What is printing bleed?
In simple terms the bleed is room for error. The bleed allows for tiny imperfections in the printing process and irregularities when trimming the print. The bleed is there to make sure the finished print is as clean as it can be.
Without bleed you run the risk of unwanted borders and white edges ending up in the final print.
The bleed can often be mistaken for a margin, however unlike a margin the bleed is an extension of the design. The bleed also represents an area of the design which will be discarded in the final process.
So let’s say I am making an advert for a print in photoshop, I often get a brief like this:
200mm x 150mm
5mm bleed means the design needs and additional 5mm of space in all directions.
This is what confuses some people because suddenly you start doing the maths in your head and wondering how big the canvas will need to be.
Shouldn’t I make my new document 210mm x 160mm?
You can, but I prefer another way.
This is how I do it:
Create a new document that is 200mm x 150mm like the brief explains.
I would go ahead and change the units under Edit, Preferences. This will make sure all the rulers show mm not pixels. It just makes it a bit easier.
Next add guides to the edges of document like so.
View, Guides, New Guide Layout.
Now I add the bleed by extending the canvas size.
Image, Canvas Size.
With relative ticked, I add 10mm in width and height.
Why 10mm? because I need 5mm in both directions. An easy mistake which I have made a few times.
Now I have my document set up correctly with guides showing me the area of the design that won’t be cropped away.
Sometimes this additional space can throw off your judgement slightly whilst designing so sometimes I add a mask.
This is very simple, all I do is fill a new layer with a colour I often sample the workspace colour.
Next using the guides I already set up I select the inner area and delete it. (Make sure you have snap enabled so that your selection snaps to the guides).
Now I have a bleed mask I can turn on and off.
Be careful when adding additional guides that you don’t tick the Clear all existing guides, this will remove the bleed guides we set up.
If this happens you can use your bleed mask layer to create new guides.
Just remember to hide or delete the layer when you send your file to the printer.