Our regulars often tell us, "I've printed with you plenty of times — you don't need to check my files again." We politely say no. It isn't only that we worry the customer slipped up; more often we're guarding against problems that creep in while the file is being prepared. With print artwork, even a designer or ad professional who knows the craft inside out will fumble a file eventually — everyone gets caught out one day. Preflighting is something we insist on, and it's part of our responsibility to you. Below are a few of the problems we turn up again and again while checking artwork.
CMYK vs RGB
Almost everyone printing for the first time runs into this one. If you never have, either the print shop or your designer quietly fixed it for you. RGB is emitted light — a screen actively generates it. CMYK depends on reflected light; with no light, you can't see CMYK at all. The colours used in printing are CMYK. If you never studied physics, all you really need to know is that the CMYK gamut is roughly one-third of the RGB gamut.
So when we use software to convert a design file or image from RGB to CMYK, the colours always come out less vivid. There's no way around it — some RGB colours simply don't exist in CMYK. During the check we have to make sure the artwork is in CMYK; if it isn't, we convert it.
Even after the conversion, the CMYK colours your screen shows will still look more vivid than the physical print. And because the substrate differs, the printed colour will shift too — so customers with strict colour requirements should always order a physical proof before committing to the full run.
Further reading: How to convert RGB to CMYK — and what to watch out for
No bleed set on the artwork
Bleed is one of the things we check most closely. Printing always involves some cutting tolerance, and that variance can spoil the finished look. Without a bleed, trimming can leave a white edge wherever the cut drifts. Because the cutting machine runs non-stop, trimming jobs of every size, some drift is inevitable. A proper bleed protects your artwork so that even after the cut shifts, the content still fills the edge with no white slivers.
Because paper products tend to be small, even a 2mm drift shows. So when we check a file, we pay extra attention to whether a bleed has been set.
Further reading: Setting bleed on a print file is easy — simple tutorials for several apps
Missing fonts and images
Designers working in Illustrator (AI) or Photoshop (PS) often hit missing-font and missing-image problems, and both do serious damage to the final print. No print house owns every font in the world, and even a font with the same name may not be the same version. That's why we ask designers to outline their type on export — converting editable text into non-editable vectors. That way the fonts can't be altered by anything downstream.
On export, designers also frequently forget to embed their images, so when we open the file the picture is missing. Since we can't tell whether that missing image was meant to be part of the design, this is exactly when checking the file becomes essential. Print it as-is and the result may not match the design.
Further reading: "Create Outlines" is a must before you export a print file
Image resolution problems
Low image resolution ruins the finished print. If an image already looks blurry on screen, it will certainly print blurry. So before printing we have to confirm the image resolution is high enough for the job. Often an image that looks perfectly sharp on screen still doesn't meet print requirements.
Images for print generally need to be 300 PPI or higher, depending on the finished size and the paper. The smaller the product, the shorter the viewing distance, and the higher the image quality it demands. Large-format ads have gentler requirements, because they're viewed from a distance where fine-detail problems are hard to spot.
Further reading: PPI vs DPI — what's the difference, and why you must understand it before designing for print
Finishing file problems
The finishing file is another part of the check we can't skip. Finishing is separate from printing — most of it happens after the print is done — so when we build the print file we have to isolate the finishing areas on their own, ready for the next stage in the process. That's why we confirm with the customer more than once that the finishing positions and content are correct.
Checking artwork protects more than us — it protects you and the print
The checking process may be laborious, but it's strongly necessary. If we catch a problem or an error while reviewing the file, we can still put it right before printing — once a job is on the press, there's no turning back. The last thing we want is for a customer to miss the result they had in mind because of a file problem.
Not sure your artwork is print-ready? Send it over and we'll check it before it goes to press, or WhatsApp us at +852 3001 5678 (English is fine). We deliver across Hong Kong and Macau.