Flexographic Printing in action
Flexographic Printer in action – Photo by Dale Simonson

Promotional plastic bags and kraft paper bags have a few things in common, they are cheap and can be supplied in large runs, they are perfect for retail situations and they can both look great with the right branding. And that’s where flexographic printing comes into it. Flexo is the way large runs of kraft paper or plastic bags get branded!

But not everyone knows what flexographic printing is or how it works. Here at Kan we like to help our customers understand how to get the best from their promotional products. So we thought it would be good to put together a guide to flexo printing. How it works, what it’s good at, and what you need to be careful of when you choose your artwork.

How does Flexographic Printing Work?

The actual idea behind flexographic printing is pretty simple. An image is transferred to a flexible rubber sheet (hence the name!) The sheet is etched so that raised areas are left where you want ink to appear and then the sheet is fitted to a roller. An ink roller transfers ink to the raised sections which are then rolled onto the bag material, leaving an image behind.

What is Flexographic Printing Good For?

Flexo is a simple, fast printing technique. The prints might not be the most detailed (although technology keeps on improving the results!) but you will be hard pressed to beat the sheer speed that can be achieved.

The flexible plates are wrapped around a roller, so that they can be printed onto a continuous roll of material. That roll is fed from the printing station, straight into an automatic cutting and folding machine, which pumps out finished bags as fast as it can.

Flexographic plates are sturdy too, which means they can be re-used again and again. Need another 10,000 bags? You won’t need to buy another set of plates, just use the old ones for a new run!

What Should You be Careful of With Flexographic Printing?

Flexo plates cannot directly print shading. Halftones must be used to simulate shading, but the rubber sheets are not suitable for very small details, so the halftone pattern will be easily visible on the finished product. For some designs, this can be used as a feature, as long as you know it’s what you will be getting!

Shading in Flexographic printing must be simulated using halftone patterns.
Shading in Flexographic prints must be simulated using halftone patterns.

Multiple colours can be used, but it is a good idea to try and keep registration to a minimum. The high speed, roll to roll nature of Flexographic printing means that some tolerance in colour alignment will be allowed. Trapping, where colours are deliberately overlapped, can be used to mitigate the effects in many cases. Our production teams will be able to advise you further when they see your artwork.

This tolerance in alignment also means that full colour prints should be normally avoided. Misalignment in CMYK printing can cause moiré patterns and other undesirable effects. If you do need a full colour image, high resolution flexo plates could be the solution. But unfortunately, these are only available on a limited range of bags, and come at a premium price too!

Is Flexographic print right for your brand?

The best way to know for sure is to let the Kan branding experts take a look! Get in touch with us and we can advise you on the perfect print techniques for your next campaign.

Take a look at our kraft paper bag range, including our Apsen kraft paper bag, or our plastic bag range to see more examples of flexographic printing in action.