Nowadays the most common method of printing is offset litho (lithography) which has been in use since 1875 when the first offset lithographic printing press was invented. However, lithography has been around since 1798, well before the press was conceived. Originally performed with stones, a crayon drawing on the surface of a stone was immersed in water and then dipped in ink. The ink adhered only to the crayon image and then the stone was pressed down on paper, to reproduce the image.
From stones to metal plates and printing cylinders
When the offset litho printing presses came along the same basic principle applied with metal printing plates being used instead of stones. A photographic image is transferred to the printing plate, and the image is then covered in clear varnish. The remainder of the plate is covered with resin. The plate is curved around a printing cylinder and pressed against rollers the first of which dampens the plate with water and the next with ink. Only the varnished part of the plate will attract the ink. It is then pressed against the blanket cylinder and the image is transferred. Pressed down on the paper, this soft rubber offset cylinder produces the print.
High velocity offset litho presses are fed by paper cylinders and capable of producing around 12 miles of print per hour!
The most commonly damaged printing press parts
As we have learned, offset litho printing presses rely heavily on printing cylinders and these are the parts that are most commonly damaged. New printing presses are highly expensive but when well maintained even the ancient ones are still in use today. However, finding spare parts for very old machines can be difficult and this is where Saras Process can help. We repair damaged Lithographic Printing Cylinders and refurbish old ones.
Prevention is better than cure
Conducting work on site, where practical, ensures that there is minimal downtime and once repaired or refurbished the printing cylinders will be back in optimum condition. Prevention is always best so we suggest a check on the condition of your printing cylinders to look for corrosion and damage to the cylinders.
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