Wednesday, September 14, 2011

Printing Methods for Custom Printed Paper Rolls

We are often called upon by our customers to produce a wide variety of custom printed paper rolls. For this reason, I thought a post that discusses the different printing methods available to us would be helpful. This post will give you the basic differences between the conventional printing processes used today for point of sale paper rolls, kiosk paper rolls and many other thermal paper roll applications. The types of printing that will be explained in this post will be Letterpress, Offset and Flexography.

Letterpress is the oldest printing method of printing. Invented in 1440, letterpress uses a relief (or raised text and images) printing plate. A reversed image is inked and then pressed into a sheet directly from the plate to paper to obtain a positive or right reading image. Letterpress is a very unforgiving medium, therefore printers must understand its capabilities. For instance, since most letterpress equipment prints only one color at a time, printing multiple colors can be challenging. The inking system on letterpress equipment is less precise than on offset presses, which can pose problems with some detailed graphics, small type or very fine halftone because when surrounded by another color, they can fill in with ink and lose definition. However, a skilled printer can overcome most of these problems.

Offset printing is a commonly used printing technique in that uses flat (no relief) thin metal plates in which the inked image is transferred (or "offset") from a plate to a rubber blanket and then to the printing surface. When used in combination with the Lithographic process, which is based on the oil and water don’t mix rule, the offset technique employs a flat image carrier on which the image to be printed obtains ink from ink rollers (Oil Receptive), while the non-printing area attracts a water-based film called "fountain solution" (Oil Repellent), keeping the non-printing areas ink-free. An advantage of offset printing over letterpress is that it produces higher quality, sharper images because the rubber blanket used conforms to the texture of the printing surface.

Flexography (often abbreviated to flexo) is a form of printing which utilizes a flexible relief plate. It is basically an updated version of letterpress where the ink roller transfers the ink to the Anilox Roller, then to the Plate Cylinder and then to the Impression Cylinder and then onto the paper roll or other subtrate. This method can be used for printing on almost any type of substrate including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging (it is also well suited for printing large areas of solid color). Laser-etched ceramic anilox rollers play a role in the improvement of print quality. Full color picture printing is now possible, and some of the finer presses available today, in combination with a skilled operator, allow quality that rivals the offset process.

Other variables that will come into play when choosing the right printing method for your custom printed paper roll include print volume and the width of the equipment. Narrow presses are better tailored to run low volumes and wide width presses to run high volume jobs.

I hope this gives you a basic idea of the options that are available for your custom printed roll paper needs. If you have any questions on the printing process and how we could help with a custom printed project, please feel free to call us to discuss in more detail.