Offset Printing

Offset printing is becoming more popular for its ease and quality. It’s known for a more significant number of prints as often the price is in the setup, so the cost per print gets cheaper. Therefore it’s better for larger quantities, for example, flyers, brochures and posters are best. 

What is the definition of offset printing? 

Offset printing, which is also referred to as offset lithography, is designed for larger quantities due to its big setup. It is a method of mass-production printing, and the main price is down to the main installation of the machinery. You’ll often find that the more you have, the cheaper each print will be. 

The method is having the imagine transferred through blanket cylinders and rollers to create a crisp image. 

 

What are historical facts about the print process? 

In the 18th Century, Czech Alois Senefelder invented lithography printing when he wanted a cost-effective method to copy sheets of music. 

Czech decided to use high-pressure forms of limestone where he covered the areas which need to be printed with a fatty printing-ink which are methods that are still applied today as we use vegetable oil-based ink to create that perfect image. The remaining areas were coated with an acidic solution made from a polysaccharide.

When they moistened the stone with water, the acidic solution would be clear of ink. Consequently, the fat area would be dyed. 

This method was a massive milestone for Czech that would ensure flat printing would be a process that would carry on for years. 

In 1904 the first prototype of an offset printing machine that worked alone by the American Ira Washington Rubel and the German immigrant Caspar Hermann, where they were inspired to mirror the indirect printing of a printing plate with a blanket cylinder made from rubber which was realised to the public in 1912 in Leipzig.

 

How do you put printing into practice? 

It all starts with the pre-press stage where the image is broken down digitally on a computer when each colour is separated into its own layer. 

Each of the images is lasered onto an aluminium coated plate

leaving an imprint of each colour layer which is then loaded onto a roller where the non-image is dampened with water followed by being pressed into a vegetable oil-based ink. The ink travels through several rollers before going onto the main roller on one side, which contains the image along with a blanket offset cylinder. The blanket cylinder is there to ensure a clearer and sharper image, and it’s where Offset printing gets its name. 

This is a massive part of the process, it’s a lengthy setup, but this why Offset printing is designed mainly for large quantity products.

If paper is the chosen surface, then tiny puffs of air are used to ensure one piece of paper travels through at one time. 

The first part of the journey is where the image will then go down the line and pass through several rollers, each covered with different colour ink, layering to create the images. 

Once the piece has completed, it’s a journey in between each coloured roller and blanket cylinder; is sent to the stacked pile. As it reaches this point, a transparent powder sprinkled on top to allow the ink to dry without transferring.

 

Why is offset printing different to other printing techniques?

The art of Offset printing is that the ink doesn’t get directly applied to the paper by a printing plate, like digital printing but is rollered from the plate to the surface. The difference to other printing techniques is that each of the four colour values Cyan, Magenta, Yellow and Balck is printed separately. 

It’s printed between an aluminium covered plate and a blanket cylinder rather than using multiple colours at the same time digitally to create a more perfect and high-quality image. 

 

What does it mean when it comes to printing onto glass bottles? 

An indirect offset print can be done to remodel a glass bottle to advertise a logo or a design. This process provides an effective method for a high-speed process of the multi-coloured line that can be done in large volume on plastic and glass bottles—leaving you with a constant print which is clean and bright across every piece. When offset printing is used products like perfume atomisers, it can leave a beautiful, flawless design. 

 

Offset printing has transformed the printing business by its speed and quality of transferring an image through rollers to create a crisp, flawless finish and can be printed onto a varied selection of materials as well as paper and glass.