A Review of Different Printing Methods
Which printing method is ideal for your project? With so many different printing techniques and technologies at your disposal, it can be difficult to decide on which process to use. Is traditional offset printing the right option for you? Will digital printing do the trick? What is flexography? Read on to learn more about the basics of each printing method.
Traditional Offset Printing
Typically, when you hear someone talking about “traditional printing,” they are referring to offset printing. In this printing method, printers will prepare an aluminium printing plate rendering of the image that needs to be printed. The plate is inked so that the image can be transferred (or offset) to a rubber blanket. Finally, the rubber blanket transfers the image to the printing surface. Sometimes, offset printing is paired with lithography. In the offset lithography process, the non-image parts of the printing plate attract a water-based film which helps to keep those parts of the plate free of ink. This process is effective for maximising print quality and minimising bleed.
For offset printing, a different plate is created for each colour to be used. Usually, there are four colours and therefore four plates. The colours are cyan, magenta, yellow, and black—often abbreviated as CMYK in the printing community. (Black is “Key” in this abbreviation.) Because the process of producing multiple different plates for a single printing job is relatively time-consuming, offset printing tends to be used mostly for high-volume printing jobs. Common uses include newspapers, books, packaging, and promotional materials like brochures. Offset printing is particularly popular for food packaging, where companies will often use six colours instead of just four.
Offset printing might be the most “traditional” form of printing method, but digital printing is becoming the predominant technique as technology continues to improve. The most notable difference between these two printing methods is that where offset printing requires a metal printing plate, digital printing does not. Instead, the image that needs to be printed is created digitally. The result is a much faster process with less setup time and lower upfront costs. Since the image is digital and not created by a plate, digital printing can also enable you to recreate any image on demand for small and fast print runs.
How digital printing works depends on the technique. There are several popular forms of digital printing, with inkjet and xerography chief among them.
- Inkjet Printing: In inkjet printing, a series of print heads sprays tiny droplets of ink directly onto the paper. The printer receives the digital version of the image from a computer and recreates it, cutting both the printing plate and the rubber blanket out of the process. Inkjet printing is ideal for lower-volume print runs, and it is most popular for limited or print-on-demand runs of books, posters, signs, and more.
- Xerography: Previously called electrophotography, xerography uses electrical charges to attract toner to a metal cylinder called a drum. As in inkjet printing, the printer receives digital information about the image and recreates it and the ink is transferred directly to the print media. In xerography, instead of print heads propelling the ink directly onto the paper, the drum attracts the toner particles and presses them to the paper. Finally, a fuser is used to melt the toner into the paper to make sure that the ink has sufficiently permeated the media. The laser printer in your office is an example of xerographic printing. This method is popular for printing business documents and paperwork and limited runs of books, labels, and promotional materials.
In most cases, digital printing can't rival offset printing regarding quality. However, it is faster, more efficient, and less expensive in most cases, which is why offset printing is typically only used for high-volume print jobs.
Dot Matrix Printing
Dot matrix printing is another type of computer printing but one that has largely been rendered obsolete by inkjet printing. In dot matrix printing, a print head moves side to side on a piece of paper, slowly punching letters or images into the paper. This printing method uses a matrix of dots to create letters and then uses impact or pressure to print them onto the paper. Nowadays, dot matrix printers aren't often seen in homes because they are slow and noisy. They are also not the most practical choice for printing brochures, books, or promotional materials. However, they continue to have a place in modern culture: they are usually used to print receipts.
Flexography—or “flexo” printing—is a type of “relief” printing method. Using a rubber plate with protruding letters, shapes, or images, flexography is the process in which a rubber plate is inked and then used to transfer the relief image onto a printing media. Flexography can be used to print on virtually any type of media, including metal and plastic. In most cases, this type of printing is used for packaging materials, particularly food packaging.
In gravure printing, the image is engraved directly into the surface of a printing cylinder. Using a rotary printing press, the cylinder is then inked to transfer the image onto the printing media. Once upon a time, gravure printing was popular in newspaper printing, particularly for large photo features. Today, it is more likely to be found in the magazine publishing or packaging industries. Gravure may be a dying printing art, as offset printing tends to be more popular for publications and flexo printing is more common in packaging.
Instead of using a printing plate or a rubber relief block, screen printing uses a piece of mesh fabric to transfer an image onto the print media. To create the necessary shapes and images, screen printers use a blocking stencil to render certain parts of the mesh impermeable. The ink then permeates the other areas of the mesh screen and transfers the image to a printing substrate. Because the mesh screen is flexible, the substrate does not have to be a traditionally “flat” media such as paper or cardboard. As a result, the most common application for screen printing is printing images and designs on t-shirts.
An entirely different technology than the other printing techniques listed here, 3D printing is still evolving as we speak. Using an “additive” process, 3D printers create layers of plastic or other materials to manufacture 3D objects. From creating 3D models to help with project planning to engineering custom implants for medical patients, the potential applications for 3D printing are nearly limitless. In all likelihood, 3D printing isn't the most practical choice for your own applications, but the growth of this extremely versatile printing method could influence multiple industries in unexpected ways in the near future.
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I am surprised you did not mention heat transfer printing.
I used to work designing printed graphics for Black & Decker. Our most common method for high speed manufacturing was heat transfer tapes. A long film tape with million’s of logos on it would be fed into the production line (typically a plastic injection molding machine). A hot stamp would then press each graphic onto the surface 100’s of times a minute. The blank tape would come out the other side of the machine.
Great point, Cort!
This post was supposed to be a quick overview of the main printing types. We’ll be following up with a part two shortly, but I don’t think that contains heat transfer… yet 😉