Web+Printing

**What is Web Printing?**
Web printing is a form of offset printing (a method of printing where images on metal plates are transfered onto rubber blanket or rollers, then onto the print media) but a continuos sheet of paper gets fed through the printer and is cut after printed. There are two types of web printing, high speed commercial web, and small narrow web. High speed web (900-3000 feet per minute) is use mostly for high volume prints and uses heat set, where the inks dry by heat and prints on both sides at the same time. Small narrow web (300-900 feet per minute) is mainly used for the smaller valume printing and uses cold set ink, which dries by air and absorption into the paper and does one side at a time. "Half-web" means the width of the web is in he 25" range, and "Full-web" mean the web width is in the 33"-56" range. All web presses have in-feed, printing, units and delivery. Web printing is the best way to print any high volume prints like newspapers, books, magazines. Web printing is the fastest of prints and has excellent product quality and it mostly finished in-line.

Here's a video showing how the web printing process works. media type="youtube" key="JjAu7bn5shs" height="315" width="420"

**What it is the process of Web Printing ?**
The process of Web Printing happens in three stages; Infeed, Printing Units, and Delivery. During the infeed stage, there is a steering device that controls the way the paper enters the printer. The paper is delivered to the machine in this stage ten sent to the splicer that cuts the beginning and end of each sheet of paper. This process is helped by the tensioner which maintains the proper tension and enables paper to travel through the press smoothly. In the printing stage, there are several printing units. There can be three up to nine or more. Each unit contains an inking system, dampening system, plate cylinder, blanket cylinder, and an impression cylinder. The final stage of delivery consists of a variety of devices. Two examples of these are a simple sheeter that cuts moving web into sheets of the required size and a combination sheeter and folder that folds web into signatures and trims them to size.



**What are some of the pros and cons of Web Printing?**
__PROS__ -consistent high image quality -produces sharp and clean images and type more easily -longer printing plate life -offset printing is cheapest method to produce high quality printing

__CONS__ -slightly inferior image quality compared to rotogravure or photogravure printing -sensitivity of printing plates misprinting if not cared for -time due to setting up the printing machines

**What is Web Printing used for?**
Web Printing is best suited for cost-effectively producing large volumes of high quality prints in a process that requires little maintenance. It is one of the most common ways of creating printed matter. Newspapers, magazines, brochures, stationary, and books are a few examples of applications printed with web printing. This form of printing is of benefit to long run printing jobs up to 20,000 impressions.



**Inks**
There are four colours in web printing. Cyan, magenta, yellow and black.

Letterset are mainly used with offset presses that don't have a dampening systems and uses imaging plates that have a raised image.
 * Letterset**

Waterless inks are heat resistant. They're used to keep silicone based plates from showing toning in non-image areas. Usually used in waterless direct imaging presses.
 * Waterless**

Single fluid inks are a newer ink. It uses a process allowing lithographic plates on a lithographic press without using a dampening system during the printing process.
 * Single Fluid**

Ink and water balance is very important in web printing. If they are not properly balanced, the press operator may end up with problems that will effect the quality of the finished product. When properly balanced, the the job will have the correct ink density and should require minor adjustments.
 * Ink/water balance**

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 * Sources:**

http://en.wikipedia.org/wiki/Offset_printing http://whatis.techtarget.com/definition/0,,sid9_gci1197408,00.html http://www.dynodan.com/printing-process-explained/web-offset-printing/index.html