What Is Offset Printing?

If you’ve never heard of offset printing before, you may not be familiar with everything it involves. Offset printing is how we got our start, we’ve been working with it for decades.

What Does Offset Printing Mean In Printing?

Offset printing, sometimes referred to offset lithography, is a printing technique for mass-production printing in which the images on metal plates are transferred to rollers, rubber blankets or cylinders, then transferred to paper or other printing materials. With this printing method, both sides of a sheet of paper are printed at the same time.

The rubber cylinder itself gives you a ton of flexibility, allowing you to print on metal, wood, cloth, leather or rough paper.

Understanding Offset Printing

With this printing type, the print is not raised above the surface of the printing plate (as in letterpress) nor is it sunk below it (like intaglio or gravure printing). Instead, it’s flush with the surface of the plate; thus offset is classified as a planographic method of printing.

Offset printing, which is a development of lithography, is based on the principle that water and grease do not mix. Due to this, a greasy ink can be deposited on grease-treated printing areas of the plate, while nonprinting areas, which hold water, reject the ink. The plate is commonly made from zinc or aluminum, or sometimes zinc and aluminum together, with the surface treated to render it porous and then coated with a photosensitive material. Exposure to an image hardens the coating on printing areas; the coating on nonprinting areas is washed away, leaving wetted metal that will reject ink.

Modern offset printing is done on a press composed basically of three rotating cylinders:

  • Plate Cylinder – This is where the metal plate is fastened.
  • Blanket Cylinder – This is an impression cylinder which pressed paper into contact with the blanket cylinder.
  • Plate Cylinder – Contacts moistening rollers which deposit moisture in granulations of the metal.

A series of inking rollers then pass over the plate, and the ink is rejected by the water-holding areas and accepted by the greasy image. The inked image is transferred to the rubber blanket and is then offset to the paper traveling around the impression cylinder.

What Printing Type Should A Business Choose?

If you’re a business owner and you have printing projects due, you may be wondering which one of these printing methods are going to be best for you to use.

If you have experience with printing technology or printing in general, you’ve likely already thought about Digital Printing vs Offset Printing, after all, these are two of the most common printing methods used today.

Traditional offset printing is a print method that uses aluminum plates to transfer ink onto a rubber sheet (this is usually called the “blanket”)  From there, the image is rolled onto the printing surface. This printing method is considered “offset” because the ink is not transferred to the paper directly.

Offset is usually the best option when printing large quantities. Although there is a significant initial cost to set-up the equipment, additional units become relatively less expensive as the quantity of prints increase.

With digital printing, ink is transferred directly onto the surface. Instead of needing aluminum plates and rubber blankets to transfer an image, digital printing uses liquid ink during the production. Traditional home inkjet printers are one of the most common digital printing methods.

Digital printing needs no manual setup. This printing method is effective for use with smaller quantity runs. In fact, it is far more cost-effective than offset printing for low volume projects.

Since no set-up is needed, digital printing is a quick process, capable of completing projects on short notice or finishing a job when a deadline is quickly approaching. Digital printing also offers a wide range of customizations to fit your needs.

Which Print Method Is Best?

  • Quickest Turnaround Time – Digital
  • Most Accurate Color Match – Offset
  • Cost Effective For Small Runs – Digital
  • Cost Effective For Large Runs – Offset
  • Easy Proofing – Digital
  • Ink Diversity – Offset
  • Diversity Of Printing Services – Offset
  • Single Unit Customizations – Digital

 

No matter what print method you decide to choose, we’re always here to help. If you need help choosing a printing type for your project or have a general question, be sure to reach out.