a particular function.
A Scanner can be used to make direct negatives or positives or to capture the image to make modification, improvement and colour correction etc before using it for printing. The latest development in the print industry is the Online print inspection machine where the scanner plays vital role. The the actual images under print will be Scanned to capture the correct print image and store them in memory console fitted on the machine as golden image which compares the printed images online with the stored image and indicate the defective areas or defects to immediately take necessary corrective action while the machine is running.
22. Sizing : This term is for Paper making process and refers to the material which is used during the paper making process to smoothen the surface of he paper and to fill up the inter woven fiber porosity. This will also prevent the paper from absorbing too much moisture. Sizing also protects the fibers from breakdown due to oxidation and add strength to the fibers . Sized papers show a considerably higher strength.
23. Stripping: Stripping means assembling elements of print material negatives to make them as one format or one page to use in printing. Stripping is also called a film assembly or an image assembly. How will the stripping work carried out?
Some of the print jobs may have both illustrations and text material in each page. If the illustration is a line work, it can be pasted along with the text matter and negative can be straightway made for further processing. If the text matter and continuous tone work is to be combined for printing, first the continuous tone photo has to be converted to halftone and clubbed with the text material in which the process of Stripping comes in. How the text material with illustration is combined and how does the tripping plays the role?First a dummy (Model) is made indicating the text matter and position of the illustrations. Thereafter a master layout to actual final print job size is made on a sheet of Astralon sheet flat film (or any other highly dimensionally stable film base) which will act as a guide to position the negatives containing the text material and the illustrations and joined together with cello tapes and further processed.
The process of Stripping for a single page print material or a book is the same. Let us see the process.
Supposing it is the case of a book work for Offset printing. The entire manuscript will be composed and the text matter will be pasted (laid out) as each page on a good quality paper which will be kept on the Master Layout sheet to place the matter in correct position and to copy the Register marks and cutting marks. Sometimes when the number of pages are more, the base sheets on which the text matter is pasted for page make up will be printed exactly matching the Master layout the pasting of the text material will be carried out on the printed sheets. The page nos will also be given. In the case of photo composing machines where you get the direct negatives, the space for pasting the illustrations will also be given and composing of the text continued.
Each laid out sheet will indicate the place where the illustration will appear. The exact space will be provided on the laid out or composed pages for inserting the illustration.
The laid out text matter along with the register marks will be processed to make negatives if the laid out pages has been manually prepared. The places where the illustration appears will be blank.
The next step is to make negatives from the originals supplied.
Once the illustration negatives are made, page by page the illustrations will be combined with the text material by cutting windows and pasting the illustration (negatives) in the said window and cello taped to hold them in position and further processed (See the illustrations to understand the process of Stripping) .
24. Screen Ruling : See Halftone to read further. The screen ruling indicates number of lines per square inch that makes the halftone screen. The finer the screen ruling, the finer the halftone dots will be produced
25. Streaking: This is one of the printing defects that is commonly witnessed in Offset printing. The streaking will show a dark streak of image in rows at a particular point of run. This defect could be due to several reasons such as improper Cylinder bearer adjustment, worn out gear, worn out bearings on rollers or cylinders or may also be due to ink drying. If the inking form roller is not properly set with plate cylinder it can also give a bounce and cause this problem.
26. Sheet fed machines: Machines on which only cut sheets of paper can be fed for printing. The Sheet Fed machines can not print paper reels. In sheet fed printing machines two varieties of feeders are available. One is Continuous feeder in which the sheets travel one below another without gap between each sheet fed. In Sheet fed machines, only when the after the back edge of the first sheet leaves the feed board, the second sheet will enter into the feed board. The difference between the two printing machines will tell upon the speed at which the sheets are printed.
27. Serigraphic Printing: Serigraphic Printing is another name given to Screen printing. The screen printing was also called Serigraphic printing because the word Serigraphic is a mixture of Latin and Greek word meaning Seri =Silk and Graphic means drawing. Since Screen print is basically a stencil printing process and therefore any stencil printing process is covered by the name screen or serigraphic printing.
...........Additions to alphabet S to be continued under S/6