Getting it printed
Friday 25 September 2015
You’ve done all the hard work and commissioned the perfect design. Now you just need to work out the best way to get it printed and you’re done. It’s surprising how many people think about design and print as two separate processes, but they are, in fact, almost inextricably linked.
The two main commercial printing methods in use are offset lithography and digital. But what is the difference, and how should you choose which to use? I caught up with Matt Taylor, Managing Director of Colour Options in York to get his expert technical viewpoint on this perennial question.
SC: What kind of litho and digital presses do you run?
MT: We run an HP Indigo Digital Press, and a range of different sized litho presses which we use depending on press suitability for the job – using the larger presses for bigger numbers of pages for brochure work and the smaller format press for stationery.
SC: What are the main technical differences between the processes of litho printing and digital printing?
MT: Litho is a well-established printing method and the process is standardised across the industry. The same cannot be said of digital printing, where presses vary massively using a wide variety of technologies depending upon the manufacturer. At Colour Options we run an HP Indigo press, which is capable of very high quality printing.
Both litho and digital printing (on the HP Indigo) use an offset process where the image is transferred to the paper via a rubber blanket.
The difference between the two processes is that litho printing uses aluminium plates, whereas the HP Indigo uses a combination of photo imaging plates and electrophography. This means that whilst litho presses will reproduce the same image over and over, digital presses can vary the image on each sheet.
The ink used is completely different for each process. The HP Indigo uses a liquid electro ink. Some lower end digital machines use powder-based toners which are applied in much thicker layers to the sheet, which produces cruder results.
SC: Is it possible to tell the difference between something that has been litho printed and something that has been digitally printed? Are there any telltale signs?
MT: The digital we print is very close to litho in quality, so generally it is quite difficult to tell the difference.
When printing large areas of solid colour on a digital press there can be some banding that appears. However, depending up on the press used, litho printing can also have issues with roller stripes and ghosting. Ghosting is where feint copies of the printed image appear on other parts of the page. It can be caused by a number of technical reasons.
SC: Digital printing used to be considered to be inferior in quality to litho printing. Is this still the case?
MT: Not any more but the quality of digital printing can vary a lot depending on the printing equipment. Digital printing is also now able to handle Pantone, metallic, and white inks, so the range of design options is wider than it ever used to be.
SC: Is there anything that digital printing can do, that litho printing cannot?
MT: Digital presses have the unique ability to vary the image on each sheet using variable data. This can be used to make every sheet different, which has a wide variety of uses, such as personalised print.
SC: Does digital printing have any advantages or disadvantages over litho printing?
MT: HP Indigo digital printing produces extremely good colour onto uncoated stocks whereas litho can be quite dull due to the ink being absorbed into the paper. Digital printing also dries straight away so it can be finished quicker. This is particularly relevant when printing on uncoated stocks. Digital presses can now cope with a wide variety of different sorts of paper, but some of them will require priming with an invisible sapphire coating prior to printing in order to make them receptive to the inks.
SC: What are the main factors to consider when deciding whether to print digitally or litho?
MT: Choose your print provider wisely if you are looking to match quality between short runs printed on a digital press, and longer runs which are printed on a litho press. You also need to bear in mind that litho turnaround times are generally longer because of plate-making, make-ready, and additional ink drying time needed, so you’ll need to allow more time for your job to be produced.
Digital printing has a more constant ‘cost per copy’ throughout a job since it does not use so many materials and time setting up the job on press. Cost per copy on a litho press starts high because of the set up costs and materials involved in producing plates, but this gradually drops until the cost is little more than that of the paper and ink being used. The result of this is that digital print is often more cost-effective on shorter runs, and litho is often better when print runs are longer. The exact crossover point will depend upon the equipment that is being used by your printer, so it’s a good idea to ask for quotes based on both methods if you are unsure.
Some jobs could be printed in either way, but most of the time there are aspects of the specification of a job which mean that one process is better suited to your job than another. So, the best time to start thinking about which printing method you are going to use is before you start designing!
Colour Options is an independent printing company in York which began operating in 1995. They offer a first class service in both litho and digital printing, along with a wide range of finishing options.