Offset printing is the most popular commercial printing method today, helping businesses generate top-quality print work in bulk. While the technique has been around for years, recent technological advancements have made it the go-to choice for businesses with large printing needs.
If you’re here, you’re likely considering this method for things like magazines, brochures, paper labels, packaging, or your next printing project. No matter what you’re working on, it’s important to understand how offset printing works and what makes it a great choice.
So, in this article, we’ll dig into everything you need to know about offset printing to help you decide if it’s worth a shot!
What is Offset Printing?
Offset printing, more widely known as offset lithography, has been around since the 19th century. To this day, it’s the go-to choice for artists, publishers, advertisers, photographers, and businesses globally. In fact, the global offset printing press market is expected to reach $3262.1 million by 2028, with a CAGR of 3.33%.
The name ‘offset’ comes from the fact that during the process, the ink isn’t applied directly to the paper. Instead, it first transfers to a rubber blanket before being applied to the final material. The process uses a series of rollers, called cylinders or drums, to apply ink to the paper.
Typically, offset printing is used for production runs of over 1000 pieces simultaneously. This means it’s ideal for large print jobs, but fortunately, it can also handle smaller projects when needed. Regardless of the quantity, offset printing stands out as a high-quality, reliable choice for different printing needs.
Some offset printing presses use silicone layers that repel ink instead of water, called “dry” offset presses.
How Does Offset Printing Work?
While offset printing has evolved a great deal since its inception, it still operates on one basic principle – grease and water don’t mix. However, how the process works requires a thorough understanding of the concept.
First things first, offset printing uses three main cylinders that work together to facilitate the process: plate cylinder, offset blanket cylinder and impression cylinder. This multi-step process also includes etched metal plates and water-repellant inks as the key elements.
First off, the plates are carefully treated so that oily ink sticks to areas containing text and images. Meanwhile, a fine layer of water solution on blank plate sections repels the oil-based ink so they remain empty spaces. This ensures that only the intended parts of the plate receive ink, which leads to the desired transfer of ink onto the printing surface.
Next up, the blanket cylinder, wrapped with a rubber blanket, rotates in the opposite direction as the plate cylinder. As both cylinders meet, the water is squeezed away on the plate, while the ink is transferred to the rubber blanket, which imprints a mirrored version of the print design onto the blanket cylinder.
Finally, the final roller, or the impression cylinder made of clean steel, takes over. This cylinder rotates in the opposite direction as the blanket cylinder and presses the paper against the rubber blanket to transfer ink onto the printing surface. At this point, the image on the surface perfectly mirrors the one on the plate, which concludes the printing process.
Offset Printing Process Step-by-Step
While the process seems pretty much mechanized, the operator must be on his feet to make timely changes when required. This requires a thorough understanding of printers and the offset printing technique from the beginning to the end.
So, to help you better understand how offset lithography works, we’ve broken down the process into simpler stages:
The pre-press stage is the first step in lithographic printing, which involves design, layout, and typesetting to prepare digital files for printing. It ensures files are the right size, format, and color (CMYK) and eliminates any errors that might interfere with the process. During this stage, you may even consult a product specialist for guidance and high-quality prints.
Once everything is in order, the printing stage begins, where specialized offset lithographic machines transfer ink from plates to cylinders and then to the printing surface. The good news is that these machines can handle different paper stocks, ink types, and plate sizes to deliver exactly what you need.
Finally, the printed materials are finished and prepared for distribution during the post-press stage. This stage involves two key steps to ensure the final product meets the quality standards: cutting and finishing. The former trims the edges to give the product a professional look, while the latter adds special touches like coatings or embossing.
Soon after the printing process wraps up, it’s time for quality control and inspection to make sure the results meet the customer’s expectations.
To maintain top-notch quality, post-press technicians often use different tools and techniques to monitor the finished products. For instance, they use colorimeters and densitometers to measure color accuracy and consistency, which in turn makes sure the prints look exactly as they should.
Frequently Asked Questions
When it comes to offset printing, the possibilities are limitless. Some of the products you can use offset printing for include retail packaging, posters, flyers, books and magazines, stationery, postcards, direct-mail pieces, and paper-based labels. However, the technique works best.
Offset printing wins over when it comes to producing high-quality prints, especially for larger sizes and large quantities, such as e-commerce packaging because it lowers the overall cost. In contrast, digital printing is generally preferred for short-run production where speed is crucial since it offers convenience and quick turnaround times.
While offset printing can be done on various paper types, some materials are the most suitable for this printing technique. For instance, uncoated offset paper is perfect for offset printing because its coarse surface absorbs printing inks and dampening solutions more effectively than the rest.
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