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News . Print Solutions

12 Jan 2019

Flexo printing (or flexographic printing) and offset printing are ostensibly similar processes, in that both methods employ wet ink and printing plates. Both are ideally suited to long runs of identical items, where the costs and time commitment of the set-up process can be divided between a greater number of printed items.

Flexo printing presses are renowned for their economies of scale, and also for the high speeds at which they can be run. These savings – in terms of both time and money – can then be passed onto clients whilst still maintaining viable margins. While historically this printing method was time-consuming in the set-up phase, more modern printing equipment has resulted in significant streamlining improvements.

Offset printing is similarly well-suited to longer print runs, and also enables PSPs to offer great value to clients wanting hundreds or thousands of identical items. This method also delivers excellent colour register and reproduction.

So with two printing methods both suited to volume jobs, how do you know which is right for your business? Now that we’ve reviewed the similarities between these two approaches, let’s see what differentiates them.

The key difference between flexo printing and offset printing lies in the way that the ink is applied to the chosen substrate. With offset printing presses, the ink is transferred from the printing plate to an intermediate carrier – typically a rubber blanket – before it reaches the paper. Flexographic printing, in contrast, does away with the “middleman” – the ink is applied directly to the substrate from the plate.

Further differences include the varieties of inks and plates involved, and the types of substrates that can be used. While both methods use so-called “process” inks (that is, the basic building blocks of colour, namely cyan, magenta, yellow and black), flexo printing does not rely on these inks for spot colours, but rather uses pre-mixed inks. The separation of colours results in much crisper reproduction, but the flexo process offers a wider range of compatible inks, including UV-curable inks which permit faster running speeds (and further cost-savings in terms of reduced time per job).

Plates represent another crucial difference between flexo printing and the offset process. The “flex” in flexographic comes (of course) from “flexible” – these printing presses use plates that can be wrapped around a printing cylinder. With the polymer on the non-print portions of the plate washed away, the ink is then transferred from the ink well onto the flexo plate, and then directly onto the substrate. As noted previously, a separate plate is required for each colour.

The aluminium plates used in offset printing equipment receive ink that is transferred (or “offset”) from rollers, before the complete image is transferred again to the rubber blanket, and thence to the substrate.

When it comes to compatible substrates, offset printing is ideal for materials such as paper, metal, cardboard, cellophane and vinyl, as long as the printing surface is flat and smooth. Offset is the optimum method for newspaper printing, for example. Additional processes such as die-cutting and laminating require passing the printed materials through a secondary, offline process.

Flexo – as the name again suggests – offers more options when it comes to substrate.  Flexography is ideal for packaging applications using materials such as cellophane, foil, cardboard, fabric, plastic, metal. Flexo printing can be used on almost any substrate with a flexible surface, while multiple built-in options in flexo printing equipment permit single-pass printing and processing.

When it comes to choosing which printing method is right for your company, you need to weigh up the superb colour reproduction achievable with offset printing against the versatility of flexography.

When combined with its productivity advantages, and the fact that flexo can be more easily integrated into a digital printing environment, it could well be the case that flexo printing is the process with the brighter future.

For more help or advice when it comes to choosing between flexo printing and offset printing, contact Kemtek to learn about our printing solutions.