MyPrintingTutorials.com-Printing Tutorials Offset Printing Digital Printing A Guide to Offset and Digital Printing

Digital Printing has become a very profitable business especially when you have to print in small quantities. Digital printing could mean inkjet or laser printing. As for now the benefit in cost is in laser printing. At the lowest end will be the color laser copiers that are being sold in the market by various manufacturers. At the high end will be the digital production printers offered by companies like Hp and Xerox with printers like the Hp Indigo and the Xerox iGen4. The Hp Indigo starts from about Rs. 8,000,000/- (Eighty Lakhs or Eight Million Rupees). For small printers the Digital presses like Xante Illumina, Xitron Prism and the Xerox DC242 may be more feasible. The Xante Illumina and the Xitron Prism comes under Rs. 800,000/-. The Xerox DC242 starts from Rs. 1,400,000/- (Fourteen lakhs). All these printers print 12″x18″ size paper. The cost per page come around Rs. 8/- irrespective of ink coverage under the company policy where we have to give this amount to them. The cost of digital paper comes to about Rs. 3/- per 12×18 inches sheet. These small digital printing presses are suitable in India for only around maximum 200 tabloid pages per job because the cost of offset color printing is very low here. However for small repeat jobs they are very profitable. The quality of the color copiers at a lower range are not that acceptable for a print shop.

Posted under Digital Printing

The three roller Kompac Dampening that we use in our Autoprint machine has taken our color printing at another level. Printing of solids and other complicated jobs proved to be quite a disaster previously. The conventional dampening with cloth is not at all advised while going for color. This dampening causes huge color shifting from sheet to sheet and scum is also a problem. The Kompac II with the color mate removes these problems. As for now we don’t have any scum problem in the printing and sheets dry quicker. Color shifting from sheet to sheet has also been greatly reduced and we don’t have problem printing of solid areas even though our machine has only two ink form rollers. The stress that the machine operator used to have has also been reduced. Now there is quick ink and water balance in the machine. The dampening system is compatible with all Autoprint 15×20 machines. The price from Autoprint is around Rs. 120,000/-

Posted under Offset Printing

Dot gain is a phenomenon that happens when the size of a printed dot increases during the printing process. This cause the quality of the final printed matter to be distorted with respect to color. To a large extent this can be controlled after careful monitoring of the whole process of printing. A densitometer will be required to predict dot gain more accurately. Dot gain is controlled better in a CTP process than in a film to plate process. During plate exposure and processing there can be dot loss instead of dot gain if the plates are over exposed. In the Technova Polyjet system there can be dot gain or loss in the film if the ink density adjustment is not accurate in the Epson printer. At our press we use a ink density setting of 40 percent for 1440×1440 dpi at 125 lpi using a linearization file for 125 lpi.

Posted under Offset Printing

After a file has been designed and completed, it is to be saved in TIFF format in Photoshop at 300 dpi in CMYK mode for commercial printing. Various profiles may be used to reduce dot gain in printing. For web offset printing 150 dpi may be sufficient though some web offset printing may go up to even 250 dpi. Dpi (dots per inch) as a rule has to be about twice the lpi (lines per inch). Sheet fed offset printing is normally done in 150 or 175 lpi. Therefore it needs about 300 dpi files. Web offset on the other hand is done in about 75 lpi to 100 lpi so they may need only about 150 to 200 dpi files. However all files have to be in CMYK mode.

Posted under Offset Printing