Each printer tends to have a desired bleed, the standard for smaller printed items (business cards, flyers etc.) tends to be 3mm per edge, but on things like banners, it can go up to 10mm because of the size, so 10mm isn't that big percentage-wise. if they want 0mm bleed, they are probably copy-shop style printers, as I don't know how it would be trimmed without getting a white edge.
I wrote a how-to to help explain bleed to customers: https://fasprinting.co.uk/design-for-print-bleed-slug-and-crop-marks-explained/ Any feedback is appreciated on ways to improve it. Do you think I need a video showing examples?
if they want 0mm bleed, they are probably copy-shop style printers, as I don't know how it would be trimmed without getting a white edge.
That's actually very good and the way I would have explained it.
I remember doing something similar to explain the difference between vectors and rasters as it was a nightmare when clients would send in tiny .jpeg images of their logos grabbed from their web-sites.
Not necessarily - I've printed on sheets up to 10 meters and cutting it on a specially designed table with a cutter purpose-built - the table length was the length of the factory with a custom cutter the length of the factory (the factory wasn't that long)
Firstly - you need to line up the cut marks - which is impossible to do by eye - so when the output of the large format items is printed, there is generally an option to place a Box around it which is about 1mm thick.
This provides the guide from cutter mark to cutter mark - you then trim inside this line so it doesn't end up on the printed material.
So bleed is unnecessary in some cases - but no harm to include it - but mostly it would be ignored by some systems.
The system I worked for years was to remove the crop and bleed edges, leaving just the artwork, and applying the black box around the artwork on output. Then trimming inside this line.
With large format - unless it is cut out with a laser-guided cutter (or a laser cutter) you won't get it straight from edge to edge.