What is the difference between offset printing and digital printing?

Years ago, digital printing was thought of as the evil stepchild to the moreimages.005 sophisticated and aesthetically pleasing method of offset (or litho) printing.  With the advances in digital press technology, from the way the image is printed to the paper, to digital presses now having 26″ or even 32″ sheet length capacities, it’s more difficult to distinguish between the two processes.  I’ve had success printing a cover for a short run perfect bound book on our 28″ Komori litho press, and all the text printed on our digital Nexpress.  However, there are differences, advantages and disadvantages to both processes, so let’s take a look at those.  I wrote a post a year ago about this topic, but I wanted to revisit it, giving the reader the differences, advantages and disadvantages to each method.

LITHO (OR OFFSET) PRINTING

fourth_photo_bigLithographic, or offset printing, is the process of ink transferring through a series of rollers to the printing plate, which is then transferred in reverse to a sheet of rubber called a blanket, and then transferred finally to the sheet of paper.  Regardless if you’re printing in 4-color (Cyan, Magenta, Yellow or blacK – CMYK), or a PMS (Pantone Matching System) color, the process is the same.  What are the advantages to offset printing?  Let’s list them out:

  • More consistent color throughout the run, and from run to run.
  • Solids print cleaner and without streaking, especially if you double-hit them.
  • PMS colors can be used, important if you work with specific branded colors.
  • Better suited for longer run jobs.
  • Can image on a sheet up to 28×40″ (some presses are even larger).
  • Can run a broader range of paper thicknesses than digital, from 50# offset to 24 pt board.

But there are disadvantages as well:

  • Make ready, which means the loading the paper into the press, mounting the plates to the press, running paper through the press to get to color, is costly, and is amortized over the run length.
  • Ink dry time impacts how soon the job can be backed up or worked on in bindery.
  • Cost for short run is high due to the fact that file prep, proofs and make ready is not spread out over the run length as efficiently as they would be on a long run.

So, what kind of jobs are suitable to offset printing?

  • Catalogs and books
  • Dependent upon the item (say an 8.5 x 11″ sheet or 11 x 17″ sheet), and the final quantity is 5,000-10,000 or more, litho printing is more cost effective
  • Long run packaging

DIGITAL PRINTING

Most digital print presses run a dry toner that is transferred to an imaging cylinder, then1_a2301cdb3b1e0ce1cd4856038482c80c to a rubberized blanket, and then finally to the substrate that is being printed on.  This is done with an electrostatic charge, and then the image is “fused” to the paper under extreme head and with a fine layer of oil. Digital printing has advanced so much – even in the last few years – that it is difficult to distinguish between digitally printed items and litho printed items.  Now, let’s list the advantages to digital printing:

  • There is no make ready.  The file is sent to the press, imposed for the sheet, and the operator runs out a few sheets for color and content review, and then the job can be run.  You CAN make color adjustments on the digital press, but it’s best to make sure that all color is adjusted in the file beforehand.
  • You can run a job of 25 pieces or 250 pieces, and the cost is low since there is no make ready.  With online orders (run digitally) there’s no prep – it’s all automated.
  • Personalization, where each piece has unique content, can be done since it’s generated through a file, not from a printing plate.
  • Jobs print 2 sides in a single run, and are dry as soon as they leave the press, so you can do any post-press finishing immediately.

Disadvantages:

  • Solids, or heavy colors, called “flat fields” can be susceptible to streaking, and can look bad, even if the press is given a full maintenance before the job is printed.
  • Solids along a fold or crease can crack, and if it’s a saddle-stitched item that has a solid on the spine, can crack easily.
  • The per click charge (what each sheet costs running through the press) does not decrease as drastically over the run length, so longer runs can actually be more expensive than litho jobs.
  • Press sheets for digital presses tend to be 14 x 20″ maximum.  Some presses have larger sheet capacities, like 26″, 29″ or even 32″, but not all print services providers have those presses installed.
  • Digital presses can “drift” during the course of a long run, requiring calibration, and even with that, there is no guarantee that color will remain consistent in a run.  Also, trying to “match” a previous run is extremely difficult as well.

The types of jobs best suited for digital printing:

  • Short run pieces where quality and consistency are not the main focus
  • Personalized pieces for use in marketing campaigns
  • Direct mail if the run is short
  • Small booklets and catalogs
  • Short run packaging for trade shows or FDA approval

CONCLUSIONS

old-time-printing-pressAs a print sales consultant, my goal is not to “sell” one method over the other, but to advise as to which method would benefit the client based on expectations and the scope of the work.  For example, if a client wants only 200 brochures, then digital is the best option. However, if they want 200 perfect bound books, I will look at both options. Conversely, if they are looking at printing 20,000 flyers, I won’t even talk to them about digital.  If they are concerned about corporate color accuracy, I will lean more towards litho, since I can actually secure the PMS color match.  It really does come down to what is the best method to achieve the optimal client results.  It’s also an opportunity for me to help educate my client, so they themselves can make the best choice as well.

Connect with John on Google+Twitter and LinkedIn.

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About John Prothero

John Prothero is a print professional with over 30 years experience in the print industry. Starting out as a driver delivering jobs, he worked in bindery, proofing, plating, traditional prepress (camera and stripping), scheduling, job planning, job management, account management and digital job production. His skills also run in the area of blog authorship, social media management, and lead generation and qualification of prospective clients. John is also a contributor to Rhode Island Creative Magazine, a digital publication that highlights the creative spirit of the state of Rhode Island. You can read their online issues at www.ricreativemag.com
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2 Responses to What is the difference between offset printing and digital printing?

  1. Rachelle says:

    Offset and digital are both useful printing methods. Each has particular benefits depending on your project’s requirements. Your article is very accurate and comprehensive that I didn’t need to read more. Though, I prefer digital printing since we are in a modern time. Worth sharing!

  2. Gary says:

    I don’t have any printing projects at this time, but if I did you would be my guy!

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