As a printer every day we are dealing with multiple files supplied by clients or perhaps designers working on their behalf. We find that most files supplied do not have 3mm bleed added. Bleed of 3mm should be added by the person suppying the file so it is print ready so that all the printer has to do is open the PDF file impose and make plates if it is an offset litho printing job or impose and print if it is a digital print job. Bleed of 3mm should be added when colour prints to the edge of the sheet so in effect the colour is extended over and above the finished size. This means that when the print job is cut on the guillotine no slithers of white are left showing. It also allows the print finisher more latitude for fine adjustments at the folding or booklet making stage for example. The best thing to do is speak to your printer about the job you have in mind as at Kopykat we will often try and flag up issues regarding bleed at an early stage. On many occasions a PDF file will be sent to us to produce an urgent job and if it is supplied without bleed we then need to go back to the client asking them or their designer to add bleed and resupply the file. This can slow down the production process at a critical stage and lose valuable production time. Many clients will use freelancers which is fine but if they are unavailable more time can be lost. Designers who deal with traditional print on a regular basis will automatically add bleed and crop marks when supplying to the printer however if the designer is more of a web designer used to working digitally on screen bleed does not come into the equation and they may not be aware that this is required. For more advice about bleed https://www.kopykat.co.uk/artwork-advice/ or email email@example.com and we will send you a PDF that shows an example of how it should be done.