What is the difference between litho and digital printing?
The main differences are that litho printing uses wet ink and printing plates whereas digital printing uses toners on a press similar to a very large office printer. Digital printing tends to be more suitable for shorter runs whereas litho printing works best for longer runs.
How does offset lithography (litho) printing work?
During offset litho, the inked image is transferred from a printing plate to a rubber blanket and then the image is transferred once again again to the paper or card by the standard four-colour process. This means that the artwork is separated onto four different printing plates and each plate prints a specific single colour – cyan, magenta, yellow and black, also known as CMYK. These colours then combine together to create a full-colour print.
Depending on the job it may sometimes be necessary to use additional printing plates to print spot colours which are special inks such as fluorescent, metallic or a specific Pantone ink that matches a corporate colour. If a specific Pantone colour is required to a high level of accuracy then litho printing is the best option.
Can you tell me more about litho printing?
A large proportion of the cost is ‘making ready’ the job. This means the cost and time involved in making the plates and running the press until all the plate images are in register and the job can be run. Once this is done however, the cost per copy on longer print runs such as 2,000 upwards on flat work and 1,000 upward on brochures will be cheaper than digital printing. It should be noted that litho printing isn’t really suitable for short-run printing as it is not as cost-effective as digital printing.
Printing is not limited to four colour process (CMYK) only as special or spot colour inks can be included to enhance the finished result. This is very noticeable when printing orange, as a spot colour it will give you a nice bright effect, whereas CMYK will give you a muddy brown hue.
Litho printing gives much better results for large areas of solid single colour as the colour comes out smoother with no banding. Traditionally in pre-press when film was used to make plates, a 40 or 50% cyan tint was added under the solid black, known as a ‘shiner’ to make the colour appear deeper and more intense.
The introduction of computer to plate making (CTP) has resulted in much quicker plate making and coupled with modern computer controlled presses can speed up the process of colour control and getting plates into accurate register.
The turnaround time is usually longer with litho, normally 5 working days. This is to allow time for the ink to completely dry before finishing. If it’s a longer run job, it may have to be scheduled to run on larger presses.
Let’s have a look at some of the plus points and negatives with digital printing
Digital printing is very cost effective for small print runs because there is less initial setup involved. As no printing plates are needed, there is less wastage as ‘make-readies’ are not required.
Quick turnaround is possible as the job is produced ready to go with no additional drying time required.
Digitally printed jobs can be personalised as they are printed with variable data – such as numbering, names, addresses or contact details making each print unique to the recipient, i.e. a direct mail campaign could have the name of the recipient incorporated into the design to make it more personal to them.
The finished product doesn’t have a coating applied over the print such as a sealer, therefore it can be prone to marking and scuffing.
Digital printing using toners can mean that there is some cracking when a job is creased or folded which can be more noticeable on thicker stock such as card. It can also result in lamination bubbling or not adhering properly across the crease.
Digital printing won’t reproduce tints, gradients and large solid areas of colour as well as litho printing.
You may also want to consider other factors too.
What weight of material can I have?
As a rule of thumb most digital presses will run paper weights between 80gsm and 300gsm, whereas litho presses have a much wider range, anything from 60gsm up to 500gsm.
What type of material can I have?
Digital presses are limited in the types of material onto which they can print. Some textured materials don’t print too well and gloss papers can also end up looking a bit flat if there is a large image coverage. Litho presses have a much wider choice of materials available which are generally cheaper if you need a specialist stock.
What is the run length?
Digital presses are more suitable for the shorter runs, generally from a single print up to around 500 – 1000 copies, whereas litho presses can run anything from 1000 upwards.
What is the lead time?
If time is critical then digital printing produces a job quicker than litho printing as there is no job make-ready or plate making required. You could always have a small run digitally printed initially with a longer run litho printed as time allows.
What is the quality like?
Litho printing has always been regarded as producing the best quality, and whilst that is true for many job specifications, digital print quality is now so good that in most cases it is hard to tell the difference.
I hope you have found this article useful.