How We Pre-flight Your Artwork (and How to Supply the Perfect Print PDF)

Quick answer: Every file we receive goes through a pre-flight check before it's proofed. Software checks the technical structure of your PDF against our own Adobe Acrobat preflight profiles, one for digital and litho print and one for wide format, and fixes the routine problems automatically. Then a person checks what software can't: bleed, trim, layout, overprint and anything that looks wrong. To make it as smooth as possible, supply a PDF/X-4 file with 3mm bleed, with all colours in CMYK using the Coated FOGRA39 colour profile. We'll happily accept PDF/X-1a as well.

"Pre-flight" sounds technical, and the jargon around it doesn't help: PDF/X, output intents, total area coverage. But the idea is simple. Like a pilot's checks before take-off, it's a routine that catches problems on the ground, where they're cheap to fix, rather than in the air, where they're not.

This guide opens up exactly how we do it. Designers will find the specifics useful. Everyone else will at least know what's happening to their file, and why we sometimes come back with a question before we print.

Part One: What We Ask You to Supply

The short version

Why CMYK?

Presses print with cyan, magenta, yellow and black ink, so CMYK is the language your file will end up in. Setting your colours up in CMYK from the start means what you see on screen is much closer to what comes off the press, and there are no surprises when bright screen colours are converted. It's the simple rule of thumb we recommend for every job. Our RGB vs CMYK guide explains the difference in plain English.

Why PDF/X-4 rather than PDF/X-1a?

Both are international standards for print-ready PDFs. Both require fonts to be embedded and a colour profile to be declared, and both rule out the things that cause trouble at print stage. The main difference is how they handle transparency.

• PDF/X-1a forces every bit of transparency, such as drop shadows, glows, soft edges and blend modes, to be "flattened" into solid pieces in your design software. It's predictable, but flattening is where the familiar problems creep in: fine white lines appearing through artwork, or text near a shadow turning into outlines or pixels.
• PDF/X-4 keeps the same safeguards but lets transparency stay live, so our presses render it natively and cleanly.

There's another good reason: an X-4 file can always be turned into an X-1a file, but an X-1a file can never be turned back. Once transparency has been flattened, that information is gone. Because one piece of artwork might end up on our digital presses, with a litho partner, or on our wide format printers, X-4 keeps every option open until we've chosen the best route for your job.

A note on RGB and wide format

There is one situation where RGB can be worth keeping. Our wide format printers can reproduce a wider range of colour than standard CMYK, so for vivid photographic posters, banners and display graphics, a colour-managed RGB image can hold on to a little more vibrancy. It's a specialist route rather than the rule, so if your job is colour-critical or photo-led, ask us first and we'll tell you whether supplying RGB is worth it and how to set the file up.

How to export a PDF/X-4

• Adobe InDesign: File → Export → Adobe PDF (Print). Choose the [PDF/X-4:2008] preset. Under Marks and Bleeds, tick Crop Marks and Use Document Bleed Settings (set your document bleed to 3mm). Under Output, check the output intent shows Coated FOGRA39.
• Adobe Illustrator: File → Save As → Adobe PDF, then choose the [PDF/X-4:2008] preset, with trim marks and 3mm bleed under Marks and Bleeds.
• Affinity Publisher or Designer: File → Export → PDF, choose the PDF/X-4 preset, and include bleed and crop marks.
• Canva: Canva doesn't export PDF/X, and that's fine. Download as PDF Print with crop marks and bleed (choose CMYK if your plan offers it), and our pre-flight will take care of the rest. Our common print mistakes guide has the exact Canva steps.

Part Two: What Our Pre-flight Checks

When your file arrives, it's run through one of our own Acrobat preflight profiles, depending on how it will be printed:

• Digital & Litho, for brochures, leaflets, flyers, business cards, stationery and anything printed on our Konica Minolta AccurioPress presses or by our litho partners.
• Wide Format, for posters, banners, display boards and graphics printed on our Epson and HP machines.

Each check has a level. Errors stop the file until they're resolved. Warnings are reviewed by a person and usually raised with you. Info items are noted, so we know what we're working with.

Part Three: What Our Pre-flight Fixes Automatically

Many problems don't need to come back to you at all. Our profiles fix these as standard, at no cost:

Colour (digital & litho)

If anything in your file isn't already CMYK, whether that's an RGB photo, a Lab colour or a spot colour, it's converted to CMYK using Coated FOGRA39, the standard European profile for coated paper, which is then embedded in the file as its output intent. A few details in how we do this make a real difference:

• Your CMYK colours are left alone. If you've built a colour in CMYK, we don't re-convert it. Your 100% black text stays 100% black, and a rich black built as C60 M40 Y40 K100 stays exactly that.
• Black objects are preserved, so black text doesn't get turned into a four-colour mix that could print soft.
• Black point compensation is used, which keeps detail in the shadows of photographs instead of letting dark areas fill in.
• Transparency is set to blend in CMYK, so drop shadows and blend modes behave predictably on press.

That conversion is a safety net, not a substitute for setting up in CMYK. Bright RGB colours, especially vivid greens, blues and oranges, can look noticeably duller once converted, which is why we'll point out any visible shift on your proof.

