What is Offset Printing?
Offset printing technology uses plates, usually made from aluminum, which are used to transfer an image onto a rubber "blanket", and then rolling that image onto a sheet of paper. It's called offset because the ink is not transferred directly onto the paper. Because offset presses run so efficiently once they are set up, offset printing is the best choice when larger quantities are needed, and provides accurate color reproduction, and crisp, clean professional looking printing.
What are the Advantages of Offset Printing:
1.Large quantities can be printed cost effectively
2.The more you print, the cheaper the price per piece
3.A large variety of paper types with custom finishes can be used
4.Special custom inks such as metallic and Pantone colors are available
5.Highest possible printing quality, with greater detail and color fidelity
How It Works
Offset printing is a commonly used printing technique where an inked image is transferred (or “offset”) from a plate to a rubber blanket, then to paper.
The offset process is a lithographic process. Lithoghraphy is a process based on the repulsion of oil and water.
An image that is offset printed is separated into its fundamental colors. (This example is assuming a 4 color job, ie. a brochure with text and images. There are times when there is only one or two colors or even six or eight.)
The brochure would be broken down into the primary printing colors; cyan, magenta, yellow and black (CMYK). Thanks to computers this process has become easier. The image is broken down into these four colors and four seperate plates are made.
A plate is made up of areas that are receptive to grease and areas that are receptive to water. The areas receptive to grease hold onto the ink while the other areas attract water and repel the ink.
These plates are then put on to a press. From the ink fountains, the press pulls in the ink and puts it onto the plate. The press applies great pressure to the plate and the ink imprints the image from the plate onto a rubber blanket. The image is then pressed onto the paper off the blanket to make a print.
When these four colors are printed onto each other the image comes back together and looks the way it did in in the inital PDF.
All this happens really fast and many impressions can be made from one set of plates. It is a very efficient process and lends itself very well to long runs over a long period of time.