Off-set litho printing is a process within the industry that many people do not know much about…
Fisherprint is an industry leader of pharmaceutical and corporate print. Therefore, our processes have to mirror the high quality of print and exceptional standard of service that we provide for our customers. With increased demand for sustainable, luxury print higher than ever, the machinery involved needs to match the same standard and quality!
What is Off-Set Litho Printing?
Traditional forms of printing can be very simplistic. Before more complex printing processes were introduced, ink was applied to a mold or printing stamp and simply applied to the paper. This process was more commonly reserved for leaflets and single sheet printing prior to technological advances within the printing field.
What Are Printing Plates?
Off-set litho printing – or off-set lithography – takes the manufacturing output and quality of printing to the next level… This method of printing begins with aluminium plates that are processed before they can be used.
A computer-to-plate process is involved… The plates are fed through a laser printer so the desired design can be marked onto them. Ultraviolet light and laser diodes are used to transfer the design of the intended print onto the plates. The ink is only transferred onto the marked template, so the desired design can be printed easily onto the required medium. The area outside the template is dampened because the water acts as a resist, so the transfer of ink is accurate and doesn’t smudge onto the rest of the plate.
The thermal plates we use are photosensitive between 830 nm and 1.070 nm. Each thermal plate has a high process stability and the ability to process even in daylight.
Printing Colours: What Are They?
The four colours used are Cyan, Magenta, Yellow and Black – or CMYK for short. Black is the key colour, so the letter K is used for the abbreviation. The Cyan, Magenta and Yellow plates are keyed together – with black being the base to them all.
These four colours make up the basis for every colour possible, allowing the printing presses to print easily without using more complex colours and processes.
The Off-Set Litho Process
The processed plates are wrapped around a cylinder and placed into the printing press. The press runs rubber cylinders – called blankets – and ensures they are constantly spinning to take the ink from the plates and transfer the marked design onto the paper.
The whole process is repeated four times for each printing job because each plate holds a single colour of ink.
The off-set litho method guarantees a perfect print each time and this is crucial, especially when you are mass printing! With the capability of printing up to 500,000 prints per plate, the process can be used for both medium and high volume jobs. Output can be increased 10-fold due to prolonged life of the presses and plates!
If the customer requires a finish where the ink is set into the paper, then the sheets will be fed – in layman’s terms – through an oven. The heat reacts with the ink and sets it into the paper, giving it a shiny, glossy effect. This is more common in web printing rather than sheet-fed printing.
There are two different types of off-set litho printing, both with different purposes and benefits. With only slight differences, it is best to know which one will suit you and your project.
Sheet-Fed Off-Set Litho Printing
Fisherprint can offer sheet-fed off-set litho printing – a process that involves sheets of paper being individually fed through the machine. Up to eight pages can be printed onto one single sheet of B1 paper, which can then be collated and stitched at a later date. These pages are then cut and trimmed to the size and shape of your choice after they have been printed.
Web Off-Set Litho Printing
Web off-set litho printing is slightly different. Larger machines are used, and these require large rolls of paper rather than individual sheets. This method is more commonly used for magazine or newspaper printing.