In the printing history, the first printing process is the Letterpress printing process that is the direct printing process. Letterpress printing is the first invention of printing technology. In this process, the matter is designed on a metal or wooden block and this design is in the opposite form. after some years Offset Printing has been invented which is called indirect printing. Most of the newspaper industry printed their hard copy with offset printing. This time, there are different types of printing processes in the printing industry.
Why Offset Printing is an indirect Printing Process
In offset printing, there is a plate and printable matter is on the plate. The plate is of aluminum and its surface is a sensitive surface. The image is in the actual form on the plate. when the printing process begins in the machine, ink is transfer upon the plate on the image area. In the next step blanket cylinder and plate cylinder contact with each other. The plate cylinder prints the image on the blanket cylinder. The image of the blanket is in the opposite form and when the blanket transfers the image on the paper is in the actual form. So to complete the printing process, have to pass from three-step that’s why this is called the indirect printing process.
Making of the plate
As a man can not walk without his feet like that offset printing can not complete without a plate. The prepress department designs the image area on the plate. In the beginning, the aluminum plate was used but nowadays printer has two option they can use a polyester plate that is very cheap in cost than the aluminum plate. there is a problem with the polyester plate it is not fit for a long-running job but the aluminum plate is more reliable than the polyester plate.