Spot colours are converted to CMYK as standard, because our digital presses print in CMYK. The exception is Spot UV and foil work, where the spot colour is what tells the finishing equipment where to apply the effect. Those jobs have their own separate check, so the spot colours are kept exactly as supplied.

Colour (wide format)

Our wide format profile does not convert colour to FOGRA39. Instead, colour is handled by our ONYX RIP software, which converts it directly for the specific printer and material your job is printed on. CMYK files print exactly as you'd expect, and where we've agreed an RGB file with you for a photographic job, ONYX can make the most of the printer's wider colour range.

Everything else (both profiles)

• Fonts embedded where they're missing and the licence allows it.
• Over-resolution images sampled down to 300ppi, using high-quality bicubic sampling, if they're above 450ppi.
• 16-bit images reduced to 8-bit, which is all a press can use.
• Hairlines thickened to a minimum of 0.14pt.
• Form fields flattened, so anything typed into an interactive PDF prints as it looks.
• Old halftone instructions removed, so our presses use their own screening.
• Lossless compression applied, keeping files lean without touching image quality.

Part Four: What a Person Still Checks

Software is brilliant at the technical structure of a file. It has no idea whether your design actually looks right. So after the automated check, one of our team looks at every file:

• Size, bleed and trim: is the file the finished size of the product, does every background run 3mm past the edge, and are there crop marks?
• Safe area: is any text or logo too close to the trim, a fold or, on wire bound work, the punched edge?
• Page order and count: for brochures, are the pages in reading order, starting with the cover, and is the page count a multiple of four?
• Overprint and separations: using Acrobat's Output Preview, we check for objects set to overprint that would vanish in print. This is exactly how a sponsor's name disappeared from every page of a 60-page brochure in the story we tell in our common print mistakes guide.
• Blacks: is text a clean 100% black, and are large black areas a proper rich black rather than a flat grey-looking black or a 400% registration black?
• Images: any image flagged as low resolution is checked by eye at full size. Some look fine; some don't.
• Anything that just looks wrong: a stray placeholder, a missing image, text running off a page. After decades in print, we notice these things.

What we can't check is your content: spelling, phone numbers, prices and dates. That's why the next step matters.

Part Five: Your Proof

Once your file has passed pre-flight, we send you a proof of exactly what will print. Our artwork review notes anything we've changed or noticed, such as the colour shift from converting RGB to CMYK, or an image that's on the borderline, and asks you to check the proof carefully before approving. You can see the whole process, including what's in our quotations, in our guide to what happens after you order.

Routine pre-flight fixes like the ones above are free. If a file needs more work, such as resizing artwork supplied at the wrong size or rebuilding a page, we'll tell you first. That's charged at £35 per hour in 15-minute blocks, so a typical quick fix is £8.75 + VAT.

For Designers: Matching Our Colour Setup

If you'd like your Adobe applications to behave the way ours do, our studio colour settings are based on Adobe's Europe Prepress 3 preset, with two changes:

• RGB working space: sRGB IEC61966-2.1
• CMYK working space: Coated FOGRA39, with all colour management policies set to Preserve Embedded Profiles

We use Prepress 3 rather than General Purpose 3 because it preserves CMYK numbers. In InDesign, that means placed CMYK images and colours aren't re-converted on export, so a 100% black stays 100% black and your rich black stays exactly as you built it. Set it up once in Photoshop (Edit → Color Settings), save it, then apply it to all your Adobe apps through Bridge.

Frequently Asked Questions

What is pre-flighting in printing?

Pre-flighting is a check of a print file before it's printed. Software checks the PDF's technical structure, such as fonts, colour, image resolution and file errors, and a person checks the layout, bleed and overall appearance. Print Studio Scotland pre-flights every file it receives, free of charge.

Should I send PDF/X-4 or PDF/X-1a?

PDF/X-4 is recommended. It keeps transparency live so it prints cleanly, and it can always be converted to PDF/X-1a if needed, but not the other way round. Print Studio Scotland also accepts PDF/X-1a.

Should my artwork be in CMYK or RGB?

CMYK, using the Coated FOGRA39 colour profile (also listed as ISO Coated v2), the standard European profile for coated paper. RGB can occasionally be useful for photographic wide format work, but ask us first.

What happens if my file has low-resolution images?

Images below 200ppi are flagged and checked by eye at full size. If they're likely to look soft or pixelated in print, we'll tell you before printing and ask for a higher-resolution version.

Do you fix problems in my file?

Routine fixes are made automatically and free of charge, including converting any RGB to CMYK, embedding fonts, sampling down over-sized images and thickening hairlines. Bigger fixes, such as resizing artwork, are quoted first and charged at £35 per hour in 15-minute blocks.

Do you keep spot colours?

Spot colours are converted to CMYK as standard for digital print. For Spot UV and foil work, spot colours are kept as supplied, as they tell the finishing equipment where to apply the effect.

Can I send artwork from Canva?

Yes. Download as PDF Print with crop marks and bleed. Canva doesn't export PDF/X, but our pre-flight checks and prepares the file for print.

Not Sure Your File Is Ready?

Send it over before you order and we'll run it through pre-flight and tell you honestly whether it's ready to print. Call 0141 237 1924, email hello@printstudioscotland.com or get in touch. You'll find artwork guides for every product we print in our Print Learning Centre.

Stuart Wilson, founder, Print Studio Scotland