The email lands mid-afternoon, usually from someone apologetic. There is a problem with your file. It has no bleed, or the colours are RGB, or would you please approve the attached proof before five o'clock. If you designed the thing in Canva or Word on your lunch break, none of those words help.
They all describe real problems, and every one of them is fixable in minutes once you know what the printer is looking at.
What bleed is for
Commercial printing does not print your leaflet one at a time on leaflet-sized paper. It prints many copies on a large sheet, then a guillotine cuts them apart. Guillotines are accurate to a millimetre or so, not to a hair. If your background colour stops exactly at the edge of the page, a cut that lands a fraction out leaves a white sliver down one side.
Bleed is the fix: you extend any edge-touching colour or image about 3mm past the page boundary, so a slightly wayward cut still lands on ink. The matching rule is the quiet zone, keeping text at least 3mm inside the edge so nothing important gets trimmed. When a printer says your file has no bleed, they are asking you to export it again with those extra millimetres, which most design tools do with one checkbox.
Why the red on screen is not the red on paper
Screens make colour with light, mixing red, green and blue. Presses make colour with ink, layering cyan, magenta, yellow and black. The two systems overlap but do not match, and the brightest screen colours, vivid oranges, electric blues, lime greens, sit outside what ink can reach. A file supplied in RGB gets converted to CMYK somewhere along the line, and the press picks the nearest printable colour, which can look flat next to what you saw on screen.
You cannot beat this, but you can control it. Convert to CMYK yourself before you export, so the dulling happens on your screen where you can adjust for it, rather than on the press where you cannot.
The proof is not a formality
A proof is the printer showing you exactly what will be produced, and asking you to own it. Once you approve, mistakes in the file become your mistakes, including the typo in the phone number that four people have already read past. Check the proof as if you had never seen the artwork: read every number by dialling it, check the postcode, look at the trim edges, and view it at full size rather than squinting at a thumbnail.
If the proof looks wrong, say so. Printers would far rather run a second proof than reprint a job, and a firm that gets impatient about corrections at proof stage is telling you something useful about how the rest of the job will go.
Sending a file that prints first time
The safe recipe has not changed in years: a PDF, with 3mm bleed, in CMYK, with fonts embedded, at 300dpi for any photographs. Ask the printer for their file specification before you export; most have a one-page guide and will happily send it.
Better still, ask before you book. There are 2,868 printing companies listed on this site, and how a firm answers a file question is a fair preview of how it handles a job. You can browse printers near you and put the question to a couple of them, or describe your job and request quotes. Either way, export one test PDF with bleed today and look at the edges. It is a five-minute check that saves a reprint.
