Set Up Bleed
If setting up a new document
- Select File/New
- Change Units to Millimetres
- Change Bleed to 3mm
- Change Colour Mode to CMYK Colour
- Set Raster Effects to High (300ppi)
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If you already have a document,
- Click off the artboard
- Select Document Setup
- Set Bleed to 3mm, and click OK
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- A red bleed line will appear around the Artboard
- Extend background colour to the bleed line
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- Extend the background colour to the bleed line
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- Save with the appropriate PDF Preset
(See how to set up a PDF Preset)