The Process and Benefits of Offset Printing
The offset printing system came from the modernization of lithography and is the method most used by the printing industry since the second half of the twentieth century. The name offset means “out of place” because it is an indirect printing system where the message is transferred to the substrate by means of rubber cylinders.
The Printing Process
The offset system is planographic and printing occurs in a rotating manner, where the cylinders will drive both ink and paper. The matrix, cylinder with the image recording, remains moistened and receives the inkapplication. Because it is a system of repulsion, the regions protected by light (images) go through a chemical process that attracts the fat (ink), while the other areas (without printing) retains water.
The second cylinder is composed of rubber and is named blanket. Blankets are responsible for transmitting information from the matrix to the substrate (paper, for example).During the information transfer process, there is a third cylinder: the printing cylinder. He is responsible for pressing the paper so that it stays in contact with the blanket.
This process is necessary as it avoids smudges and excess ink that the cylindrical direct printing system can cause. The blanket, when leaning against the plate, absorbs the surplus paint and allows to transfer to the support only the necessary quantity.
Another issue is that the paint can wrinkle the sheet or even cross it, staining or gluing the next sheet, “danger” called the decalping. The decal can also occur if the forms are packaged or transported before drying completely, causing the loss of runs.
Offset printers can be classified as flat or rotating. Flatbed printers work from single sheets while the presses use paper reels.
Planes offer better quality, ideal for business card printing, folders, flyers, brochures, posters and books. Rotary printers are recommended for large print projects such as magazines and newspapers.
Benefits of the offset system
The offset system is considered one of the most efficient forms of printing, as it is fast for medium and large runs and prints on all paper types and weights, as well as some types of flexible plastics, such as polystyrene.
The most modern machines allow ample freedom of creation, allowing the variety of formats, colors and even aromas. They also have advanced controls of quality, color and registration, guaranteeing greater fidelity of reproduction.Now take a look at how these features of graficas em sp.