Offset printing: what is it?
Many people know the concept of printing. Many even have an idea of how newspapers or magazines print. However, such a thing as offset printing came into use recently.
In this article we will consider what it is - offset printing and understand the features of the technology of this type of printing.
What is offset printing
Offset printing uses contactless printing. In printing, this method involves the use of a form on which there are elements with spaces. For example, black and white photographs, as well as maps.
The principle of operation of this print is based on the use of ink, which falls on the paper, while passing through two contacts with the printing form. Offset printing is such a printing, which involves applying paint without contact with the paper, but with the help of a special cylinder. This cylinder is called offset.
In offset printing use two or more shafts.
- One shaft is offset, the other shaft is called the shape shaft. The number of shafts of the form depends on the complexity of the image.The form, as a rule, is a plate. A photosensitive coating is applied to this plate. The plate itself consists of an aluminum alloy.
- Paint is applied to the product form. At the completion of the development, all the lighted parts of the form attract water and repel any substance that has an oily consistency.
- As the shafts rotate, each of them is washed by water. Due to the rotation of the printing form is transferred to the offset shaft, and then falls on the paper.
Advantages and disadvantages
At the moment in the printing industry there are different technologies for transferring images to paper. Like any other printing, offset printing has its advantages and disadvantages.
The advantages include:
- very high print quality;
- reducing the cost of copies due to the cheapness of the process;
- print large circulation in the shortest possible time.
The disadvantages of printing include the need for reprints, as well as printing processing. That is, color proof, print form, color balance and so on. All this makes it impossible to carry out urgent orders (for several hours). In addition, offset printing is expensive relative to small runs.Therefore, to print offset printing in small editions is simply unprofitable.
Varieties of offset printing
The most popular and at the same time foremost direction in color printing is digital offset. What is offset? The essence of this method of printing is reduced to applying to a special form, which is installed in the printing press (machine). Also popular is the traditional offset printing, called photo-offset. Moreover, the latter type of printing can be called advantageous for relatively small replication. If we are talking about printing large quantities, digital printing is more profitable.
Also, offset printing is divided into sheet and roll. As the name implies, sheet printing involves the use of solid sheets, and roll - paper, which is rolled into a roll.