A designer's guide to printing a poster

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Taking digital designs into the real world can be fraught with gotchas and gremlins. We’re so used to the world being digital that some of us have forgotten how to prep our work for print. This poster printing guide is here to help.

If you’re thinking of doing a run of poster designs for a campaign, party or gig (or simply to adorn your own walls with) here’s a guide to how to print your work. Follow our tips and you'll soon be poster printing with confidence – and you'll no longer have to worry about that guy in the printing shop laughing at you...

If you don't want to go to a professional, or if you want to try and few practice runs with your design, you'll need the right printer. Take a look at our roundup of the best home printers for some guidance.

01. Design in CMYK

Work in CMYK rather than RGB

If you're producing your own designs with the intention of taking these to a poster printing shop, then make sure you're working in the CMYK colour space rather than RGB. In Photoshop you can easily switch to this mode via 'Image > Mode > CMYK color'. This colour mode will give you a more accurate representation of how your colours will print.

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02. ... or convert to CMYK

If you’ve been working in RGB and have converted your work to CMYK, just before you send the file for printing you may notice the greens and blues in your image have become lifeless and dull. You can use Photoshop’s Gamut warning tool ('File > View > Gamut warning') to highlight the colours that will have trouble converting from RGB to CMYK.

• How to master colour theory

The RGB colour space has a greater array of colours than CMYK. Remember: all the computer-specific colours you pick in Photoshop for your poster then have to be printed with a selection of real-world inks. Those that can't be replicated will become 'out of gamut', and be printed with what is possible with the available inks.

03. Use vectors if possible

Designer Franz Jeitz advises: "When it comes to printing, especially large-format printing, vectors are your friend. Try to design as much as possible in a vector-based program such as Adobe Illustrator. Not only will it reduce your file size, but it will ensure that you get the crispest print result."

04. Work at 300DPI

Skinn's super-sized posters for a Belgian arts centre

Print files are BIG. One of the most common delays in poster printing jobs is work being sent back by the printer because the resolution is too low. Files destined for print should be set to 300 DPI (dots per inch). Simply put, the more dots that make up the image, the higher the resolution. More printed dots in an inch means a higher-quality reproduction.

If your resolution is too low, you're going to end up with a blurred and pixelated poster. In Photoshop you set the dots per inch when you create a new document ('File > New'). 300DPI is the standard resolution you want for a good quality print document.

05. Select your paper

Popular poster printing sizes are A2 (594mm x 420mm), A3 (420mm x 297mm) and A4 (297mm x 210mm). Paper choice and weight can be discussed with your printer, but 170gsm Silk or Gloss Art FSC or 150gsm are good choices. GSM stands for grams per square meter and determines how heavy the paper stock is.

06. Supply files as PDF

Supply your print files in the PDF format (print resolution at 300 DPI) or tiffs with no compression at the same DPI. It is possible to send JPGs if they’re high-res enough. So if you just want to print a poster of your pet pooch from a photo on your smartphone you can do this by sending a JPG, but be warned: the edges of the photo will be cut off and the colour will shift.

07. Consider litho printing

You'll need to decide between digital and litho printing

You have two choices for poster printing: digital or litho. (Well, okay you have three: you can always print at home. But chances are you don’t have a printer big enough.) A wide variety of mass-produced print items (books, posters, newspapers and so on) are produced using litho printing. Put simply, a litho print involves the printer making a set of 'plates' that are used to press the image to the paper.

Creating these plates comes at a cost and doesn’t offer the immediacy of digital poster printing. The initial outlay can be expensive, but if you’re doing a large print run and want to output up to A1, it’s the process that offers a higher quality print and finish than digital printing.

The choice between digital and litho printing will mostly be dependent on the money you have for the print job and how soon you need it doing. Digital printing with inkjet or laser printers is the cheaper and quicker of the two and good for smaller print runs. If budget is an issue and you’re not being too exacting over the quality, go with digital printing. This is also fine if you're not going above A3.

08. Choose the right poster printing shop

Different printers have different levels of expertise, so it's worth doing your homework and getting personal recommendations. Also make sure you tailor the printer to the job at hand.

In the UK, for example, Metroprint is well known for high quality and specialist work as well as being one of the few places around to use laser light source printers and genuine black and white photographic prints. For high quality, crystal clear prints on heavy stock, quality Kodak paper these are the people to visit.

However, you might just want to print lots of stuff digitally without a special finish or on the highest grade paper. So don't write off high street poster printing at places such as Prontaprint and Snappy Snaps. There's a reason they're everywhere: they offer a decent, affordable service and will print your photo posters direct from a memory stick, mobile phone, Instagram or Facebook. They can also help you enhance your work with a range of photo art effects.

Next page: bleed rules, vectors, and the final checks you should be making...

09. Check your spelling!

Even if there are only a few words – as on this poster series by Fatih Hardal – double and triple check them

Luke Woodhouse advises that you to "spellcheck, spellcheck, spellcheck. Then get your mum to spellcheck it and anyone else who will read it for you. There's nothing more soul-destroying than a typo, and they're easy to miss if you're too close to your masterpiece." And that goes for the big words as well as the small ones – its not uncommon to caught up in checking the small print, only to miss a glaring error in the headline. 

10. Set the correct bleed

What is bleed? It's simply a little margin (usually 3 or 5mm) around the edge of your poster design that, depending on how the printer cuts the paper down, may or may not be shown in the finished result. It's essentially your room for error and ensures there isn't a random white line on the edges of your printed poster.

Programs such as InDesign and QuarkXPress make it easy by showing you guides, so you can see where the bleed starts and finishes. Always ask the printer you're using (or check your own printer settings) to determine how much bleed is required for your poster printing.

11. Consider the trim

The trim is the edge of the final printed output. To prevent text or logos being chopped off the final output, they should be placed with some breathing space around them. Design elements should be no closer to the trim edge than 3-5mm, depending on the size of the poster. 

12. Run a pre-print check

Always run a pre-print check. This will bring up any issues, such as RGB files being used or fonts used that aren’t embedded. In InDesign this is known as a 'pre-flight'. The programme can package up all your print files and links ('File > Package') into one folder, which will spare you any missing font nightmares.

13. Get your blacks right

Ben Powell advises you avoid RGB black as it will look grey in print

Ben Powell suggests: "When printing posters using black, there are so many different types of black you can use (RGB, Photoshop, neutral rich, registration, flat, designer, and so on).

"My tip would be to avoid RGB black as this is primarily used for the web/digital and will look washed-out and grey in print. Which black you should use will depend entirely on your printing process and what paper stock you're using, especially if you're printing solid blacks.

"When I designed a recent infographic piece, I spent days printing various different blacks on different stocks of paper to get the most accurate black whilst making sure the colours didn't bleed into each other; a really lengthy but worthwhile process. Always leave plenty of time to test your blacks – it can completely ruin a fantastic poster design if you don't."

Related articles:

• How to get more from your print projects: 5 top tips
• Create special print finishes in InDesign
• How to prepare a file for print

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