This will vary by printer and they will usually give you instructions. Here’s what I’m doing at the moment for the UK’s RAP Spiderweb, a very helpful and friendly printer:
- Include 3mm bleed to all edges of each page, so an A4 page would measure 216mm x 303mm. You can choose the bleed when you create a new document (the “More options” button in Indesign CS4), or if you’ve already made a document, you can add bleed by going to File > Document Setup > More Options.
- All images must be 300dpi, pantone (spot colour), CMYK (full colour process) or greyscale (black and white). .tif is prefered. If they’re jpegs, make sure they’re on the maximum quality setting. For images made in Adope Illustrator or Photoshop, it is best to place the .ai and .psd files directly in the Indesign document rather than exporting them in a different format. Don’t use .eps images – it’s an old format that does wierd things in Indesign / pdfs.
- Preflight – Check everything is ok before you send it to the printer. “Preflight” is named for the preflight check pilots do on aircraft, same idea here. In Indesign CS4 you have a “live” preflight which checks for possible printing errors as you go – it’s in Window > Output. In older versions it’s under the File menu. Either way, you’ll only really want to use it near the end, because if you work like me, you’ll have blocks of text and images sitting on the art board waiting to be used, all of which will show up as errors.
- Saving as a pdf: PDF/X. When you go to File > Export Adobe pdf, the pull down menu of options at the top of the window is “Adobe PDF preset”. You have a few options, including three “PDF / X” settings. PDF/ X is an ISO standard, a refinement of the PDF format for printed files. For example, in PDF/X-1a all images need to be CMYK or spot colours, while PDF/X-3 accepts calibrated RGB and CIELAB colours. Most printers want PDF/X-1a:2001, but for Indesign CS 4 (not CS 2/3) you want PDF/X-4:2007 so the transparency works correctly. My printer also requires the following changes in the Export pdf window:
Compression > De-select ‘Crop Image Data to Frames’
Marks and Bleeds > Only select the following: Crop Marks; Page Information; 5mm offset; 3mm bleed
Output > Colour conversion: Select ‘No colour conversion’
Advanced > Transparency Flattener High Resolution
- Saving as a pdf: Embed / subset fonts. When you export your Indesign document as a pdf, you’ll see an option in the Advanced tab that says: Subset fonts when percent of characters used is less than: 100%. “Subset” means it only saves the font for those characters used in your document, rather than embedding the entire font. You’re best off subsetting the font, for two reasons. One is that some fonts have thousands of glyphs, so the file size will be be big. Another reason is that to edit the text the printer would have to have the font locally installed on their machine anyway (if it’s a licensed font), so embedding the entire font won’t help them. Leave the setting at the default “Subset fonts when percent of characters used is less than: to 100%”. If you do need to embed the font (as some printers require) set the percentage to “0%”.
RAP Spiderweb printers have more information on their pdf here.