The most common type of printing today uses a method called offset lithography (typically shortened to "offset litho"), which is a whole lot simpler than it sounds. As we've already seen, offset printing simply means that the printing plate doesn't directly touch the final printed surface (the paper or whatever it might be); instead, an intermediate roller is used to transfer the printed image from one to the other. But what about lithography?
Lithography literally means "stone-writing," a method of printing from the surface of stones that was invented in 1798 by German actor and playwright Alois Senefelder. Lithography avoids the need to make a traditional printing plate, as you need for both relief and gravure printing.
Modern offset lithography printing presses use an updated version of the same basic idea in which the stone is replaced with a thin metal printing plate. First, the image to be printed is transferred photographically to the plate. The parts of the plate from which the image is printed are coated with lacquer (clear varnish), so they attract ink, while the rest of the plate is coated with gum, so it attracts water. The metal plates are curved around a printing cylinder and press against a series of rollers, which dampen them with water and then brush them with ink. Only the lacquered parts of the plate (those that will print) pick up ink. The inked plate presses against a soft rubber (offset) cylinder, known as the blanket cylinder, and transfers its image across. The blanket cylinder then presses against the paper and makes the final print.
Our products are all offset printing ink, if you have interest in offset ink, you can connect us for more details.
